Pathogenesis of early cardiac myocyte damage after severe crush injury

AIM:To study the changes of plasma atrial natriuretic peptide(ANP), endothelin-1 (ET-1) and serum cardiac troponin I(cTnI) levels and the effects of ANP and ET-1 on myocardium in crush injury rats.METHODS:Crush injury was produced in SD rats,the serum levels of cardiac enzyme and cardiac troponin I,plasma levels of ANP and ET-1 were studied by automated biochemical analyzer,automated chemiluminescence assay and radioimmunoassay. RESULTS:The plasma ET-1 level was much lower,the levels of plasma ANP and serum cardiac enzyme and cTnI were much higher after crush injury than those of the control group(P＜0.05).CONCLUSION:ANP and ET-1 may play an important role in cardiomyocyte injury in the early stage of crush injury.     

The protective effects of angiotensin Ⅱ receptor blocker irbesartan on kidney function in diabetic rats

AIM: To investigate the effects and mechanisms of irbesartan, one of the angiotensin Ⅱreceptor blockers, on kidney function in diabetic rats. METHODS: Forty adult male Wistar rats were randomly divided into four groups: control group, diabetes group, irbesartan group and captopril group. At the end of 12 weeks, the rats were sacrificed. Urine volume, body weight, kidney weight/body weight, plasma, glucose, glycosylated hemoglobin (HbA₁c), urinary β₂-microglobulin (β₂-MG) excretion, urinary albumin excretion rate (UAR), creatinine clearance (Ccr) were measured. Nitric oxide (NO) and endothelin-1 (ET-1) levels in plasma, urinary and renal tissues were determined. RESULTS: Urine volume, kidney weight/body weight, plasma glucose, HbA1C, UAR, Ccr, urinary β₂-MG excretion, NO and ET-1 levels of urinary, blood and renal tissue in diabetic rats were significantly higher than those of normal controls ( P<0.01). UAR, Ccr, urinary β₂-MG excretion, ET-1 and NO levels of urinary and renal tissue in rats of irbesartan and captopril groups were significantly lower than those of DM rats ( P<0.01). There were positive relationships among the levels of plasma, urinary, renal tissue ET-1, NO and UAR, Ccr and urinary β₂-MG excretion. CONCLUSION: Irbesartan could prevent from the injury of renal function in STZ-induced diabetic rats. And it maybe one of the most importan mechanisms that irbesartan could reduce the NO and ET-1 levels in STZ-induced diabetic rats.     

The protective effect of preconditioning on rabbit liver during ischemia and reperfusion and its potential mechanism

AIM:To investigate the protective effect of preconditioning on rabbit liver during total ischemia and reperfusion and its mechanism. METHODS: Using hepatic ischemia and reperfusion injury (HIRI) model in rabbits, animals were randomly divided into three groups: control group (A), non-preconditioning group(B) and preconditioning group(C), different effects of preconditioning on several parameters including alanine aminotransferase (ALT) activity and levels of nitric oxide (NO) and malondialdehyde (MDA) in plasma or liver tissue as well as hepatocellular morphological changes were measured and observed during HIRI. RESULTS:In C group NO levels of plasma and liver tissue were higher than those in B group (P＜0.05);While MDA levels and ALT value in plasma were lower than those in B group (P＜0.05 and P＜0.01); and there were not significant differences between C and A group (P＞0.05); abnormal morphological chages of liver cells in A group were ameliorated remarkably too during HIRI. CONCLUSION:Preconditioning can attenuate HIRI by improving NO level and reducing oxygen free radicals level.     

Protection of the limb ischemic preconditioning on the injury of gut is concerned with NO/ET-1 system in rats

