The effect of anti-digoxin antiserum on endoxin and membrane ATPase activity in hypoxic myocardium

AIM: To evaluate the antagonistic effect of anti-digoxin antiserum on hypoxic myocardium and its mechanism. METHODS: It was observed that different concentration of anti-digoxin antiserum effect on endoxin and cell membrane ATPase activity in hypoxic myocardium model.RESULTS: The endoxin level was much higher,cell membrane ATPase activity was much lower in hypoxic myocardium than those of normal; anti-digoxin antiserum can resume membrane ATPase activity. CONCLUSION: Rise of endoxin was basic in molecular biology of myocardial damage during myocardial hypoxia. Anti-digoxin antiserum decreased myocardial damage and has protective effect on hypoxic myocardium by antagonistic effect of endoxin.     

Clinical studies of L-Arg effect on essential hypertension

AIM and METHODS:To investigate the effect of L-arginine -nitric oxide pathway on patients with essential hypertension via hemodynamics and neuroendocrinology. 24 essential hypertension patients were randomly divided into two groups, group I was given L-Arg, and groups Ⅱ was given normal saline as control. Blood pressure, heart rate, heart funtion, nitric oxide, angiotensinⅡ, endothelin, thromboxane A₂ and prostacyline were measure in all patients. RESULTS: In group Ⅰ arterial pressure decreased, heart rate increased, cardial output, systolic volume and eject fraction increased, total peripheral resistance decreased. NO and PGI₂ levels were inceased. But at 80 min , with NO concentration decreased, SBP,DBP were increased, TPR, FT and AngⅡ were also increased. While HR, CO, SV and EF were decreased. However TXA₂ and PGI₂ showed not much change. CONCLUSION: Exogenous L-arginine produced a vasodilatory effect by increasing NO production ,caused the change of other hemodynamic function . It also indirectly changed plasma ET, AngⅡlevels by negative feed-back and suppressed the accumulation of platelet.     

Effects of nitric oxide inhalation on nitric oxide synthase and endothelin-1 in patients with hypoxic pulmonary hypertension

AIM: To investigate the effects of nitric oxide (NO) inhalation on nitric oxide synthase (NOS) and endothelin-1 (ET-l) of patients with hypoxic pulmonary hypertension. METHODS: Examined 13 pulmonic blood samples to determine the concentration of NOS in leukocyte and ET-1 in plasma before NO inhalation, 30 minutes after inhalation, 2 and 12 hours after stopping of inhalation respectiviy. RESULTS: The values taken before inhalation was NOS (0.70 ± 0.21 )mol/min·mg^-1, ET-1 (78.89 ± 46.59) Pmol/L; 30 minutes after inhalation (0.74±0.14)mol/min·mg^-1, ET-1 (88.27 ± 45.41 )pmol/L; 2 hours after stopping of inhalation NOS (0.64 ± 0.22)mol/min·mg-1, ET-1 (80.76±42.66)pmol/L; and 12 hours after stopping of inhalation NOS (0. 63± 0. 17)mol/min.mg-1, ET-1(61.07±29.44)pmol/L. NO significant difference was found in the values of NOS and ET- 1 before and after inhalation, P＞ 0.05. CONCLUSION: The effects of NO inhalation on NOS and ET-l in patients with hypoxic pulmonary hypertension are not significant according to the above investigation.     

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.     

Inducible nitric oxide synthase and arterial pressure regulation

AIM and METHODS:To clarify the role of inducible nitric oxide synthase (iNOS) in the regulation of blood pressure,in the present study, we examined the effect of aminoguanidine (AG), a selective inhibitor of iNOS on the hemodinamical response of Dahl salt-sensitive (DS) and Dahl salt-resistant (DR) rats to low (0.3%) or high (8%) sodium chloride (NaCl) infusion by chronical in vivo hemodynamic experiment, and the effect of NaCl or NaCl plus AG infusion on urinary nitrate (NO₃)/nitrite (NO₂), the end product of nitric oxide (NO), excretion by Greiss Reaction. Furthermore, NOS activity assay was also carried out to probe the effect of NaCl and AG on calcium-dependent or independent NOS activity in renal tissue. RESULTS:1. High or low NaCl-infused DR rats and low NaCl-infused DS rats have no hemodinamical response to AG, however, the hypertensive effect of high NaCl (8%) infusion on DS rats were greatly amplified by co-infusion of AG. 2. Administration of high NaCl significantly elevated the iNOS activity of renal tissue, and greatly increased urinary NO₃/NO₂ excretion. CONCLUSION:Inducible NOS is an important modulator of arterial pressure, especially in case of higher blood pressure.     

