Increase in catecholamine release and 45Ca2+ uptake induced by GABA in cultured bovine adrenal chromaffin cells.

The role of Ca2+ in GABA-evoked catecholamine (CA) release from adrenal medulla was investigated in primary cultures of bovine adrenal chromaffin cells. GABA facilitated the 45Ca2+ uptake associated with the increase of Ca release in cultured bovine adrenal chromaffin cells. The effects of GABA on both 45Ca2+ uptake and CA release were blocked by bicuculline and picrotoxin. Nifedipine reduced the 45Ca2+ uptake and CA release induced by GABA. These data support our previous suggestion that the activation of GABA receptors on adrenal chromaffin cells facilitates the Ca2+ influx through voltage-sensitive Ca2+ channels, leading to the release of CA.