AIM: To study the relationship between disturbance of nitric oxide/endothelin-1 (NO/ET-1) and the injury of gut following limb ischemia-reperfusion (I/R) in rats as well as the regulation of NO/ET-1 system by limb I/R preconditioning (IPC). METHODS: A limb ischemia-reperfusion injury model in rats was established. The animals were randomly divided into three groups: control group, IR group and IPC group. The contents of diamide oxidase(DAO), nitric oxide (NO), endothelin-1 (ET-1) and ratio of nitric oxide/endothelin-1 (NO/ET-1) in the plasma and the gut were measured. The leavels of myeloperoxidase, ratio of DNA chain (%), total nitric oxide synthase (tNOS), inducible nitric oxide synthase (iNOS) and constitutive nitric oxide synthase (cNOS) in the gut were determined. The expression of iNOS and endothelial NOS (eNOS) were detected by the immunohistochemical method. RESULTS: It was found that the levels of NO, ET-1 in the plasma and the gut tissue all increased after reperfusion, while the values of NO/ ET-1 decreased. The values of DAO in the plasma and MPO in the gut increased, while the contents of DAO and the ratio of DNA chain (%) in the gut decreased. The expression of iNOS elevated, cNOS (mainly eNOS) reduced and total NOS increased. The protection of the limb IPC attenuated the disturbance of NO/ET-1. CONCLUSION: The intestinal injury following limb I/R is related to the disturbance of NO/ET-1. The protection of the limb IPC might be conducted by its regulating NO/ET-1 system. The endothelial NOS increases and non-endothelial NOS decreases in this situation.     

Impact of hydrogen sulfide donor on endothelin-1 and connective tissue growth factor expression in rats with pulmonary hypertension induced by high pulmonary blood flow

AIM: To explore the possible impact of hydrogen sulfide (H2S) donor-sodium hydrosulfide (NaHS) on endothelin-1 (ET-1) and connective tissue growth factor (CTGF) expressions in rats with pulmonary hypertension induced by high pulmonary blood flow. METHODS: Thirty-two male SD rats were randomly divided into 4 groups: shunt group, shunt+NaHS group, sham group and sham+NaHS group. Rats in shunt group and shunt+NaHS group were subjected to an abdominal aorta-inferior vena cava shunt to create an animal model of high pulmonary flow. After 11 weeks of experiment, rat systolic pulmonary artery pressure (SPAP), lung tissue H2S, plasma ET-1 concentration and lung tissue ET-1mRNA expression, as well as pulmonary artery CTGF protein expression were detected.RESULTS: After 11 weeks of experiment, SPAP, lung tissue ET-1mRNA, plasma ET-1 as well as pulmonary artery CTGF expressions were increased markedly, respectively, whereas H2S in lung tissue decreased significantly in rats of shunt group as compared with that in sham group (all P<0.05). After administration of NaHS for 11 weeks, H2S in lung tissue increased significantly, whereas SPAP, plasma ET-1 and lung tissue ET-1 mRNA expression as well as pulmonary artery CTGF protein expression decreased significantly, respectively, in rats of shunt+NaHS group as compared with that in shunt group (all P<0.05).CONCLUSION: NaHS might be involved in the development of pulmonary hypertension induced by high pulmonary blood flow by down-regulating vasoactive peptides ET-1 and CTGF expressions in lung tissues of rats.     

Relationship between endothelial dysfunction and renin-angiotensin-aldosterone system under the condition of fatigue stress and effect of herbs to dredge collaterals

AIM: To investigate the mechanisms and relationship among endothelial dysfunction, renin-angiotensin-aldosterone system (RAAS) and family of interleukins under the condition of excessive fatigue, by using the rats with fatigue stress. METHODS: Healthy male Wistar rats were randomly divided into control group, homocysteine (HCY) group, fatigue stress group, renshen group, shuangshen group and tongxinluo group. Radioimmunoassay was carried out to detect plasma renin activity (PRA), angiotensin II (AngⅡ), aldosterone (ALD), endothelin (ET), thromboxane-2 (TXA2), prostaglandin I2 (PGI2) in plasma and interleukin-1β, 2, 6, 10 (IL -1β, IL -2, IL -6) in sera. ELISA was used to detect NE and IL -10. The content of nitric oxide (NO) in sera was also detected. The bioinformatical analysis was used to determine the relationship between RAAS and endothelial dysfunction. RESULTS: Compared with control group, the levels of ET-1 and TXA2 in fatigue stress group were significantly increased (P<0.01, P<0.05), but the content of PGI2 and NO was significantly decreased (P<0.01, P<0.01). Compared with control group, the renin activity in plasma of animals in fatigue stress group was significantly decreased (P<0.01), the AngⅡ, IL -1β, IL -6 level was significantly increased compared with the control group (P<0.01, P<0.01), and was significantly increased compared with the HCY group (P<0.05, P<0.01, P<0.01). The NE level showed the tendency of decrease in different degree. After the intervention of three kinds of herbs to dredge collaterals, the ET-1, AngⅡ, IL -1β, IL-6 level in plasma was decreased in different degree (P<0.05, P<0.01, P<0.01), and at the same time, the contents of NO and NE level were significantly increased (P<0.05). The ALD level in tongxinluo groups was apparently higher than that in control group and the fatigue stress group (P<0.05). The bioinformatics analysis showed that Ang II and ET, IL-1; PGI2 and ALD; NO and ALD composed of three subsystems and interrelated according to the principle of optimality of complex system, and gradual change regulation was also observed in fatigue stress group. However, in control group, HCY group and tongxinluo group, the same interrelation among subsystems was not existed. CONCLUSION: In a state of long-term excessive fatigue, vascular endothelial dysfunction may be induced, and is related with renin-angiotensin-aldosterone system imbalance and serious turbulence of the autonomic dysfunction. Herbs to dredge collaterals could improve it significantly. The results suggest that bearing excessive fatigue and pressure in long-term may be the potential risk factors to induce vascular endothelial dysfunction and further result in cardio-cerebro vascular diseases, Tongluo therapy may be one of the useful ways to prevent such diseases.     

