PURIFIED MONILIFORMIN DOES NOT AFFECT THE FORCE OR RATE OF CONTRACTION OF ISOLATED GUINEA-PIG ATRIA

Chronic exposure to moniliformin results in the development of myocard ial hypertrophy and degeneration. The cause of this hypertrophy is unk nown. However, moniliformin-induced hypoxia or altered function of car diac pyruvate dehydrogenase, rather than direct cardiostimulation have been proposed as potential mechanisms. Isolated guineapig atria were used in a cumulative concentration-response model to evaluate the dire ct effect of moniliformin on the rate and force of atrial contraction. Moniliformin did not affect the rate or force of atrial contraction. These results are consistent with the hypothesis that moniliformin doe s not have a cardiostimulatory effect. Therefore cardiac stimulation, e.g. stimulation of beta-adrenergic receptors, is unlikely to be the c ause of the myocardial hypertrophy observed in poultry chronically int oxicated with moniliformin.