AJP - Heart and Circulatory Physiology, Vol 250, Issue 1 108-H113, Copyright © 1986 by American Physiological Society
Reversibility of diabetic cardiomyopathy with insulin in rabbits
F. S. Fein, B. Miller-Green, B. Zola and E. H. Sonnenblick
Diabetes mellitus causes a cardiomyopathy in human subjects, independent of
atherosclerotic coronary artery disease. Ventricular papillary muscle
function studies in chronically diabetic rats and rabbits have shown
diminished contractility and a prolonged duration of contraction. In rats
there was complete reversibility of these changes with insulin therapy.
However, the effects of insulin on the myocardial mechanics of diabetic
rabbits have not been studied. Therefore, rabbits diabetic for 3-4 mo
(after alloxan injection) were treated with PZI insulin for 3-4 mo, and the
mechanical performance of their right ventricular papillary muscles was
compared with that of untreated diabetic animals and age-matched controls.
Insulin therapy normalized serum glucose concentration. All abnormalities
in papillary muscle function were completely reversed in insulin-treated
animals. Norepinephrine (NE) dose responses were also evaluated in muscles
from all groups. There were no differences in the positive inotropic
effects of NE between groups. However, the data suggested, in diabetic
animals a blunted response of peak relaxation rate to NE; this abnormality
was reversed in muscles from treated animals. These findings indicate that
previous work on diabetic rats can be extended to diabetic rabbits and
suggest that chronic insulin therapy completely reverses the contractile
alterations in hearts from these diabetic animals.
