title: Influence of insulin treatment on the mechanical properties and inotropic response to ethanol in diabetic myocardium.
abstract: Diabetes significantly affects cardiac performance, as does ethanol. To assess whether insulin treatment alters the inotropic response to acute ethanol exposure and reverses diabetes-induced myocardial dysfunction, male Wistar rats were made diabetic using streptozocin, 55 mg/kg intravenously. The inotropic effect of ethanol on normal, diabetic, and insulin-treated (8 weeks) diabetic animals was studied using isolated, left-ventricular papillary muscle preparations superfused with Tyrode's solution under isometric conditions. Peak tension developed, time to peak tension (TPT), time to 90% relaxation (RT90), maximum rate of tension developed (+VT), and maximum rate of fall in tension (-VT) were determined in the absence and presence of clinically relevant concentrations of ethanol for 10 minutes. In insulin-treated diabetic muscles, baseline developed tension, +VT, and -VT were enhanced, and the prolongation of TPT and RT90, characteristic of diabetic myocardium, was attenuated. The magnitude of the reduction in developed tension in response to ethanol, 80 mg/dL, was slightly greater in untreated diabetic myocardium. Higher concentrations of ethanol (120 to 240 mg/dL) decreased tension in all groups and was of similar magnitude. The negative inotropic effect of higher ethanol concentrations was associated with shortening of TPT and RT90, as well as a diminution of +VT and -VT. It is concluded that with insulin treatment, the mechanical properties of diabetic myocardium are normalized; however, neither the myocardium's sensitivity to ethanol nor the overall magnitude of ethanol's negative inotropic effect is modified by insulin treatment.
authors.affiliation: Department of Physiology, Wayne State University School of Medicine, Detroit, Michigan, USA.
authors.forename: R A
authors.initials: RA
authors.lastname: Brown
authors.forename: A
authors.initials: A
authors.lastname: Adams
authors.forename: A O
authors.initials: AO
authors.lastname: Savage
mesh_terms: D000818:Animals; D003921:Diabetes Mellitus, Experimental / Q000628:therapy*; D003925:Diabetic Angiopathies / Q000628:therapy*; D000431:Ethanol / Q000494:pharmacology*; D007328:Insulin / Q000494:pharmacology* / Q000627:therapeutic use; D008297:Male; D009200:Myocardial Contraction / Q000187:drug effects* / Q000502:physiology; D051381:Rats; D017208:Rats, Wistar
chemical_list: D007328:Insulin; D000431:Ethanol