Plasma levels of endothelin-1, nitric oxide,malondialdehyde and superoxide dismutase in rats exposed to infrasound

AIM: To observe the changes of NO, ET-1, SOD and MDA levels in plasma of rats exposed to infrasound. METHODS: Using infrasound (frequency: 8 Hz; sound pressure level:130 dB), the rats were exposed for 1 d， 7 d， 14 d， 21 d and 28 d, 2 h daily, then the levels of NO, ET-1, SOD and MDA were measured after exposure. RESULTS: The changes of NO levels in plasma significantly declined at 7 d and 14 d （P<0.01）, then 1, 21 and 28 d normally （P>0.05）. The changes of ET-1 levels in all groups in plasma were significantly increased （P<0.01）, mostly at 7 d, least at 14 d. The changes of SOD activity in all groups in plasma were significantly declined （P<0.01）. The changes of MDA levels in all groups in plasma were significantly increased （P<0.01）. CONCLUSIONS: Infrasouns induces changes of NO, ET-1, SOD and MDA in rat plasma, and it depends on infrasound exposure time.     

Pathophysiologic changes of local ischemic coronary artery and cardiac muscle after ligating canine LAD

AIM: To evaluate the reliability of making a research model of coronary artery stenosis and local myocardial infarction reproduced in dog by ligating canine LAD. METHODS: We disparted 30 aged healthy cross-breed dogs ［(18.5±6.7) kg］ into three groups. The near part of the LAD through left minimal thoracic incision was ligated to interdict 25% (group A), 50% (group B), 75% (group C) of the flux, respectively. The changes of plasma endothelium-derived factors NO, ET-1, sP-selectin and CTnT were measured before ligation and at different time points after ligation. The expression of P-selectin gene in cardiac muscle was detected by Western blotting. The segments of distal parts of the ligated LAD were cut and pathological changes of the patches of topical cardiac muscle were observed by electronic microscope. RESULTS: After ligation, NO/ET-1, P-selectin and CTnT had significant changes in group B (P<0.05) and group C (P<0.01). The expression of P-selectin of cardiac muscle was highly up-regulated after ligating in B (50%) and C (75%) group, In C group animals, a typical far more intense expression pattern was found. Under electronic microscope, the endothelium and other structures of the LAD wall and ultrastructure of myocardial cells had obvious changes in later two groups, especially in group C. There were a typical stenosis of LAD and myocardial infarction. CONCLUSIONS: Ligating the LAD 75% severely damages the endothelial cell and cardiac muscle cells of local ischemic vessel and cardiac muscle, thus forms the typical local stenosis of coronary artery and myocardial infarction, such method is a safe and reasonable way for making a disease model for studying CABG in surgery.     