Effect of taurine on L-arginine/NO pathway in erythrocytes of rats of hypertension with insulin resistance induced by fructose

AIM and METHODS:The present study observed the change of L-arginine(L-Arg)/Nitric oxide(NO)pathway in ergthrocytes in hypertension with insulin resistance rat induced by fructose and the effect of taurine on L-Arg/NO pathway.RESULTS:Drinking 4%fructose, while inducing blood pressure, glucose and plasma insulin contents increase, obviously decreased the maximal velocity of L-Arg transport about 31%and 37%(P<0.01), more than that of control group in total and Y⁺ carrier, the NO synthase(NOS)activity, nitrite(NO₂^-)content and cyclic guanylate monophosphate(cGMP)level more than that of control group, but obviously enhanced Michaelis Constant(Km)about 35%and 30%(P<0.01)more than that of control group in total and Y⁺ carrier transport.The taurine treatment significantly counteracted the above changes.CONCLUSION:There exists a functional disturbance in L-Arg/NO system in the erythrocyte of hypertension rats with insulin resistance, but taurine can obviously enhanced the maximal velocity of L-Arg transport and NOS activity.Thus, it appears that taurinemay have vital value in the treatment of hypertension with insulin resistance.     

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.     

Association of endothelial nitric oxide synthase gene rs7830 and rs3918188 polymorphisms with essential hypertension in Kazakh of Xinjiang region

AIM: To investigate the correlation between endothelial nitric oxide synthase (eNOS) rs7830 and rs3918188 locus polymorphisms and essential hypertension (EH) in the Kazakh of Xinjiang region. METHODS: Epidemiological case-control study was conducted. DNA was extracted by classic phenol-chloroform method, PCR amplification and purification. The rs7830 and rs3918188 of eNOS gene in 363 EH patients (EH group) and 370 normotensive controls (NT group) in the Kazakh of Xinjiang region were genotyped by the technique of SNaPshot single nucleotide polymorphism genotyping. The plasma levels of fasting blood glucose, uric acid, cholesterol and triglyceride were measured by biochemical methods. Determination of body mass index and waist-hip ratio was also conducted. RESULTS: Age (P<0.01), body mass index (P<0.01), triglyceride (P<0.01), low-density lipoprotein (P<0.05) and apolipoprotein A1/B (P<0.05) were the independent factors for EH in the Kazakh of Xinjiang region. No difference of eNOS gene rs7830 and rs3918188 loci in the genotype frequency and the allele frequency distribution between EH patients and normotensive controls in the Kazakh of Xinjiang region was observed (P>0.05). The frequency distribution of CA, CC, AC and AA haplotypes from eNOS gene rs7830 and rs3918188 loci between EH group and NT group also had no difference in the Kazakh of Xinjiang region (P>0.05). CONCLUSION: Age, body mass index and triglyceride are the independent risk factors, while low-density lipoprotein and apolipoprotein A1/B are the independent protective factors for EH in the Kazakh of Xinjiang region. The polymorphisms of eNOS gene rs3918188 and rs7830 loci are not related to EH in the Kazakh of Xinjiang region.     

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 chronic hypoxia on L-Arginine/nitric oxide pathway in rat pulmonary artery

AIM: To study the effect of chronic hypoxia on L-Arginine/NO pathway in rat pulmonary artery. METHODS: Changes in pulmonary artery L-Arginine(L-Arg) transport, nitric oxide synthase (NOS) activity, plasma nitrite level and L-Arg level in HPH rats were investigated. RESULTS: (1) The mean pulmonary arterial pressure (mPAP) and weight ratio of right ventricle to left ventricle and septum (RV/LV+S) of HPH group were higher than those in control group (P＜0.01). (2) Plasma L-Arg level in HPH group was not significantly changed. (3) At low (0.2 mmol/L)or high(5.0 mmol/L)concentration of L-Arg, the velocity of L-Arg transport in HPH group was lower than that in control group (P＜0.05 or P＜0.01). (4) The activity of pulmonary artery tNOS, iNOS and cNOS in HPH group were increased by 38.0%, 32.8% and 53.0%, respectively (P＜0.01), compared with control group. (5) Plasma NO level of HPH group was decreased, which was negative correlation to mPAP and RV/LV+S (P＜0.01). CONCLUSION: The decrease of nitric oxide generation might result from L-Arg transport injury, while pulmonary artery tNOS, iNOS and cNOS activity were enhanced during chronic hypoxia.     

