CALMODULIN CONTENT AND IN-VITRO CONTRACTILITY OF DUODENUM FROM STREPTOZOTOCIN-INDUCED DIABETIC RATS - EFFECTS OF INSULIN THERAPY AND CALMODULIN ANTAGONISM

The effects of experimental diabetes and insulin treatment on the decr eased reactivity of isolated rat duodenum to KCI and calmidazolium, a specific calmodulin antagonist, were examined. After 8 weeks of strept ozotocin diabetes, the contractile effect of KCI and the non-competiti ve antagonistic effect of calmidazolium against KCI on isolated rat du odenum were decreased. Calmodulin levels, as measured by radioimmunoas say, were also found to be decreased in duodenum from streptozotocin-d iabetic rats. Neither impaired reactivity to KCI nor decreased calmodu lin levels in diabetic rat duodenum were corrected by treatment with i nsulin (10 IU/kg for 20 days). Following insulin treatment, there was only a partial correction in the antagonistic effect of calmidazolium as shown by the increase in non-competitive antagonist affinity consta nt.