The regulation of nitric-oxide synthase/nitric-oxide system by endogenous carbon monoxide in rats with pulmonary hypertension

AIM:To study the role and the mechanism of heme oxygenas/endogenous carbon monoxide on nitric oxide synthase/nitric oxide system in rats with pulmonary hypertension induced by hypoxic hypercapnia.METHODS:Sprague-Dawley rats were randomly divided into three groups: control group (A group), hypoxic hypercapnic group (B group), hypoxic hypercapnia+hemin group (C group). Blood CO concentration (COHb%), NO concentration, HO-1 activity, iNOS, cNOS in blood serum and lung homogenate were measured, respectively. RESULTS:① mPAP and RV/(LV+S) of B group were significantly higher than those of A and C group(P＜0.01).② Blood CO concentration, activity of HO-1in blood serum and lung homogenate in rats of B group were significantly higher than those of A group, but were significantly lower than those of C group (P＜0.01). ③ NO concentration in blood serum and lung homogenate in rats of B group were significantly lower than those of A group, those of C group were significantly higher than those of B group (P＜0.01).④The activity of iNOS in blood serum and lung homogenate in rats of B group were significantly higher than those of A group, but were significantly lower than those of C group (P＜0.01). Activity of cNOS in blood serum and lung homogenate of B group were significantly lower than those of A group (P＜0.01), and there was no significant difference between cNOS in B and C group.CONCLUSION:Endogenous carbon monoxide upregulated iNOS/NO system in rats with chronic pulmonary hypertension induced by hypoxic hypercapnia.     

Effect of puerarin on pulmonary arterioles wall collagen metabolism of chronic hypoxia hypercapnia rats

AIM:To investigate the effect of puerarin on pulmonary vessel collagen metabolism in pulmonary hypertension rats induced by chronic hypoxia and hypercapnia.METHODS:Collagen Ⅰ, Ⅲ and their mRNA were observed in pulmonary arterioles by the technique of immunohistochemistry and in situ hybridization.RESULTS:① Light microscopy showed media thickness of pulmonary arterioles was much higher in HH(hypoxic-hypercapnia) group than that of NC(normal control) group, and, vessel cavity turned more straiter in HH group than that of NC group.However, the damage of pulmonary arterioles in HP(hypoxic-pueratin) group was much slighter than that of HH group. ② The levels of plasma ET-1 and lung homogenates Hyr were much higher in HH group than those of NC group(P＜0.01), and lower in HP group than HH groups(P＜0.01).Plasma NO content in group HH was lower than that of group NC(P＜0.01), it was higher in group HP than that of group HH(P＜0.01).③Expression of collagen Ⅰ and collagen Ⅰ mRNA in pulmonary arterioles were significantly higher in HH groups than those of NC group (P＜0.01), and they were lower in HP group than those of HH group (P＜0.01).Expression of collagen Ⅲ and collagen Ⅲ mRNA showed no difference among three groups(P＞0.05).CONCLUSION:Puerarin inhibited the deposition of collagen and improved pulmonary vessel remodeling.     

The dynamic changes of plasma nitric oxide and endothelin-1 in prehepatic portal hypertension rats

AIM:To observe the dynamic changes of plasma levels of nitric oxide(NO) and endothelin (ET-1) in portal veins of the rats during prehepatic portal hypertension, and investigate the role of them in hyperdynamic circulation.METHODS:The models of prehepatic portal hypertension were established in Sprague-Dawley rats by means of partial portal vein ligation (PVL). The plasma levels of nitrite/nitrate (NO₂^-/NO₃^-) and ET-1 in the portal veins were detected by the method of nitric reductase and radioimmunoassay, respectively. In this study, rats were divided into normal, sham operation (SO) and PVL group. SO and PVL rats were divided into several subgroups according to different time after operations. Meanwhile, the changes of several hemodynamic indexes in these rats were also measured.RESULTS:The levels of NO₂^-/NO₃^- were significantly increased and ET-1 were significantly decreased in rats at different time after PVL compared with normal control, whereas the hemodynamic indexes changed accordingly.CONCLUSION:The portal hypertensive rats are in hyperdynamic circulatory state (HCS). NO and ET-1 may play an important role in the induction and maintenance of HCS.     

