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.     

The gaseous signaling molecules and their roles in pathophysiological processes in the prostate

Endogenous NO and CO have been identified in the recent years as signaling molecules and act as the messengers in the body. Both of them have identical characteristics in the mechanism of production and action. Many evidences indicated that NO and CO play important roles in physiological and patho physiological processes in the prost ate. This review highlights the current ideas on localization and function of them in the prostate. We also discussed the relationship between the gaseous messengers and the prostat ic diseases.     

Intermedin inhibits pulmonary collagen synthesis in rats with pulmonary hypertension induced by high pulmonary blood flow

AIM: To explore the regulatory effect of intermedin (IMD) on pulmonary collagen synthesis and accumulation in rats with pulmonary hypertension induced by high pulmonary blood flow.METHODS: Healthy male SD rats (n=20) were randomly divided into control group (n=7), shunt group (n=7) and shunt with IMD group (n=6). The shunting of abdominal aorta and inferior vena cava was produced in rats of shunt group and shunt with IMD group. After 8 weeks, IMD was administered into the rats of shunt with IMD group subcutaneously by mini-osmotic pump for 2 weeks. Mean pulmonary artery pressure (mPAP), relative medial thickness (RMT) of pulmonary arteries, contents of hydroxyproline, collagen type I and III, bone morphogenetic protein-2 (BMP-2), and the mRNA expression of procollagen I and III in lung tissues were measured and compared. RESULTS: Compared with control group, mPAP and RMT of medium and small pulmonary arteries in the rats of shunt group were significantly increased. Meanwhile, the lung hydroxyproline, collagens I and III and BMP-2 contents, and the mRNA expression of lung procollagen I and III were all significantly increased compared with control group. However, IMD significantly decreased mPAP, alleviated the changes of pulmonary vascular micro-structure, decreased the collagen accumulation and pulmonary tissue homogenate BMP-2 contents, and inhibited the mRNA expression of procollagen I and III in the lung tissue of shunting rats.CONCLUSION: IMD plays a protective role in the development of pulmonary hypertension and pulmonary vascular structural remodeling induced by high blood flow by inhibiting pulmonary collagen synthesis and accumulation, possibly in association with the BMP-2 pathway.     

The acute inhibitory effect of adrenomedullin on hypoxia-induced pulmonary hypertension in rats

AIM:The aim of this study is to investigate the acute inhibitory effects of adrenomedullin(ADM_1-52) on hypoxia pulmonary hypertension and its influence on systemic blood pressure.METHODS:Thirty-six male Wistar rats were divided into two groups. Eighteen were exposed to hypoxia for 21 days as hypoxic pulmonary hypertension group,and another eighteen were kept in ambient as control group. Each group were divided into three subgroups which were injected intravenously with ADM 0.1 nmol/kg, 0.3 nmol/kg, 1 nmol/kg, respectively,then hemodynamic parameters were recorded. Plasma cyclic adenosine 3,5,-monophosphate (cAMP) was measured by radioimmunoassay before,during and after injection of 0.3nmol/kg adrenomedullin(ADM_1-52).RESULTS:Mean pulmonary arterial pressure (mPAP)in the hypoxia and control rats treated with ADM decreased, the fall in hypoxia rats is more obviously than control(P＜0.05), ADM (0.1-0.3 nmol/kg) produced dose-related reductions in mPAP in hypoxia rats(P＜0.05). Mean systemic blood pressure(mSBP) of the rats in both groups decreased in a does-dependent manner, and it was more obvious in control rats. Plasma cAMP is higher in hypoxia group than that in control group.CONCLUSION:ADM depresses the rat hypoxia pulmonary hypertension in short term through, at least partly, cAMP-dependent mechanism.     

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.     

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.     

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.     

