BACKGROUND AND OBJECTIVES: The octapeptide hormone of the renin-angiotensin system, angiotensin ii, regulates a wide variety of physiological responses including salt and water balance, blood pressure, and vascular tone. Contradictory results have been reported regarding the effects of angiotensin ii on vascular smooth mu-scle cell (VSMC) proliferation. The aim of the present study was to investigate the direct effect of angiotensin ii on the growth of VSMC. MATERIALS AND METHOD: Rat aortic smooth muscle cells were obtained by the combined collagenase and elastase methods. Cells between the 4th and 8th passages were used for the experiments. Cultures were treated daily for 3 days with either angiotensin ii alone or angiotensin ii with equimolar concentrations of saralasin. Incorporated radioactivity of [3H]thymidine and [14C]phenylalanine was measured by liquid scintillation spectrometry. RESULTS: Angiotensin ii increased [14C]phenyalanine incor-poration about 20-30%, and saralasin completely blocked the stimulation by angiotensin ii. However, there was no significant increase in [3H]thymidine incorporation by angiotensin ii stimulation in this study. CONCLUSION: These results suggest that angiotensin ii alone induces cellular hypertrophy but has no detectable mitogenic activity in cultured rat aortic VSMC.
Angiotensin II* ; Angiotensins* ; Animals ; Blood Pressure ; Collagenases ; Hypertrophy ; Muscle, Smooth, Vascular* ; Myocytes, Smooth Muscle ; Pancreatic Elastase ; Radioactivity ; Rats ; Renin-Angiotensin System ; Saralasin ; Spectrum Analysis

Changes of blood pressure, heart rate, ECG, respiration rate and pupil size by intracerebroventricular(ICV) infusion of hypertonic NaCl with 0.04 ml/min for 5 min(total 0.2ml) were observed in urethane-anesthetized rabbits. ICV infusion of 0.75M NaCl produced slight pressor effect (11mmHg) and did not affect other parameters. ICV infusion of 1.5M NaCl began to increase blood pressure from 2~3 min after the infusion and produced maximal increase(24mmHg) at 5~10 min. Then the pressor effect was recovered to the original level at 30~60 min. Change of heart rate by the infusion was not clear, but ST-segment of ECG was markedly depressed. Respiration rate increased about 1.5 times than the control in accordance with the pressor effect and the state was continued even after the recover of the pressor effect. Both pupils dilated markedly and light-reflex was lost. Changes of parameters by ICV infusion of 3.0M NaCl were similar to those by 1.5M NaCl and some rabbits caused severe arrhythmias and died. The purpose of present study is to investigate the mechansim(s) of the pressor effect induced by the ICV infusion of 1.5M NaCl. The pressor effect of 1.5M NaCl was attenuated by the continuous infusion of vasopressin antagonist(20microm/kg/min) but not affected by intravenous treatment with 2mg/kg phentolamine, 2mg/kg propranolol and 1mg/kg chlorisondamine. The pressor effect was not altered with ICV 0.12mg/kg phenoxybenzamine, 0.4mg diltiazem, 0.1mg/kg mecamylamine and 0.2mg/kg atropine. After ICV infusion of 25microg/kg/min of diazepam, however, the pressor effect was completely abolished and restored 3~4 hours after stopping diazepam infusion. The pressor effect was rather potentiated than inhibited in bilateral adrenalectomized or nephrectomized rabbits. Infusion of 2microg/kg/min of saralasin for 10 min in the bliateral adrenalectomized rabbit did not affect the pressor effect at all. These results suggest that hypertensive effect induced by ICV infusion of hypertonic NaCl is mediated by the increase of vasopressin secretion.
Arrhythmias, Cardiac ; Atropine ; Blood Pressure ; Chlorisondamine ; Diazepam ; Diltiazem ; Electrocardiography ; Heart Rate ; Infusions, Intraventricular* ; Mecamylamine ; Phenoxybenzamine ; Phentolamine ; Propranolol ; Pupil ; Rabbits* ; Respiratory Rate ; Saralasin ; Vasopressins

OBJECTIVE: The exact mechanism of angiotensin II to steroidogenesis is still speculative in spite of many researches especially in human and these were performed indirectly with serum or follicular fluid. Under the hypothesis that ovarian RAS increases androgen, decreases progesterone synthesis in normal human ovary, we investigated the exact action of angiotnesin II on human ovary. METHODS: After appliance of angiotensin II and saralasin to the normal human ovarian follicles, we measured sex steroids like progesterone, testosterone, DHEA and enzymes like HSD3beta2, CYP 17 to see the action of angiotensin II and its antagonist, saralasin. The results were analyzed by ANOVA test. RESULTS: Angiotensin II increased androgen synthesis but did not affect progesterone synthesis. There were no difference of HSD 3beta2 mRNA expression in angiotensin II and saralasin group compared with control group. The expression of CYP17 mRNA was increased by angiotensin II but did not reach statistically significant level. CONCLUSION: Angiotensin II could increase androgen production probably via overexpression of CYP17, but had no efffect on progesterone production.
Angiotensin II* ; Angiotensins* ; Dehydroepiandrosterone ; Female ; Follicular Fluid ; Humans* ; Ovarian Follicle* ; Ovary ; Progesterone ; RNA, Messenger ; Saralasin ; Steroid 17-alpha-Hydroxylase ; Steroids ; Testosterone

