Calcium/Calpain mediated regulation of cyclic nucleotide phosphodiesterases, PDE3A and PDE5, in human platelets

Background Calpain, intracellular non-lysosomal calcium-dependent proteinase, is activated by a number of signaling pathways that lead to the elevation of intraplatelet calcium concentrations. Physiological roles of calpain, highly expressed in platelets, include regulation of platelet aggregation and adhesion, while excessive activation of calpain in such pathological disorders as diabetes could cause changes in platelet functions, resulting in platelet hyperactivation. Platelets from diabetic patients are also characterized by resistance to nitric oxide inhibition. Here we examined if calpain could regulate major cAMP and cGMP hydrolyzing phosphodiesterases (PDEs), PDE3A and PDE5, in human platelets.