Stimulatory action of gamma-aminobutyric acid on catecholamine secretion from bovine adrenal chromaffin cells measured by a real-time monitoring system.
The present study was designed to evaluate the role of gamma-aminobutyric acid (GABA) in the secretory function of cultured chromaffin cells using the method of real-time monitoring. GABA evoked the secretion of catecholamines (CA) from adrenal chromaffin cells in a dose-dependent manner. Bicuculline 10(-5) M inhibited the stimulatory action of GABA. Diazepam 5 X 10(-6) and 2.5 X 10(-5) M facilitated the secretory response evoked by 7 X 10(-5) M GABA by 22% and 96%, respectively, which was antagonized by Ro 15-1788. This finding suggests that GABA-benzodiazepine receptor coupling can function in the secretion of CA from the adrenal chromaffin cells in a manner similar to that observed in the brain. GABA-evoked release of CA was reduced by 1 microM nifedipine to 16% of control, suggesting the involvement of voltage-sensitive Ca2+ channels in the mechanisms of the CA-releasing action of GABA in these cells. From these findings, the involvement of GABAergic mechanisms in the regulation of adrenal medullary function can be proposed.
D000311:Adrenal Glands / Q000187:drug effects / Q000378:metabolism*; D000818:Animals; D002395:Catecholamines / Q000378:metabolism*; D002417:Cattle; D002838:Chromaffin System / Q000187:drug effects / Q000378:metabolism*; D003975:Diazepam / Q000494:pharmacology; D005442:Flumazenil / Q000494:pharmacology; D008274:Magnesium / Q000494:pharmacology; D009543:Nifedipine / Q000494:pharmacology; D005680:gamma-Aminobutyric Acid / Q000494:pharmacology*
D002395:Catecholamines; D005442:Flumazenil; D005680:gamma-Aminobutyric Acid; D008274:Magnesium; D009543:Nifedipine; D003975:Diazepam