Progression of myocardial abnormalities in experimental alcoholism

Abstract

To determine those characteristics of left ventricular functional and metabolic alterations in chronic ethanolism that may be time-dependent, up to 36 percent of total daily calories as ethanol was fed to dogs for an average of 18 months (study group 1) or 52 months (study group 2). The short- and long-term study groups were fed the same diet with vitamin supplements and were compared with simultaneously studied control animals. Left ventricular function was assessed in the intact anesthetized dogs using the thermodilution method for end-diastolic volume and stroke volume determinations. During preload increments with saline solution, a significantly greater increase in end-diastolic pressure was observed in both groups receiving ethanol as compared with the control animals; this increase was associated with reduced end-diastolic and stroke volume. However, the responses were similar in the short- and long-term study groups. Increased left ventricular collagen was the apparent basis for the compliance abnormality, but neither variable differed in the groups receiving ethanol. In contrast, the first derivative of ventricular pressure (dP/dt) normalized for preload and afterload, an index of left ventricular contractility, and the velocity of the contractile element (Vce) were significantly reduced only in the long-term study group while tissue calcium was normal. When chromium-51-EDTA was used as an extracellular marker, accumulation of water and sodium in myocardial cells was observed only in the long-term study group, without a reduction of cell potassium. In view of the dilatation of sarcoplasmic reticulum observed on electron microscopy, It is postulated that distortion of the tubular membranes may limit the rate of calcium availability to contractile protein and thus diminish contractile function in chronic alcoholism.