Catecholamines in turkeys with inbred cardiomyopathy

Patients with heart failure often have increased adrenergic nervous system activity. However, since the role of catecholamines in the development of inherited dilated cardiomyopathy is not totally clear, this study was designed to examine catecholamines in turkeys with inbred dilated cardiomyopathy (DCM). Plasma and tissue (heart, aorta, and kidney) catecholamines were measured in DCM and normal turkeys at ages 1, 10, 30, and 60 days, with echocardiograms and intra-arterial pressure obtained at 60 days. DCM turkeys weighed less than controls at all ages. At 60 days, cardiac dysfunction was evident by hypotension, cardiac dilatation, and decreased shortening fraction. Unlike other models of heart failure, cardiac norepinephrine was not depleted in DCM birds, and in fact was higher than controls at ages 10 and 30 days. Kidney norepinephrine was also equal to or greater than control birds, and both cardiac and kidney dopamine were present in normally low concentrations. In 60 day old DCM birds, reduced shortening fraction correlated with lower mean arterial pressure (r = 0.77, P < 0.001), but heart rate remained constant. The relatively high cardiac norepinephrine in the hearts of DCM turkeys suggests that the sympathetic nervous system may play a uniquely different pathophysiologic role in this disorder compared to heart failure of other etiologies.