Pharmacological study of isoproterenol and diabetic cardiomyopathies in rat right ventricular strips.
The present study was undertaken to compare the cardiomyopathies induced by experimental diabetes mellitus and chronic isoproterenol (ISO) pretreatment on inotropic reactivity of right ventricular strips from rats. One month after initiation of treatment, cardiac muscle was isolated and challenged with either the beta-adrenoceptor agonist ISO or the calcium channel activator Bay K 8644. Sensitivity and responsiveness to these agonists were determined. Crude membrane preparations were obtained from residual ventricular muscle and beta-adrenoceptor density determined using iodocyanopindolol. Isolated right ventricular strips from diabetic and ISO-treated rats demonstrated hyperresponsiveness to the inotropic effects of Bay K 8644 but subsensitivity to ISO. Ventricular beta-adrenoceptor density was found to be significantly depressed in membrane preparations from both diabetic and ISO-treated groups relative to controls. These data indicate that both forms of cardiomyopathy may affect inotropic reactivity through similar alterations to beta-adrenoceptors and calcium utilization.
Gunasekaran
S
S
Department of Pharmacology, Texas Tech University Health Sciences Center, Lubbock 79430.
Young
J A
JA
Tenner
T E
TE
D001498:3-Pyridinecarboxylic acid, 1,4-dihydro-2,6-dimethyl-5-nitro-4-(2-(trifluoromethyl)phenyl)-, Methyl ester / Q000494:pharmacology*; D000318:Adrenergic beta-Agonists / Q000494:pharmacology*; D000818:Animals; D009202:Cardiomyopathies / Q000209:etiology / Q000503:physiopathology*; D003921:Diabetes Mellitus, Experimental / Q000150:complications*; D006352:Heart Ventricles / Q000187:drug effects; D066298:In Vitro Techniques; D007545:Isoproterenol / Q000494:pharmacology*; D008297:Male; D009200:Myocardial Contraction / Q000187:drug effects; D051381:Rats; D017207:Rats, Sprague-Dawley
D000318:Adrenergic beta-Agonists; D001498:3-Pyridinecarboxylic acid, 1,4-dihydro-2,6-dimethyl-5-nitro-4-(2-(trifluoromethyl)phenyl)-, Methyl ester; D007545:Isoproterenol