Adrenoceptor-linked [45Ca2+] uptake in platelets from diabetic rats: a model for human platelets.

Adrenoceptor-linked 45 calcium uptake was investigated in platelet from diabetic rats (hyperglycaemic, streptozotocin-induced, of 60 days duration). Basal uptake was markedly enhanced in platelets from diabetic rats compared with controls. However, whereas adrenaline-stimulated uptake was unchanged, isoprenaline-stimulated uptake was significantly reduced and noradrenaline-stimulated uptake significantly increased. These latter data indicate that there are differential alterations of adrenoceptor subtypes in diabetes (i.e. an increase in alpha- but decrease in beta-adrenoceptors). These changes in calcium uptake and in adrenoceptor activity may relate to altered platelet function known to occur in experimental diabetes. Furthermore, the similarity of the rat platelet with that of the human (in terms of absolute calcium uptake, responses to agonists and changes in diabetes), renders the rat platelet an appropriate model for studying calcium dynamics and linked adrenoceptors in diabetes.