Relationship between expression of heme oxygenase-1 mRNA and pulmonary hypertention induced by hypoxic hypercapnia

AIM: To study the effect of chronic hypoxic hypercapnia on expression of heme oxygenase-1 (HO-1). METHODS: Sprague-Dawley rats were randomly divided into three groups: control group(A),hypoxic hypercapnic group(B), hypoxic hypercapnia+hemin group(C). HO-1 and HO-1 mRNA were observed in pulmonary arterioles by the technique of immunohistochemistry and in situ hybridization. RESULTS: ① mPAP and weight ratio of right ventricle (RV) to left ventricle plus septum (LV+S) were significantly higher in rats of B group than those of A and C group (P<0.01). Differences of mCAP were not significant in three groups(P>0.05). ② Blood CO concentration was significantly higher in rats of B group than that of A group (P<0.01), it was much higher in C group than that of B group(P<0.01). ③ Light microscopy showed that vessel well area/total area (WA/TA), density of medial smooth muscle cell (SMC) and media thickness of pulmonary arterioles were much higher in rats of B group than those of A and C group (P<0.01). ④ The observation by electron microscopy showed proliferation of medial smooth muscle cells and collageous fibers of pulmonary arterioles in rats of B group, hemin could reverse the changes mentioned above. ⑤ HO-1 and HO-1 mRNA in pulmonary arterioles was significantly higher in rats of B group than those of A group(P<0.01), and they were significantly higher in rats of C group than those of B group (P<0.01). CONCLUSION: Expression of HO-1 mRNA and HO-1 in pulmonary arterioles was enhanced by hypoxic hypercapnia. Hemin partly inhibited pulmonary hypertension and pulmonary vessel remodeling by enhancing the expression of HO-1 mRNA and HO-1.     

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.     

Role of hydrogen sulfide in acute lung injury induced by ischemia-reperfusion of hind limbs in rats

AIM: To explore the role of endogenous and exogenous hydrogen sulfide (H₂S) in acute lung injury (ALI) induced by ischmia-reperfusion (IR) of hind limbs in rats.METHODS: A Sprague-Dawley rat model of acute lung injury was induced by ischemia of the hind limbs for 4 h and reperfusion for another 4 h. The rats (n=120) were randomly divided into 4 groups: control, IR, NaHS (H₂S donor)+IR, and propargylglycine +IR. The animals were sacrificed after reperfusion. Lung weight/body weight ratio (LW/BW) was measured and calculated. Morphological changes of the lung tissues were observed. The concentrations of H₂S, nitric oxide (NO) and carbon monoxide (CO) in plasma were tested. The content of malondialdehyde (MDA), the activity of CSE, inducible nitric oxide synthase (iNOS) and hemeoxygenase (HO) in the lungs were determined. The polymorpho-nuclear neutrophils(PMN) and protein content in bronchoalveolar lavage fluid(BALF) were also measured. The correlation of H₂S content with the above indices was analyzed.RESULTS: Compared with control group, severe injuries of the lung tissues, raised LW/BW, MDA concentration, PMN and protein contents in BALF were observed in IR group. Limb IR also made a drop in the concentration of plasma H₂S and the activity of lung CSE, while the activity of iNOS and HO in the lung tissues and the levels of plasma NO and CO increased. Administration of NaHS before IR attenuated the changes induced by IR, while pre-administration of PPG exacerbated the IR injuries and increased the plasma NO level and lung iNOS activity. The H₂S content was positively correlated with CSE activity, CO content and HO-1 activity (P<0.01), and negatively correlated with the other indices (P<0.01).CONCLUSION: Down-regulation of H₂S/CSE is involved in the pathogenesis of acute lung injury induced by IR. Endogenous and exogenous H₂S protects against lung injuries. The anti-injury effects of H₂S are related with its anti-oxidative activity to attenuate the inflammatory over-reactions in the lung induced by PMN. Down-regulation of NO/iNOS system and up-regulation of CO/HO-1 system by H₂S are also involved in the process of anti-injury to ALI.     

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.     

Expression of MMP-2 mRNA and MMP-9 mRNA in pulmonary arterioles ofrats with pulmonary hypertension induced by chronic hypoxia hypercapnia

AIM:To investigate the expression of matrix metalloproteinases(MMPs) in pulmonary arterioles of rats with chronic hypoxia and hypercapnia-induced pulmonary hypertension.METHODS:MMP-2, MMP-9 and MMP-2 mRNA, MMP-9 mRNA were observed in pulmonary arterioles by the techniques of immunohistochemistry and in situ hybridization.RESULTS:①The mean pulmonary artery pressure (mPAP) and weight ratio of right ventricle to left ventricle and septum (RV/LV+S) of hypoxia-hypercapnia groups were higher than those of normal control group (P＜0.01). ②Light microscopy showed that vessel wall and media of pulmonary arterioles were thicker in rats of hypoxia-hypercapnia groups than normal control group. There were vessel smooth muscle cell hypertrophy, vessel cavity straitness in hypoxia-hypercapnia group, but no same performance was found in normal control group. ③The expression of MMP-2, MMP-9 and MMP-2 mRNA, MMP-9 mRNA in pulmonary arterioles were significantly higher in rats of hypoxia-hypercapnia groups than control group (P＜0.01).CONCLUSION:Expression of matrix metalloproteinases in pulmonary arterioles is enhanced by hypoxia hypercapnia. This may be involved in pulmonary vascular remodeling in rats with pulmonary hypertension.     

