Effect of angiotensin II receptor blocker on glucose-induced mRNA expressions of matrix metalloproteinase-9 and tissue inhibitor of metalloproteinase-1 in rat mesangial cells / 中华医学杂志(英文版)

<p><b>BACKGROUND</b>The 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.</p><p><b>METHODS</b>Rat 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).</p><p><b>RESULTS</b>AII 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).</p><p><b>CONCLUSIONS</b>High 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.</p>

Hipertensión arterial experimental por medio del uso de un bloqueador competitivo de angiotensina II / Experimental arterial hypertension by using an angiotensin II competitive blocker

Se utilizó la saralasina, un bloqueador competitivo de la angiotensina II, con el propósito de incrementar el flujo sanguíneo renal y la tasa de filtración glomerular, para estudiar sus posibles consecuencias tubulares y sobre la presión arterial. Fueron divididas 40 ratas de la línea Wistar, inicialmente normotensas, en 4 grupos: saralasina, supresión, grupos controles corrieron paralelos. Se les realizaron a todos mediciones de variables hemodinámicas sistémicas y renales, así como morfométricas del riñón. Los resultados apoyaron la hipótesis de la participación de la hiperfunción tubular en la génesis de la hipertensión arterial primaria y propusieron un nuevo modelo de hipertensión arterial experimental en ratas

The role of angiotensin II to regulation of steroidogenic pathway in human ovarian follicle / 대한산부인과학회지

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.

Influência dos subtipos dos receptores da angiotensina II do núcleo paraventricular sobre as respostas fisiológicas induzidas pela angiotensina II injetada na área septal medial / Influence of angiotensin II receptor subtypes of the paraventricular nucleus on the physiological responses induced by angiotensin II injection into the medial septal area

OBJECTIVE: We determined the effects of losartan and PD 123319 (antagonists of the AT1 and AT2 angiotensin receptors, respectively), and [Sar , Ala8] ANG II (a relatively peptide antagonist of angiotensin receptors) injected into the paraventricular nucleus (PVN) on water and 3 percent NaCl intake, and the diuretic, natriuretic, and pressor effects induced by administration of angiotensin II (ANG II) into the medial septal area (MSA) of conscious rats. METHODS: Holtzman rats were used . Animals were anesthetized with tribromoethanol (20 mg) per 100 grams of body weight, ip. A stainless steel guide cannula was implanted into the MSA and PVN. All drugs were injected in 0.5-mul volumes for 10-15 seconds. Seven days after brain surgery, water and 3 percent NaCl intake, urine and sodium excretion, and arterial blood pressure were measured. RESULTS: Losartan (40 nmol) and [Sar , Ala8] ANG II (40 nmol) completely eliminated whereas PD 123319 (40 nmol) partially blocked the increase in water and sodium intake and the increase in arterial blood pressure induced by ANG II (10 nmol) injected into the MSA. The PVN administration of PD 123319 and [Sar , Ala8] ANG II blocked whereas losartan attenuated the diuresis and natriuresis induced by MSA administration of ANG II. CONCLUSION: MSA involvement with PVN on water and sodium homeostasis and arterial pressure modulation utilizing ANGII receptors is suggested

Effects of Angiotensin II on the Growth of Vascular Smooth Muscle Cells

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.

Role of endothelium in angiotensin II formation by the rat aorta and mesenteric arterial bed

We investigated the angiotensin II (Ang II)-generating system by analyzing the vasoconstrictor effect of Ang II, angiotensin I (Ang I), and tetradecapeptide (TDP) renin substrate in the abscence and presence of inhibitors of the renin-angiotensin system in isolated rat aortic rings and mesenteric arterial beds with and without functional endothelium. Ang II, Ang I, and TDP elicited a dose-dependent vasoconstrictor effect in both vascular preparations that was completely blocked by the Ang II receptor antagonist saralasin (50 nM). The angiotensin converting enzyme (ACE) inhibitor captopril (36 muM) completely inhibited the vasoconstrictor effect elicited by Ang I and TDP in aortic rings without affecting that of Ang II. In contrast, captopril (36 muM) significantly reduced (80-90 percent) the response to bolus injection of Ang I, without affecting those to Ang II and TDP in mesenteric arteries. Mechanical removal of the endothelium greatly potentiated (70-95 percent) the vasoconstrictor response to Ang II, Ang I, and TDP in aortic rings while these responses were unaffected by the removal of the endothelium of mesenteric arteries with sodium deoxycholate infusion. In addition, endothelium disruption did not change the pattern of response elicited by these peptides in the presence of captopril. These findings indicate that the endothelium may not be essential for Ang II formation in rat mesenteric arteries and aorta, but it may modulate the response to Ang II. Although Ang II formation from Ang I is essentially dependent on ACE in both vessels, our results suggest the existence of an alternative pathway in the mesenteric arterial bed that may play an important role in Ang II generation from TDP in resistence but not in large vessels during ACE inhibition.

