An androgenic steroid decreases left ventricular compliance in rats

Abstract

The effect of chronic administration of an androgenic steroid on left ventricular (LV) compliance and contractility was studied in rats. Rats received a biweekly intramuscular injection of nandrolone decanoate (5 mg/kg; steroid group) or the vehicle (control group) for 3 mo. Cardiac performance was measured in anesthetized open-chest ventilated rats. LV compliance was determined from the slope of the LV end-diastolic pressure (LVEDP) vs. LV end-diastolic (LVED) strain relation measured in the long and short axes of the LV. LV regional myocardial compliance was determined from the slope of the LVED stress vs. LVED strain relation (myocardial elastic stiffness constant). Cardiac contractility was determined from the slope of the LV end-systolic (LVES) pressure vs. LVES strain relation. Systolic performance was also assessed from the slope of the pressure-length area (PL area) or stroke work vs. LVED strain and LVEDP relations. Nandrolone decanoate decreased body weight, heart weight, and plasma testosterone concentrations but increased the heart weight-to-body weight ratio. Nandrolone decanoate decreased LV compliance (slope of LVEDP vs. LVED strain relation in long and short axes; steroid vs. control, P < 0.01). This occurred as a result of an increased regional myocardial stiffness (myocardial elastic stiffness constant; steroid vs. control, P < 0.01), which resulted in a reduced cardiac systolic performance (PL area vs. LVEDP, slope of steroid vs. control group, P < 0.005). Diastolic geometry (LV wall thickness-to-radius ratio) and cardiac contractility were unchanged with steroid administration. In conclusion, chronic administration of the androgenic steroid nandrolone decanoate decreases LV myocardial compliance and thus overall cardiac performance without altering contractility in rats.