BACKGROUND: Prostaglandin system is known to participate in manifestation of the renin-angiotensin system. However, role of prostaglandins on the renin-angiotensin system in development of hypertension is not well established. This study was to examine whether the role of prostaglandins is altered in experimental hypertension. METHODS: Two-kidney, one-clip(2KIC) renal hypertension was made by clipping the left renal artery with a silver clip(internal gap of 0.2mm) and deoxycorticosterone acetate (DOCA)-salt hypertension by subcutaneous implantation of DOCA(200mg/kg) strip plus saline(1%) drinking. They were used 3 weeks later. Age-matched normal rats served as a control. Femoral artery was cannulated and arterial blood pressure and heart rate were monitored continuously. RESULTS: 1) In normotensive rats, saralasin infusion(20 microg/kg/min, IV) caused a decrease in mean arterial pressure without significant alterations in heart rate. Indomethacin-pretreatment(10mg/kg, IP) abolished the depressor response to saralasin. 2) The depressor response to saralasin was more marked in renal hypertensive rats than in normotensive rats. The magnitude of maximum decrease in blood pressure, however, was comparable between the hypertensive and normotensive rats. Indomethacin-pretreatment did not affect the depressor response to saralasin in renal hypertensive rats. 3) In DOCA-salt hypertensive rats, saralasin infusion rather caused an increase in mean arterial pressure without significant alterations in heart rate. The pressor response to saralasin was not affected by indomethacin-pretreatment. CONCLUSION: These results indicate that prostaglandin system may modify renin-angiotensin system in normotensive rats. It is suggested that mechanisms other than prostaglandin system participate in the full-blown manifestation of renin-angiotensin system in 2KIC renal hypertensive rats.
Animals ; Arterial Pressure ; Blood Pressure ; Desoxycorticosterone ; Drinking ; Femoral Artery ; Heart Rate ; Hypertension ; Hypertension, Renal ; Prostaglandins I ; Prostaglandins* ; Rats* ; Renal Artery ; Renin-Angiotensin System* ; Saralasin ; Silver

BACKGROUNDThe decreased degradation of extra-cellular matrix proteins plays an important role in the onset of diabetic nephropathy. Matrix metalloproteinase-9 (MMP-9) and tissue inhibitor of metalloproteinase-1 (TIMP-1), which are members of the matrix metalloproteinase family, are associated with this process. Angiotensin II (AII) plays an important role in the development of diabetic nephropathy also. This research aimed to investigate the effect of angiotensin II receptor blocker on glucose-induced mRNA expressions of MMP-9 and TIMP-1 in rat mesangial cells.

METHODSRat mesangial cells were cultured and divided into 5 groups: normal glucose (group NG), high glucose (group HG), group NG + AII, NG + AII + saralasin (group NG + AII + S, saralasin is the AII receptor blocker) and HG + saralasin (group HG + S). After the cells were incubated for 24 hours, AII concentrations in the supernatant were measured by radioimmunoassay and the expression of MMP-9 and TIMP-1 mRNA was assayed by reverse transcription-polymerase chain reaction (RT-PCR).

RESULTSAII concentrations were higher in group HG ((56.90 +/- 13.54) pg/ml) and group HG + S ((51.30 +/- 5.96) pg/ml) than in group NG ((37.89 +/- 8.62) pg/ml, P < 0.05), whereas there was no significant difference between group HG and group HG + S. The expression of MMP-9 mRNA and MMP-9/TIMP-1 mRNA ratio in group NG + AII (MMP-9, 0.33 +/- 0.04; MMP-9/TIMP-1, 0.40 +/- 0.06) and group HG (MMP-9, 0.36 +/- 0.02; MMP-9/TIMP-1, 0.45 +/- 0.03) were decreased more significantly than those in group NG (MMP-9, 0.72 +/- 0.02; MMP-9/TIMP-1, 1.21 +/- 0.07). These values in group NG + AII + S (MMP-9, 0.71 +/- 0.02; MMP-9/TIMP-1, 1.18 +/- 0.05) were higher than those in group NG + AII, and the values in group HG + S (MMP-9, 0.71 +/- 0.02; MMP-9/TIMP-1, 1.16 +/- 0.05) were higher than those in group HG (all were P < 0.05). TIMP-1 mRNA expression was increased more significantly in group NG + AII (0.81 +/- 0.03) and group HG (0.80 +/- 0.03) than in group NG (0.59 +/- 0.02), but it was lower in group NG + AII + S (0.60 +/- 0.01) than in group NG + AII and also lower in group HG + S (0.61 +/- 0.01) than in group HG (all were P < 0.05).

CONCLUSIONSHigh glucose stimulates AII production. Both high glucose and AII induce a decrease in MMP-9 mRNA expression and MMP-9/TIMP-1 mRNA ratio as well as an increase in TIMP-1 mRNA expression, which can be reversed by saralasin, suggesting that high glucose can aggravate impaired matrix degradation by altering gene expression of MMP-9 and TIMP-1 and that the effect of high glucose may be mediated by AII.

Angiotensin II Type 1 Receptor Blockers ; pharmacology ; Angiotensin Receptor Antagonists ; Animals ; Cells, Cultured ; Gene Expression ; drug effects ; Glucose ; pharmacology ; Matrix Metalloproteinase 9 ; genetics ; Mesangial Cells ; cytology ; drug effects ; metabolism ; RNA, Messenger ; genetics ; metabolism ; Rats ; Reverse Transcriptase Polymerase Chain Reaction ; Saralasin ; pharmacology ; Tissue Inhibitor of Metalloproteinase-1 ; genetics