Effect of glucose on endothelin-1-induced calcium transients in cultured bovine retinal pericytes

Published work has shown that endothelin-l-induced contractility of bovine retinal pericytes is reduced after culture in high concentrations of glucos e. The purpose of the present study was to establish the profile of endothe lin-l-induced calcium transients in pericytes and to identify changes occur ring after culture in high concentrations of glucose. Glucose had no effect on basal levels of cytosolic calcium or on endothelin-l-induced calcium re lease from intracellular stores. However, influx of calcium from the extrac ellular medium after endothelin-l stimulation was reduced in pericytes that had been cultured in 25 mM D-glucose. L-type Ca2+ currents were identified by patch clamping. The L-type Ca2+ channel agonist, (-)-Bay K8644, caused less influx of calcium from the extracellular medium in pericytes that had been cultured in 25 mM D-glucose than in those cultured with 5 mM D-glucose . However, 3-O-methylglucose, a nonmetabolizable analogue of glucose which can cause glycation, had similar effects to those of high concentrations of glucose. The results suggest that reduced function of the L-type Ca2+ chan nel that occurs in bovine retinal pericytes after culture in high concentra tions of D-glucose is probably due to glycation of a channel protein.