Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0004135 (ATM)
 13,001 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The transgenic rat (TGR) (mRen-2)27 is said to have low circulating active renin values in plasma and little or no renin gene expression in the kidney. Nevertheless, intrarenal angiotensin II-related effects appear to be responsible for the rightward shift in pressure-natriuresis curves of TGR. To clarify the role of the intrarenal renin-angiotensin system in modulating TGR pressure-natriuresis, TGR were given lifelong lisinopril by treating TGR and their mothers before conception. Rat and mouse renin, AT1 receptor, and angiotensinogen gene expression in the kidneys were studied with in situ hybridization. Neural and endocrine regulatory differences between TGR and Sprague-Dawley Hannover (SDH) rats were eliminated by renal denervation and infusion of vasopressin, aldosterone, 17-OH corticosterone, and norepinephrine. TGR with lisinopril had blood pressures similar to SDH. In TGR with lisinopril, the pressure-natriuresis curve was shifted leftward but not quite to the values observed in SDH given lisinopril. The histology of lisinopril-treated TGR was indistinguishable from normal SDH. Lisinopril increased rat renin and angiotensinogen gene expression both in SDH and TGR, but it did not influence mouse renin gene expression in TGR. Discontinuing lisinopril increased blood pressure in TGR and shifted the pressure-natriuresis relationship rightward. Thus, the components of the endogenous renin-angiotensin system and the mouse renin transgene were present and expressed in kidneys of TGR. The rat gene components responded to lisinopril as expected, but the mouse renin transgene expression was not influenced. Lisinopril normalized TGR blood pressure; however, a detectable leftward shift in pressure-natriuresis remained. These studies underscore the role of angiotensin-mediated effects of the mouse renin transgene in terms of shifting pressure-natriuresis in TGR.
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PMID:Lifelong angiotensin-converting enzyme inhibition, pressure natriuresis, and renin-angiotensin system gene expression in transgenic (mRen-2)27 rats. 891 71

Recent studies have shown that angiotensin-(1-7) [Ang-(1-7)] interacts with kinins and augments bradykinin (BK)-induced vasodilator responses by an unknown mechanism. In this study, we evaluated whether the potentiation of the BK-induced vasodilation by Ang-(1-7) may be attributable to inhibition of BK metabolism, release of nitric oxide, or both. Isometric tension was measured in intact canine coronary artery rings suspended in organ chambers. 125I-[Tyr0]-BK metabolism was determined in vascular rings by assessing the degradation of the peptide by high-performance liquid chromatography. Ang-(1-7) augmented the vasodilation induced by BK in a concentration-dependent manner in rings preconstricted with the thromboxane analog U46619. The EC50 of BK (2.45 +/- 0.51 nmol/L versus 0.37 +/- 0.08 nmol/L) was shifted leftward by 6.6-fold in the presence of 2 mumol/L concentration of Ang-(1-7). The response was specific for BK. since Ang-(1-7) did not augment the vasodilation induced by either acetylcholine (0.05 mumol/L) or sodium nitroprusside (0.1 mumol/L). Moreover, neither angiotensin I nor angiotensin II (Ang II) duplicated the augmented BK response of Ang-(1-7). Pretreatment of vascular rings with the nitric oxide synthase inhibitor, N omega-nitro-L-arginine (L-NA; 100 mumol/L) completely abolished the effects of Ang-(1-7) on BK-induced vasodilation whereas pretreatment with indomethacin (10 mumol/L) was without effect. The potent specific BK B2 receptor antagonist, Hoe 140. nearly abolished the BK and the Ang-(1-7) potentiated responses at 2 mumol/L, whereas at a lower concentration (20 nmol/L) Hoe 140 shifted the response curve to the right for both Ang-(1-7) and vehicle; however, the augmented response to Ang-(1-7) persisted. Preincubation of vascular rings with 20 mumol/L of the AT1 (CV11974), AT2 (PD123319), or nonselective (Sar1 Thr8-Ang II) receptor antagonists had no significant effect on the Ang-(1-7)-enhanced vasodilator response to BK. Lisinopril (2 mumol/L) significantly enhanced the BK-induced vasodilator response while at the same time it abolished the synergistic action of Ang-(1-7) on BK. In addition, pretreatment with 2 mumol/L Ang-(1-7) significantly inhibited the degradation of 125I-[Tyr0]-BK and the appearance of the BK-(1-7) and BK-(1-5) metabolites in coronary vascular rings. Ang-(1-7) inhibited purified canine angiotensin converting enzyme activity with an IC50 of 0.65 mumol/L. In conclusion. Ang-(1-7) acts as a local synergistic modulator of kinin-induced vasodilation by inhibiting angiotensin converting enzyme and releasing nitric oxide.
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PMID:Angiotensin-(1-7) augments bradykinin-induced vasodilation by competing with ACE and releasing nitric oxide. 903 33

