NEUROPEPTIDE-Y INHIBITS NICOTINIC CHOLINERGIC CURRENTS BUT NOT VOLTAGE-DEPENDENT CALCIUM CURRENTS IN BOVINE CHROMAFFIN CELLS

The effects of neuropeptide Y (NPY; 1-36) and NPY fragment (16-36) on nicotinic currents (I(ACh)) and voltage-dependent calcium currents (I(Ca)) were studied in bovine chromaffin cells using the whole-cell patch-clamp technique. The peak amplitude of inward nicotinic currents was markedly depressed by both NPY (1-36) and NPY (16-36). In contrast, I(Ca) was unaffected by either NPY (1-36) or NPY (16-36). Both pertussis toxin pretreatment and including GDP [beta-S] in the patch pipette solution completely abolished the inhibitory effect of NPY on I(ACh). It is concluded that inhibition of I(ACh) probably represents the mechanism by which NPY decreases catecholamine release from adrenal medulla. This effect appears to be mediated by a G-protein-coupled Y2 receptor.