Voltage-Gated Calcium Channels and Tenocyte Response to Oxidative Stress

Abstract

Voltage-gated channels are important for excitable cells, such as neurons or muscle cells. Surprisingly, they have been described, at the gene expression and protein levels, in nonexcitable cells such as bone, kidney, and tendons. Their function is largely unknown, but the Abreu lab has found significant gene expression for these channels, specifically dihydropyridine receptor, in the tenocytes of aged mice compared to young animals. This suggests that dihydropyridine receptor (DHPR) are not only expressed in tenocytes, but expression decreases with age. To investigate the role of DHPR in tenocyte function, cells are exposed to oxidative stress by hydrogen peroxide to examine effects of an inhibitor and agonist of the channel. Cell samples were cultured in Nifedipine (calcium channel inhibitor) or Bay K 8644 (calcium channel agonist), then exposed to hydrogen peroxide at varying doses. Oxidation in each group induced either apoptosis or necrosis. When necrosis is induced, results suggested that increased DHPR sensitivity provides a protective effect to cells. When apoptosis is induced, these data suggest that DHPR doesn’t play a major role in helping tenocytes respond.