Myofibroblasts (myoFb) are cells responsible for fibrous tissue formation in injured systemic organs such as the heart. Cultured myoFb, obtained from rat cardiac scar tissue, express genes that encode components requisite for angiotensin (Ang) II generation, which in turn regulates myoFb collagen turnover in an autocrine/paracrine manner. In this study, we tested the hypothesis that these wound-healing fibroblast-like cells and locally generated Ang II are involved in other repairing tissue. To test this hypothesis, we used a granuloma pouch model, where a subcutaneous air sac is created followed by injection of croton oil. Pouch tissue was collected at days 4, 7, 14 and 21. The presence of myoFb was determined by immunohistochemical alpha-smooth muscle actin (alpha-SMA) labeling and collagen accumulation by picrosirius red staining. Angiotensin converting enzyme (ACE) and Ang II receptor binding were detected by in vitro quantitative autoradiography using 125I-351A and 125I[Sar1, Ile8]Ang II, respectively, while Ang II receptor subtype was defined by displacement studies using either an AT1 (losartan) or AT2 (PD123177) receptor antagonist. Cells expressing ACE were determined by immunohistochemistry. Ang II content in pouch tissue was measured by radioimmunoassay following HPLC separation while its capacity to generate Ang II was assessed in tissue bath, with and without exogenous Ang I or lisinopril, an ACE inhibitor. Collagen accumulation in pouch tissue was examined by determining hydroxyproline content in response to lisinopril, AT1 or AT2 receptor antagonists (losartan or PD123177). In pouch tissue, we found: (1) myoFb at day 4 which became more extensive at days 7, 14 and 21; (2) morphologic evidence of collagen deposition evident at day 4, which gradually became more extensive thereafter; (3) ACE and Ang II receptor binding was evident at day 4 and remained invariant on days 7, 14 and 21; (4) the predominant Ang II receptor subtype expressed was AT1; (5) myoFb express ACE and AT1 receptors; (6) picogram quantities of Ang II (per g tissue) was evident on days 7, 14 and 21; and (7) Ang II was generated from Ang I substrate. Lisinopril and losartan, but not PD123177, significantly attenuated pouch weight and accumulation of collagen. Thus, in this model of cutaneous repair, the appearance of myoFb is associated with Ang II generation that regulates fibrogenesis by AT1 receptor binding. Signals involved in the appearance of myoFb remain uncertain. Further studies are required to address the regulation of Ang II generation in pouch tissue of the rat.
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PMID:Fibrous tissue and angiotensin II. 928 34

We have previously shown that cough potentiation induced by intravenous administration of the AT1 receptor antagonist losartan is lower than that induced by the ACE inhibitor lisinopril in anesthetized and awake rabbits. Since losartan and lisinopril cross the blood-brain barrier, their central action on the cough reflex can be hypothesized. Mechanical stimulation of the tracheobronchial tree and citric acid inhalation were used to induce cough reflex responses in pentobarbital sodium-anesthetized, spontaneously breathing rabbits. Bilateral microinjections (30-50 nl) of losartan (5mM), lisinopril (1mM), bradykinin (0.05 mM), HOE-140 (0.2mM, a bradykinin B2 receptor antagonist) and CP-99,994 (1mM, an NK1 receptor antagonist) were performed into the caudal nucleus tractus solitarii, the predominant site of termination of cough-related afferents. Lisinopril, but not losartan increased the cough number. This effect was reverted by HOE-140 or CP-99,994. Cough potentiation was also induced by bradykinin. The results support for the first time a central protussive action of lisinopril mediated by an accumulation of bradykinin and substance P.
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PMID:The cough reflex is upregulated by lisinopril microinjected into the caudal nucleus tractus solitarii of the rabbit. 2623 77

Chronic heart failure (CHF) is associated with endothelial dysfunction. Activation of the renin-angiotensin-aldosterone system (RAAS) is believed to be important in the deterioration of endothelial dysfunction in CHF through stimulation of oxidative stress. Whereas angiotensin-converting enzyme inhibitors (ACE-I) improve endothelial function in CHF, the effects of angiotensin II AT1-receptor blockers (ARB) are less well established. Therefore we compared the effects of the ACE-I lisinopril vs. the ARB candesartan on endothelial dysfunction in a rat model of CHF. CHF was induced by myocardial infarction (MI) after coronary ligation. Two weeks after MI, daily treatment with lisinopril (2 mg/kg) or candesartan cilexetil (1.5 mg/kg) was started. After 13 weeks, rats were sacrificed and endothelial function was determined by measuring acetylcholine (ACh)-induced vasodilation in aortic rings, with selective presence of the nitric oxide synthase (NOS)-inhibitor NG-monomethyl-L-arginine (L-NMMA) to determine the contribution of nitric oxide (NO). ACh-induced vasodilation was attenuated in untreated MI (-50%) compared with control rats. This was in part due to an impaired contribution of NO (-49%). Lisinopril and candesartan cilexetil fully normalised ACh-induced dilation, including the part mediated by NO. Chronic RAAS-blockade with lisinopril and candesartan cilexetil normalised endothelial function in CHF in a comparable way. The effect of both treatments included the increase of the NO-mediated dilation, further indicating the important role of oxidative stress in the relationship between the RAAS and endothelial dysfunction in CHF.
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PMID:Improvement of endothelial dysfunction in experimental heart failure by chronic RAAS-blockade: ACE-inhibition or AT1-receptor blockade? 2809 51