Crosstalk Between Calcium and cAMP in Pancreatic Alpha Cells

Abstract

10 days after EC. Resting intracellular Ca 2þ concentration ([Ca 2þ ] rest ) was measured in vivo using Ca 2þ selective microelectrodes on days 0, 2, 4, 6, 8, and 10 after EC. In group A the average [Ca 2þ ] rest was 1113.8 nM on day 0 and did not change on subsequent days. On days 0, 2, 4, 6, 8 and 10 [Ca 2þ ] rest (in nM) in polarized-exercised muscle fibers in group B was 395538, 381535, 334523, 295539, 268527, and 223527. In group C (ECþpGz) [Ca 2þ ] rest was 402546, 304526, 260535, 145516, 121510 nM and 11356, showing a significant difference from group B by day 2 and reached control by day 10. In group D (ECþpGzþLNAME) the beneficial effect of pGz on [Ca 2þ ] rest was abolished. We conclude that EC induced a chronic elevation of [Ca 2þ ] rest in skeletal muscle that lasted up to 10 days and that pGz was able to accelerate the return to normal [Ca 2þ ] homeostasis following EC induced muscle injury. The salutary effect of pGz on [Ca 2þ ] rest appears to be mediated by an increase in NO generation, since the NOS blocker, L-NAME, eliminated the effect of pGz on [Ca 2þ ] rest after EC.