Role of Prostaglandins on the Renin-Angiotensin System in Normotensive and Hypertensive Rats

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.

The role of angiotensin AT1 receptors in the diuretic, natriuretic, kaliuretic and blood pressure responses induced by angiotensin II activation of the median preoptic nucleus in conscious rats

We determined the effects of two classical angiotensin II (ANG II) antagonists, [Sar1, Ala8]-ANG II and [Sar1, Thr8]-ANG II, and losartan (a nonpeptide and selective antagonist for the AT1 angiotensin receptors) on diuresis, natriuresis, kaliuresis and arterial blood pressure induced by ANG II administration into the median preoptic nucleus (MnPO) of male Holtzman rats weighing 250-300 g. Urine was colected in rats submitted to a water load (5 percent body weight) by gastric gavage, followed by a second water load (5 percent body weight) 1 h later. The volume of the drug solutions injected was 0.5 µl over 10-15 s. Pre-treatment with [Sar1, Ala8]-ANG II (12 rats) and [Sar1, Thr8]-ANG II (9 rats), at the dose of 60 ng reduced (13.7 +/- 1.0 vs 11.0 +/- 1.0 +/- 1.2, respectively), whereas losartam (14 rats) at the dose of 160 ng totally blocked (13.7 +/- 1.0 vs.7.6 +/- 1.5) the urine excretion induced by injection of 12 ng of ANG II (14 rats)...

Sudies About the Pressor Response to Intracerebroventricular Infusion of Hypertonic NaCl in Rabbits

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.

Effect of glomerulopressin on GFR of rats, role of cyclooxygenase inhibitors and saralasin

En trabajos anteriores se ha demostrado que la glomerulopresina aumenta la filtración glomerular (FG) en sapos, ratas y perros. El efecto de la glomerulopresina es bloqueado por inhibidores de la ciclooxigenasa en varios sistemas. Este trabajo se llevó a cabo con el propósito de estudiar si los inhibidores de la ciclooxigenasa y el bloqueador de los receptores de Ang II, saralasina, impiden el efecto de la glomerulopresina sobre la FG de la rata. Se midió la depuración de inulina en ratas infundidas durante todo el experimento con indometacina o meclofenamato o con saralasina por la vena yugular. Se consideró un período de control durante el cual se infundió Krebs-Ringer-Bicarbonato (KRB) por la arteria femoral y un período experimental durante el cual, en alguns grupos, se cambió la infusión de KRB por la de glomerulopresina. Los inhibidores de la ciclooxigenasa y la saralasina impidieron el aumento de la FG producido por la glomerulopresina. Parece razonable proponer que la glomerulopresina puede aumentar la FG sólo cuando los receptores de la Ang II están libres y que su acción es mediada por la síntesis de prostaglandinas

Hypertonic saline resuscitation is prevented by intracerebroventricular saralasin but not by captopril

Hypertonic saline resuscitation (HR, 7.5% NaCl, 4 ml/Kg) effectively reverts severe hemorrhage, but a central neural component is probvably involved in the survival response. This experiment examines the role of central angiotensinergic pathways in the hemorrhage-hypertonic resuscitation interaction. Severely bled (43ñ 2 ml/Kg) pentobarbital-anesthetized dogs with chromically imnplanted cerebral ventricular cannulae were resusucitated with 4 ml/Kg 7.5% NaCl, iv 10 min after intracerebroventricular injection of 0.5 ml normal saline (CT), 159 µg saralasin (in 0.5 ml saline, SR), or 10 mg captopril (in 0.5 ml salaine, CP). ALL 10 SR-treated dogs died 2-6 h after HR. Their arterial pressure and cardiac index initially recovered to near pre-hemorrhage levels, but bradually decreased thereafter, base excess remaining ar severe metabolic acidosis levels throughout, al CT-and 8/10CP-treated dogs survived indefinitely,, with near normal arterial pressure, cardiac, index and base excess levels. It is there fore concluded that the inhibition of central angiotensinergic sites with the competitive antagonist saralasin effectively prevents survival after HR, whereas inhibition of angiotensin converting enzyme by captopril in cerebrospinal fluid is virtuallly ineffective

Effect of Ca++ channel blockers and saralasin on angiotensin II induced contraction in rabbit aortic strip.

To investigate the role of calcium in angiotensin II (A II) induced contractions in rabbit aortic strip, the action of verapamil, nifedipine, cinnarizine and saralasin was studied. The cumulative dose response curves obtained with A II shifted to right with increasing concentrations of all these four agents. The antagonism was noncompetitive. The pD'2 value of saralasin was 8.49 of nifedipine, 8.15 and or verapamil 7.92. Cinnarizine which mainly acts at intracellular site had pD'2 value 5.54. The results indicate that A II induced contractions critically depend on entry of calcium through channels which appear to be closely associated with angiotensin receptors.