ATTENUATED CONTRACTILE RESPONSE OF DIABETIC RAT AORTA TO CAFFEINE BUTNOT TO NORADRENALINE IN CA2-FREE MEDIUM()

The phasic contractions induced by noradrenaline and caffeine were com pared in aortic rings from rats with 8-12 week streptozotocin-induced diabetes and age-matched control rats. In Ca2+-free medium, no differe nce was found in the magnitude of the contractile responses to 10 mu M noradrenaline between control and diabetic aortas. The transient cont raction induced by 20 mM caffeine was significantly diminished in diab etic aorta compared to control aorta. The results suggest that the abi lity of caffeine, but not of inositol 1,4,5-trisphosphate, to mobilize Ca2+ from intracellular stores is impaired in diabetic rat aorta.