Voltage-operated calcium channel heterogeneity in pancreatic beta cells: physiopathological implications.

Voltage-operated calcium channels play crucial roles in stimulus-secretion coupling in pancreatic beta cells. A growing body of evidence indicates that these channels in beta cells are heterogeneous. In particular, not all the high-threshold calcium channels expressed belong to the best known L-type. In rat insulinoma cells, for example, L, N, and P/Q-type channels are present, while in human beta cells L-type and P/Q-type dominate. Where present, N-type and P/Q-type channels participate, alongside with the dominant L-type, in the control of sugar- or depolarization-induced hormone release. Distinct biophysical properties and selective modulation of the channel subtypes are likely to play important physiological roles. T-type channels are involved in beta cell apoptosis, while calcium channel autoantibodies recognizing high-threshold channels in beta cells, have been described both in neurological and diabetic patients. Subtype-selective calcium channel drugs have the potential for being beneficial in beta cell pathological states.