The influence of gender, diabetes, and acetaldehyde on the intrinsic contractile properties of isolated rat myocardium.

Abstract

Diabetes is associated with ventricular dysfunction. Ethanol consumption increases the risk of cardiovascular disease among diabetics. Acetaldehyde (ACA), the main ethanol metabolite, depresses cardiac contraction and contributes to ethanol-induced cardiac dysfunction. This study examined the influence of gender and diabetes on ACA-induced myocardial dysfunction. Adult male and female rats were made diabetic with streptozotocin (55 mg/kg). Left ventricular papillary muscles were isolated and stimulated to contract at 0.5 Hz. The mechanical parameters measured were peak tension development, time-to-peak tension (TPT), time-to-90% relaxation (RT90), and maximum velocities of tension development and decline (+/-VT). TPT and RT90 were comparably similar between genders. The +/-VT appeared to be slower in myocardium from female rats when compared to that of male counterparts, although the difference was not significant. Experimental diabetes elicited severe hyperglycemia, cardiac hypertrophy, hepatomegaly, and renal hypertrophy in both male and female animals. Myocardial mechanical properties exhibited prolonged TPT and RT90 in diabetic myocardium from both genders. The +/-VT was significantly reduced by diabetes in male but not in female myocardium. Acute ACA exposure decreased myocardial tension development and the +/-VT and shortened TPT and RT90 in myocardium from normal and diabetic rats of both genders. The ACA-induced depressant response on tension development was slightly enhanced by the diabetic state. In conclusion, these data suggest that the development of diabetes-induced myocardial dysfunction is similar between male and female animals and that the ACA-induced myocardial depressant action may be affected by diabetes but not by gender.