CARDIAC CONTRACTILE ACTIVITY AND ACTION-POTENTIAL IN SPONTANEOUSLY DIABETIC BB RATS

Experimental studies concerning the effects of diabetes on cardiac fun ction have been carried out mainly in chemically induced diabetic rat models. Nevertheless, the relevance of such animal models to human dia betic cardiomyopathy is somewhat uncertain. The Bio-Breeding (BE) rat develops a syndrom similar to human insulin-dependent diabetes mellitu s. Therefore we investigated the effects of diabetes on the action pot ential (AP) and on the contractile activity of right papillary muscles isolated from spontaneously diabetic BE rat hearts. Diabetic papillar y muscles exhibited an increased time to peak shortening and a delayed relaxation. The membrane resting potential and the AP amplitude were not significantly affected by diabetes whereas the AP repolarization p hase was lengthened. These preliminary results show that in spontaneou sly diabetic BE rats, the alterations in mechanical performance and in electrophysiological properties are close to those previously observe d in chemically induced diabetic rats.