Somatostatin inhibits two types of voltage-activated calcium currents in rat growth-hormone secreting cells.

Somatostatin is known as the hypothalamic inhibitor of growth-hormone (GH) secretion from the pituitary gland. The present study examines the effects of somatostatin on voltage-gated calcium currents recorded from enriched populations of normal GH-secreting cells (somatotrophs). Two types of voltage-activated calcium currents were recorded from somatotrophs with the whole-cell mode of the patch-clamp technique. Somatostatin exerted a reversible blocking effect on these two types of calcium currents. These findings suggest that somatostatin can regulate intracellular calcium in somatotrophs by a direct control of calcium fluxes across the plasma membrane of these cells, thereby affecting the level of GH secretion.