Effects of halothane and sevoflurane on the function,metabolism and Ca2＋-ATPase activity of ischemic myocardium

AIM: To study the effects of 1. 5 MAC halothane and sevoflurane on ischemic myocardium. METHODS: The isolated rat heart were perfused with halothane and sevoflurane and HR, LVEDP, LVDP, +dp/dt, -dp/dt, coronary flow (CF), the myocardial ATP content and Ca²⁺-ATPase activity were determined before and 10 min and 25 min after ischemia. In the meantime, LVP was recorded during 25 min ischemia. RESULTS: 1. 5MAC sevoflurane significantly increased CF in normal isolated rat hearts. Both halothane and sevoflurane depressed myocardial contractile function, increased normal myocardial energy storage. After 10 min ischemia, the decrease of myocardial ATP content were slowed down by halothane and sevoflurane, especially halothane. During 25 min of ischemia, the onset time of contracture was significantly delayed, and the contracture intensity was alleviated by halothane, but not sevoflurane. CONCLUSION: Halothane has better protective effect on ischemic myocardium than sevoflurane through preventing the decrease of myocardial ATP content and Ca²⁺-ATPase activity during ischemia.     

Effects of endothelial nitric oxide synthase gene transfection on cytokines and cAMP production in human phagocytic cells

AIM and METHOD: Human endothelial nitric oxide synthase (eNOS) gene was transfected into human phagocytic cell U937 and the effects of gene transfer on cytokines and cAMP production were observed. RESULTS: A functional eNOS was stably expressed in transfected U937 cells, but NO release was undetectable in intact transfectants. However, eNOS gene expression upregulated tumor necrosis factor-α release and downregulated interleukin-10 and cAMP production in either presence or absence of NOS inhibitor N^ω-monomethyl-L-arginine. CONCLUSION: The function of tranfected eNOS gene product showed cellular speciality. The effector molecule that changed the produced pattern of cytokines and cAMP in phagocytic cells seems not likely the nitric oxide.     

The relaxation of rabbit femoral artery induced by cAMP is partly dependent on nitric oxide

AIM:To determine whether vasorelaxation induced by cAMP is dependent on eNOS activation.METHODS:A constant perfusion model of rabbit femoral artery was used to observe the changes of perfusion pressure before and after intra-arterial infusing different concentrations of dbcAMP(a membrane-permeable cAMP analogue) or forskolin(a direct stimulator of adenyl cyclase) and the effects of NOS inhibitor L-NAME on their actions.RESULTS:Both dbcAMP and forskolin induced concentration-dependent relaxation of rabbit femoral artery bed and NOS inhibitor L-NAME partly inhibited this vasorelaxation.CONCLUSION:Vasorelaxation induced by cAMP is mediated partly through eNOS activation.     

Alteration of pulmonary vascular structure and gaseous molecules in rats with pulmonary hypertension induced by high pulmonary blood flow

AIM: To examine the alteration of pathologic structure and gaseous molecules in rats with pulmonary hypertension induced by high pulmonary blood flow.METHODS: Aortocaval shunting was produced for 11 weeks in rats, and pulmonary hemodynamics was evaluated.Pulmonary vascular micro- and ultra- structure was also examined.Meanwhile,the concentration of plasma nitric oxide (NO) and carbon monoxide (CO) was measured by spectrophotometry.The expression of endothelial nitric oxide synthase (eNOS) and heme oxygenase-1 (HO-1) in pulmonary arteries was detected by immunohistochemistry.RESULTS: After 11- week aortocaval shunting,pulmonary artery mean pressure was significantly increased.Muscularization of small pulmonary vessels and relative medial thickness and area of pulmonary arteries were obviously increased in shunting rats compared with controls.Ultrastructure of intrapulmonary arteries changed obviously in shunting rats.Meanwhile,plasma NO concentration was increased and eNOS expression in pulmonary artery endothelial cells was significantly augmented in rats of shunting group.Plasma carbon monoxide level and HO-1 expression in puomonary artery smooth muscle cells,however,were not altered in shunting rats.CONCLUSIONS: Pulmonary vascular structural remodeling is the important pathologic basis of pulmonary hypertension induced by a left-to-right shunt,and NO other than CO might play an important regulating role in the development of high pulmonary blood flow-induced pulmonary hypertension.     