Relationship between levels of plasma endothelin-1/serum nitric oxide and hearing impairment in type 2 diabetes

AIM: To evaluate the relationship between endothelin-1 (ET-1)/nitric oxide (NO) and hearing impairment in type 2 diabetes mellitus (DM).METHODS: Eighty-eight type 2 diabetic patients with no signs of microangiopathy (retinopathy and nephropathy) or peripheral neuropathy, and 53 healthy subjects in the same period were enrolled in this study. Auditory function was evaluated using pure tone audiometry. Totally,type 2 DM group (n=88) and normal control group (NC, n=53) were divided into subgroups based on the presence and absence of hearing impairment. The concentration of plasma ET-1 was detected by radioimmunoassay. The concentration of serum NO was measured by the method of nitric acid reductase.RESULTS: Significantly increased plasma ET-1 and decreased serum NO were observed in diabetic patients with hearing impairment compared with those in diabetic patients without hearing impairment. The results of multivariate logistic regression analysis showed that hearing impairment in type 2 DM group was significantly associated with elevated level of HbA1c (OR＝4.525, P<0.05), LDL-C (OR=2.381,P<0.05) and plasma ET-1 (OR＝6.207,P<0.01). Besides, elevated serum level of NO (OR＝0.862, P<0.05) was associated with lower risk of hearing impairment in diabetics.CONCLUSION: Hearing impairment may happen earlier than other complications in diabetic patients. In addition to hyperglycemia and hyperlipemia, high level of ET-1 and low levels of NO might contribute to hearing impairment in diabetic patients.     

Effects of atorvastatin on nitric oxide,endothelin-1 and myocardial function in a rabbit model of acute myocardial infarction and reperfusion

AIM: To evaluate the effects of atorvastatin on nitric oxide(NO), endothelin-1(ET-1)and myocardial no-reflow in a rabbit model of acute myocardial infarction and reperfusion(AMI/R). METHODS: Twenty-four rabbits were randomized into 3 groups: 8 in AMI/R group, 8 in atorvastatin-treated group(5 mg·kg-1·d-1)and 8 in sham-operated group. Animals in the former two groups were subjected to 60 min of coronary occlusion followed by 120 min of reperfusion. Data on haemodynamics were collected. NO in blood sample, and in normal, and in infarcted reflow and no-reflow myocardium were evaluated respectively by nitrate reductase method. The levels of ET-1 in blood sample, and in normal, infarcted reflow and no-reflow myocardium were determined by radioimmunoassay. RESULTS: (1)Compared to the baselines, the heart rate(HR), systolic blood pressure(SBP), diastolic blood pressure(DBP), left ventricular systolic pressure(LVSP), maximal rate of increase and decline in left ventricular pressure(±dp/dtmax)and cardiac output(CO)in AMI/R and atorvastatin-treated groups were significantly declined, whereas left ventricular end-diastolic pressure(LVEDP)was increased after 60 min of coronary occlusion and 120 min of reperfusion(P<0.05 or P<0.01). However, in atorvastatin-treated group, LVSP, LVEDP, ±dp/dtmax and CO at the time point of 120 min of reperfusion recovered more significantly than those at the time point of 60 min of coronary occlusion(P<0.01), which was more significant than those in AMI/R group(P<0.05 or P<0.01). Compared to AMI/R group, the SBP and DBP were significantly heigher in atorvastatin-treated group(P<0.01).(2)In atorvastatin-treated group, the levels of ET-1 in blood sample were significantly lower than those in AMI/R group(P<0.01), and the levels of NO were significantly higher(P<0.01). Moreover, the levels of NO or ET-1 in infarcted reflow myocardium were significantly lower than that in AMI/R group(P<0.05 or P<0.01).(3)Atorvastatin could ameliorate myocardial function. CONCLUSION: Atorvastatin is effective in increasing NO and reducing ET-1 in blood plasma and local myocardium, and in protection of endothelial cells. Atorvastatin also has a beneficial effect on improving left ventricular function during acute myocardial infarction and reperfusion in rabbits.     

The relationship between nitric oxide and gastric mucosal injury induced by reserpine in rats

AIM: To study the relationship between nitric oxide (NO) and gastric mucosal injury induced by reserpine in rats. METHODS: Sixteen healthy male Wistar rats were randomly divided into control group and experimental group (n=8). NO contents and malondialdehyde(MDA) contents in plasma, gastric mucosa of the rats were respectively determined with Cadmium-reduct plus Greiss and TBA; nitric oxide synthase in gastric walls of the rats were observed using NADPH-diaphorase histochemistry and quantitatively measured with image analyzer. RESULTS: The NO contents in both plasma and gastric mucosa of experimental group were significantly lower than that in control group (P＜0.01),but their MDA contents were both higher than that in control group(P＜0.05,P＜0.01);the densities and A values of nitric oxide synthase (NOS)-positive nerve-cells and nerve fibers in gastric walls of experimental group were all obviously lower than that in control group (P＜0.05,P＜0.01). CONCLUSION: The mechanism of the reserpine-induced gastric mucosal injury in rats might be related to NO insufficiency arisen from the inhibition of NOS activity in NANC nerves in gastric wall,which might weaken the protection to gastric mucosa.     

