title: Effect of enalapril on the inotropic response to isoproterenol in renal hypertensive rats.
abstract: It is not clear whether regression of cardiac hypertrophy normalizes cardiac contractility. We studied the effect of enalapril treatment on the contractile response to beta-adrenergic stimulation with isoproterenol in renal hypertension. Male Wistar rats (n = 28) were divided into a clipped group (n = 14) and control group (n = 14). Three weeks after surgery, half of the animals from each group received for 21 days either enalapril (2.5 mg/kg) twice a day or vehicle by gastric intubation. Arterial pressure and body weight were measured twice a week. At the end of the experimental period, the hearts were excised, the ventricles were weighed, and the left ventricular papillary muscle was mounted in a bath. Myocardial contractility was characterized by the maximal developed tension, the maximal rate of rise of tension (+T), and the maximal velocity of relaxation (-T), which were measured at basal conditions and after cumulative doses of isoproterenol (10(-11) to 10(-4) M). The ratio of ventricular weight to body weight increased in hypertensive rats. Enalapril induced a decrease in arterial pressure and in the cardiac mass in both treated groups (p less than 0.05). The basal values of maximal developed tension, +T, and -T were similar in the four groups. The increment in +T and -T in response to isoproterenol (10(-4) M) was depressed in the hypertensive animals and in both treated groups (p less than 0.05). There was no significant difference in the +T/-T ratio or in the ED50 among the groups.(ABSTRACT TRUNCATED AT 250 WORDS)
authors.affiliation: Instituto de Investigaciones Cardiologicas, Facultad de Medicina, Universidad de Buenos Aires, Argentina.
authors.forename: H
authors.initials: H
authors.lastname: Gómez Llambí
authors.forename: A
authors.initials: A
authors.lastname: Mazzadi
authors.forename: M
authors.initials: M
authors.lastname: Fontán
authors.forename: C M
authors.initials: CM
authors.lastname: Taquini
mesh_terms: D000818:Animals; D001835:Body Weight / Q000187:drug effects; D006332:Cardiomegaly / Q000188:drug therapy; D004656:Enalapril / Q000627:therapeutic use*; D006978:Hypertension, Renovascular / Q000188:drug therapy*; D007545:Isoproterenol / Q000494:pharmacology; D008297:Male; D009126:Muscle Relaxation / Q000187:drug effects; D009200:Myocardial Contraction / Q000187:drug effects; D010210:Papillary Muscles / Q000502:physiology; D051381:Rats; D011919:Rats, Inbred Strains
chemical_list: D004656:Enalapril; D007545:Isoproterenol