Influence of Glucocorticoids on Cholinergic Stimulation-Induced Catecholamine Secretion from the Rat Adrenal Medulla
Influence of Glucocorticoids on Cholinergic Stimulation-Induced Catecholamine Secretion from the Rat Adrenal Medulla
- Dong-Yoon Lim Jae-Joon Lee Oh-Seong Gweon
- 대한생리학회-대한약리학회
- The Korean Journal of Physiology & Pharmacology
- 제2권 제2호
- 등재여부 : KCI등재
- 1998.01
- 173 - 184 (12 pages)
<P> The present study was undertaken to examine the influence of glucocorticoids on the secretory responses of catecholamines (CA) evoked by acetylcholine (ACh), DMPP, McN-A-343, excess K<SUP>+</SUP> and Bay-K-8644 from the isolated perfused rat adrenal gland and to clarify the mechanism of its action. The perfusion of the synthetic glucocorticoid dexamethasone (10-100 ՌM) into an adrenal vein for 20 min produced a dose-dependent inhibition in CA secretion evoked by ACh (5.32 mM), excess K<SUP>+ </SUP>(a membrane-depolarizor 56 mM), DMPP (a selective nicotinic receptor agonist, 100 ՌM for 2 min), McN-A-343 (a muscarinic receptor agonist, 100 ՌM for 4 min), Bay-K-8644 (a calcium channel activator, 10 ՌM for 4 min) and cyclopiazonic acid (a releaser of intracellular Ca<SUP>2+</SUP>, 10 ՌM for 4 min). Similarly, the preperfusion of hydrocortisone (30 ՌM) for 20 min also attenuated significantly the secretory responses of CA evoked by nicotinic and muscarinic receptor stimulation as well as membrane-depolarization, Ca<SUP>2+</SUP> channel activation and the release of intracellular Ca<SUP>2+</SUP>. Furthermore, even in the presence of betamethasone (30ՌM), CA secretion evoked by ACh, excess K<SUP>+</SUP>, DMPP and McN-A-343 was also markedly inhibited. Taken together, the present results suggest that glucocorticoids cause the marked inhibition of CA secretion evoked by both cholinergic nicotinic and muscarinic receptor stimulation from the isolated perfused rat adrenal gland, indicating strongly that this inhibitory effect may be mediated by inhibiting influx of extracellular calcium as well as the release of intracellular calcium in the rat adrenomedullary chromaffin cells.