Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:4.6.1.1 (adenylate cyclase)
 19,190 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Experiments were performed in male Wistar rats with renovascular hypertension (167 +/- 4.2 mmHg) produced by clipping the renal artery for a 3-wk period (2-kidney, 1-clip Goldblatt). The results were compared with those obtained in age-matched normotensive controls. Hypertension of 3-wk duration elicited a significant increase in ventricular weight (1.01 +/- 0.02 g) with respect to the controls (0.82 +/- 0.01 g) but had no significant effect on body weight. The inotropic responsiveness to beta-adrenergic stimulation was diminished in papillary muscles from renal hypertensive rats: the maximum increase in the maximal rate of rise of tension produced by isoproterenol was 27.39 +/- 5.4 and 11.77 +/- 2.91 g X mm-2 X s-1 (P less than 0.05) in control and hypertensive animals, respectively. Similar results were obtained when the estimated maximal velocity of shortening of the contractile element (Vmax) was used to assess myocardial contractility. The inotropic response to CaCl2 was also significantly depressed in the 2-kidney, 1-clip rats. However, the relaxant and the chronotropic responses to isoproterenol were not significantly modified in the Goldblatt rats. Assays of beta-adrenergic receptors to l-[3H]dihydroalprenolol binding, showed no significant changes in the number (expressed per mg of membrane protein) or in the affinity of the beta-receptors. These results suggest that at an early stage of the renal hypertensive model the impaired inotropic response to isoproterenol is not mediated by an alteration of the beta-receptors and should be searched at a postreceptor adenyl cyclase level.
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PMID:Renal hypertension impairs inotropic isoproterenol effect without beta-receptor changes. 299 71

We have assessed the presence of VIP/PHI/secretin receptors in heart by: (1) testing the ability of the corresponding peptides to activate adenylate cyclase in cardiac membranes from rat, dog, Cynomolgus monkey and man, and (2) examining the ability of the same peptides to exert inotropic and chronotropic effects on heart preparations from rat and Cynomolgus monkey in vitro. Based on their affinity for natural peptides and synthetic analogs, two types of VIP/PHI/secretin receptors were characterized: the relatively nonspecific "secretin/VIP receptor" of rat heart (that is "secretin-preferring" only in that secretin was more efficient than VIP in stimulating adenylate cyclase), and the "VIP/PHI-preferring" receptor of man, monkey and dog heart. Four physiopathological situations affecting secretin/VIP receptors in rat heart were explored: In male rats from the Okamoto strain and the Lyon strain, two strains presenting spontaneous hypertension, heart membranes exhibited a markedly decreased response of adenylate cyclase to secretin/VIP, with lesser alterations in the responses to isoproterenol and glucagon. This impairment developed in parallel with the occurrence of hypertension and was reproduced in normotensive rats submitted to chronic isoproterenol treatment (but not in Goldblatt hypertensive rats). These findings are consistent with a hyperactivity of norepinephrine pathways in spontaneously hypertensive rats, leading to a reduced number of cardiac post-junctional secretin/VIP receptors bound to adenylate cyclase. Heart membranes from genetically obese (fa/fa) Zucker rats also exhibited severely decreased responses to secretin/VIP with lesser alterations in the responses to glucagon and isoproterenol. These anomalies were specific for the heart, and developed in concomitance with obesity. The first anomaly could not be corrected by severe food restriction. Secretin stimulation of heart adenylate cyclase was also selectively altered in streptozotocin-diabetic rats. Thus, two types of diabetic cardiomyopathy were characterized by a severe local alteration of secretin/VIP receptors coupled to adenylate cyclase. Hypothyroidism, provoked in rat by thyroidectomy or propylthiouracil treatment, again induced a marked decrease in secretin-stimulated cardiac adenylate cyclase activity. In rat papillary muscle electrically stimulated in vitro, secretin exerted a positive inotropic effect. This effect was reduced in obese (fa/fa) Zucker rats. In rat right atrium, secretin also exerted a positive chronotropic effects.(ABSTRACT TRUNCATED AT 400 WORDS)
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PMID:Heart receptors for VIP, PHI and secretin are able to activate adenylate cyclase and to mediate inotropic and chronotropic effects. Species variations and physiopathology. 608 34