Ischemic postconditioning ameliorates pia mater microcirculation in rats subjected to cerebral ischemia reperfusion

AIM:To investigate the ameliorative effect of ischemic postconditioning (I-postC) on pia mater microcirculation in rats subjected to cerebral ischemia reperfusion (I/R) and its mechanisms.METHODS:Thirty-two male Wistar rats were randomly divided into sham, I/R, I-postC, and ischemic preconditioning (IPC) groups.The global cerebral I/R injury was induced by shunting carotid artery in rats.Pia mater microcirculation and cerebral microcirculatory perfusion were measured after reperfusion.The content of soluble intercellular adhesion molecule-1 (sICAM-1) in plasma was detected using enzyme linked-immunosorbent assay (ELISA).Myeloperoxidase (MPO), malondialdehyde (MDA), and superoxide dismutase (SOD) in cerebral tissue were detected.The expressions of vascular endothelial cell cadherin (VE-cadherin) and NF-κB p65 in cerebral tissue were assayed by Western blotting.RESULTS:(1) The disturbance of the blood flow in microvessel induced by I/R was improved significantly by I-postC.In addition, I-postC alleviated significantly the decrease in diameters of microvesseles, cerebral microcirculatory perfusion and cerebral VE-cadherin content induced by I/R (P＜0.05).(2) sICAM-1 in plasma, MPO and MDA in cerebral tissue decreased, but SOD activity in cerebral tissue increased in I-postC group, compared with those in I/R group (P＜0.05 or P＜0.01).The over-expression of NF-κB p65 induced by I/R was relieved by I-postC (P＜0.05).CONCLUSION:I-postC ameliorates pia mater microcirculation in rats subjected to cerebral I/R through suppressing the activation of polymorphonuclear neutrophils mediated by ICAM-1.     

Effect of ligustrazine on pulmonary arterial pressure and pulmonary arterial wall collagen of chronic hypoxic hypercapnic rats

AIM:To study the effect of ligustrazine on pulmonary hypertensive rats induced by hypoxic hypercapnia. METHODS:Thirty rats were randomly divided into three groups:control group(A),hypoxic hypercapnic group(B), hypoxic hypercapnia+ligustrazine(lig.) group(C). RESULTS: (1) Mean pulmonary arterial pressure(mPAP)of group B was significantly higher than that of group A and mPAP of group C was significantly lower than that of group B(P＜0.01),differences of mean carotid pressure(mCAP) were not significant among three groups (P＞0.05); (2)Electron microscopy and immunohistochemistry showed ligustrazine could inhibit the diposition of collagenous fiber(collagen typeⅠ)in pulmonary arterioles induced by hypoxic hypercapnia; (3) Plasma endothelin level of group C was significantly lower than that of group B (P＜0.01), serum (NO ₂^-/NO₃^-) of group C was significantly higher than that of group B (P＜0.01). CONCLUSION:Ligustrazine can inhibit pulmonary hypertension and the diposition of collagen type Ⅰ in pulmonary arterial wall induced by hypoxic hypercapnia.     

Changes in endogenous nitric oxide and effects of inhaled nitric oxide on pulmonary artery hypertension in chronically hypoxic rats