The kinetic alteration of nitric oxide formation in the lungs in the development of pulmonary fibrosis of rats

AIM: To observe the kinetic alteration of nitric oxide formation in the lungs in the development of pulmonary fibrosis in the rat. METHODS: The contents of hydroxyproline in the lungs, NO₂^-/NO₃^- (nitrite/nitrate) in out-flowing and in-flowing pulmonary blood (OPB, IPB) were assayed on the day 7, 14, 21, 30 and 70 after intratracheal administration of bleomycin A₅ . The content of NO₂^-/NO₃^- in supernatants of culture of the alveolar macrophages (AMs) and the amount of iNOS positive stain cells in lung tissue section were also observed in the rat on 14th day after-bleomycin A₅ administration. RESULTS: The content of lung hydroxyproline had no change on the 7th day, increased on the 14th day (P＜0.05), increased significantly on the 21th day, 30th day and 70th day post-bleomycin A₅ compared with control rats. On the 7th day and 14th day, the content of NO^- ₂ /NO₃^- increased in OPB and decreased in IPB (P＜0.01). On the 21th day, the content of NO₂^-/NO₃^- abated in OPB (P＞0.05) but still decreased in IPB (P＜0.01). On the 30th day and the 70th day, the NO₂^-/NO₃^- level recovered both in OPB and IPB. AMs from rats on the 14th day post-bleomycin A₅ showed significant elevation (P＜0.01) in NO₂^-/NO₃^- level. The amount of iNOS positive stain cells increased in rats on the 14th day post-bleomycin A₅. CONCLUSION: The amount of NO in the lungs was high in the initial phase of fibroproliferative reaction induced by bleomycin A₅ ,and these might be associated with the enhanced ability of AMs to release NO and the increased amount of iNOS.     

Effects of nitric oxide on hepatic encephalopathy in cirrhotic rats induced by LPS

AIM: To investigate the effects of nitric oxide (NO) on hepatic encephalopathy in cirrhotic rats induced by LPS. METHODS: The cirrhotic model of rats was established by complex pathogeny. Since the end of the 8 th week, the rats were intragastrically-infused with 0.9% salt, L-arginine(L-arg) and LNNA respectively for 2 weeks.The hepatic encephalopathy in cirrhotic rats were induced by 3 mg/kg LPS (ip) 4 hours before the rats were sacrificed. RESULTS: The normal behaviors and electroencephalograph were appeared in L-arg group. LNNA group showed hepatic encephalopathy. The content of NO₂^-/NO₃^- of brain tissue was markedly higher in L-arg group than LNNA group(P<0.05), but the content of histamine in brain tissue was lower in L-arg group than LNNA group(P<0.05). There was a negative correlation between the content of histamine in brain tissue and the content of NO₂^-/NO₃^- of brain tissue. CONCLUSION: NO can prevent hepatic encephalopathy in cirrhotic rats induced by LPS.     

Alteration of leukocyte iNOS-mRNA expression in rat with diabetic mellitus induced by streptozocin

AIM: To clarify the relationship between expression of leukocyte iNOS-mRNA and pancreatic islet function in the diabetic rats induced by streptozocin (STZ). METHODS: Wistar rats were randomly divided into the control group (n=10) and the diabetic group (n=15). Expression of iNOS-mRNA in the peripheral blood leukocyte, liver and lung were detected with in situ hybridization and the blood sugar and insulin were also measured. RESULTS: It showed that the blood glucose content increased from (8.95±1.80) to (22.84±4.90) mmol·L^-1, however, the plasma insulin content decreased from (81.76±2.12) to (58.92±18.20) mU·L^-1 at the third day after the β cell was disfunctioned by STZ injection. No expression of leukocyte iNOS-mRNA in normal rat was detected. The percent rate of positive cells were significantly increased in the rats with diabetes. CONCLUSION: The expression of leukocyte iNOS-mRNA is positively related to the damage of β cells caused by STZ.     

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.