A ROLE FOR PROTEIN-KINASE-C IN THE ATTENUATED RESPONSE TO 5-HYDROXYTRYPTAMINE IN AORTAS FROM STREPTOZOTOCIN-DIABETIC RATS

We investigated protein kinase C participation in the contractile resp onse to 5-hydroxytryptamine (5-HT), and in the interaction between 5-H T and endothelin-1, in aortas from control and diabetic rats. Diabetic rats display attenuated reactivity to 5-HT (i.e., approximately 47% o f control maximum). The protein kinase C inhibitor calphostin C (1 mu M) significantly reduced responses to 5-HT only in aortas from control rats. In diabetic rats, maximum responses to 5-HT, in the presence of endothelin-1 (3 nM), were not significantly different to controls. Th e additional presence of calphostin C significantly reduced responses only in aortas from diabetic rats. These results may indicate an abnor mality in the protein kinase C second messenger system during diabetes . (C) 1997 Elsevier Science B.V.