AIM: To investigate the role of nitric oxide (NO)in the development of chronically hypoxic pulmonary artery hypertension (PAH) and the hemodynamic effects of inhaled NO on pulmonary circulation. METHODS: 67 male adult SD rats were randomly divided into 7 groups: (1) control (n=9);(2) chronically intermitent hypoxia (CIH, 6 h/d, 7 d/w) 1 week(n=7); (3) CIH 2 weeks (n=11); (4) CIH 3 weeks (n=11); (5) CIH 1 week+L-NAME (NO synthase inhibitor, 30 mg/kg, by gavage, n=10); (6)CIH 3 weeks+L-Arg (NO precursor, 10 mg/kg, by gavage, n=9); (7) CIH 3 weeks+inhaled NO (0.0004% for 20 min, n=10) to determine the mean pulmonary artery pressure (MPAP), weigh the right ventricle (R) and ventricular segment plus left ventricle (S+L), and calculate R/(S+L) (g/g) and R/Wt (Wt: body weight, g/kg). RESULTS: 1.MPAP increased compared with control when CIH 1 week, reaching the highest when CIH 2 weeks; R/(S+L) and R/Wt also increased notably when CIH 1 week (P＜0.01); 2. The level of plasma NO₂^-/NO₃^- elevated significantly when CIH 2 weeks, but fell when CIH 3 weeks; the content of plasma ET-1(endothelin-1) also increased significantly. The level of plasma ET-1 correlated with R/(S+L) and R/Wt, r=0.43 and 0.46, respectively, both P＜0.01; 3. The level of plasma NO₂^-/NO₃^- droped 33.2 % (P＜0.01) after treatment with L-NAME, with R/(S+L) increasing 15.2 % (P＜0.05); 4. L-Arg decreased the MPAP 17.8 %(P＜0.01). CONCLUSION: The endogenous NO release increases at early stage (1-2 weeks) of chronic hypoxia, but falls at the prolonged stage; the elevated level of plasma ET-1 possibly plays an important role in remodeling of chronically hypoxic pulmonary vessels and ventricle; inhaled NO significantly decreases the chronically hypoxic PAH.     

Effect of tissue kallikrein gene treatment on blood pressure in type 2 diabetic rats and its mechanism

AIM:To study the effect of tissue kallikrein gene (HK) treatment on blood pressure in type 2 diabetic rats and its mechanism. METHODS:Male Wistar rats were injected with low dose streptozotocin and fed with diets enriched in fat and sugar to form type 2 diabetic model. Recombinant adeno-associated viral vectors (rAAV)-mediated HK gene (HK group) or LacZ gene (LacZ group) was introduced to the diabetic rats. The systolic blood pressure was measured every 2 weeks. The acetylcholine (Ach)-dependent vasodilation response, the synthesis of nitric oxide (NO), the expression of endothelin-1 (ET-1) and endothelin-A receptor (ETA-R) in the aorta were detected. RESULTS:(1) Systolic blood pressure was significantly higher in diabetic rats than that in normal control rats. In HK group, systolic blood pressure was significantly reduced within 2 weeks after injection with rAAV·HK, reached near normal levels at 4 weeks and kept until the experiments ended (16 weeks). (2) In LacZ group, Ach-dependent vasodilation response of isolated aorta was markedly decreased than that in HK group (P<0.01). (3) The concentration of NO in the aorta of HK group were significantly higher than those in LacZ group. The expression of ET-1 and ETA-R mRNA were significantly decreased in HK group compared with those in LacZ group (P<0.01). CONCLUSION:rAAV-mediated HK gene delivery efficiently lowed blood pressure and attenuated the endothelial function partly through increasing the concentration of NO and inhibiting the expression of ET-1 and ETA-R of aorta in type 2 diabetic rats.     

Endothelin-1 and eNOS expression in pulmonary aterioles of patients with congenital heart diseases with pulmonary hypertension

AIM: To clarify the role of eNOS and ET-1 in development of pulmonary hypertension (PH) associated with congenital heart diseases. METHODS: 40 patients were randomly divided into three groups: severe or moderate PH group (group A, 12 cases), slight PH group (group B, 14 cases) and normal group (group C, 14 cases). ET-1 and eNOS were examined by using the technique of immunohistochemistry. RESULTS: ① Plasma ET-1 concentration was significantly higher in group A and B than that in group C (P<0.01). Serum NO concentration in group A and B was significantly lower than that in group C (P<0.01). ② The proliferation of medial smooth muscle cells and collagenous fibers of pulmonary arteriole in patients with PH were observed by electron microscopy. ③ ET-1 in pulmonary arteriole was significantly higher in group A and group B than that in group C (P<0.01). eNOS in pulmonary arteriole was significantly lower in group A and group B than that in group C (P<0.01). CONCLUSION: ET-1 and eNOS may play an important role in the pathogenesis of PH.