Renoprotective effects of sesamin on renal hypertensive and hyperlipidemic rats

AIM: To investigate the effects of sesamin on progression of renal injury in renal hypertensive and hyperlipidemic rats (RHHR). METHODS: RHHR was induced by 2K1C and high lipid baitvessel. After 7 weeks of intragastric administration with sesamin, the contents of serum creatinine (Scr), blood urea nitrogen (BUN), 24 h urinary protein excretion (UPE) were measured. In addition, the activity of total antioxidative capacity (T-AOC), superoxide dismutase (SOD), the concentrations of malondialdehyde (MDA), hydrogen peroxide (H2O2), and the nitric oxide synthase (NOS) and nitric oxide (NO) levels in renal homogenate were measured. RESULTS: Compared with the model group, seasamin (in 100 mg·kg-1 and 33 mg·kg-1 groups) evidently decreased the contents of Scr, BUN, UP and the concentration of MDA, iNOS, H2O2 in renal tissure. It also improved the levels of NO, cNOS and activity of SOD, T-AOC in renal tissure. CONCLUSION: Sesamin ameliorates hypertensive and hyperlipidemic-induced renal injury, probably by enhancing antioxidative activity, scavenging hydroxyl radical and restraining iNOS level.     

Preventive effects of aminophylline on the pulmonary hypertension rebound reaction to exposure to NO in the hypoxic pigs

AIM: To evaluate the prophylactic effect of aminophylline on the pulmonary hypertension rebound reaction to exposure to NO in the hypoxic pigs. METHODS: The 10 pigs undergone Swan-Ganz catheter, the mPAP was measured with a Physio-recording instrument and PaO₂ was measured with a blood gas analyzer, when breathing NO for 30 minutes and suddenly stopping breathing NO, administing aminophylline 0.25 g, followed by 30 minutes with room air. The respiratory rate and heart rate were also monitorried with a Hewlett-Packard portable monitor. RESULTS: The mPAP of the acute hypoxic pig was induced significantly after breathing 10^-5 NO. When suddenly stopping breathing NO, the induced mPAP became more and more high, the level of the mPAP in 5 minutes was similar to the values before absorbing NO, the mPAP in 10 minutes was higher than values before absorbing NO, while the level of PaO₂ was lower than the values before absorbing NO; but suddenly stopping breathing NO, administing aminophylline, although the induced mPAP became high, the speed was slower than the controls, the level of the mPAP in 30 minutes still was lower than the values before absorbing NO. CONCLUSION: Aminophylline has preventive effects on the pulmonary hypertension rebound reaction to exposure to NO in the hypoxic pigs.     

Effects of nitric oxide and endothelin on relaxation and contraction of isolated splanchnic vascular strips in cirrhotic rats

AIM: To investigate the different vasoactive effects of nitric oxide (NO) and endothelin (ET) on splanchnic arterial and venous vessels in cirrhotic rats. METHODS: Cirrhosis was induced in Wistar rats by subcutaneously administration of carbon tetrachloride. Maximal relaxation (Rmax) and contraction (Cmax) to NO and ET were determined in vitro using isolated vascular strips prepared from portal vein (PV) and mesenteric artery (MA) of both cirrhotic and normal rats, and EC50 was calculated for effects of NO and ET, respectively. RESULTS: Rmax of PV and MA to sodium nitroprusside (SNP) (releasing NO) were significantly higher in cirrhotic rats (n=8) than those in normal rats (n=7), and EC50 of NO were dramatically lower in cirrhotic rats than those in control (P<0.05,P<0.01). Cmax of PV and MA to ET were significantly decreased in cirrhotics compared with control, and EC50 of ET were obviously increased in cirrhotic rats compared with normal rats (P<0.05,P<0.01). Furthermore, there were significant differences in Rmax, Cmax and EC50 to NO and ET between PV and MA in both of cirrhotic and normal rats, but these differences in cirrhotics were greater than those in control (P<0.05 or P<0.01). CONCLUSION: There are significant different vasoactive effects of NO and ET on splanchnic arterial and venous vessels in cirrhotic rats, and it may play a crucial role in the pathogenesis of portal hypertension.