کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
---|---|---|---|---|
1936693 | 1050700 | 2008 | 7 صفحه PDF | دانلود رایگان |
The view that Ca2+ entry through voltage-dependent Ca2+ channels (VDCC) and through nicotinic receptors for acetylcholine (nAChRs) causes equal catecholamine release responses in chromaffin cells, was reinvestigated here using new protocols. We have made two-step experiments consisting in an ACh prepulse followed by a depolarizing pulse (DP). In voltage-clamped bovine chromaffin cells an ACh prepulse caused a slow-rate release but augmented 4.5-fold the much faster exocytotic response triggered by a subsequent depolarizing pulse (measured with capacitance and amperometry). If the ACh prepulse was given with mecamylamine or in low external Ca2+, the secretion increase disappeared. This suggests a two-step model for the effects of ACh: (1) meager Ca2+ entry through nAChRs mostly serves to keep loaded with vesicles the secretory machine; and (2) in this manner, the cell is prepared to respond with an explosive secretion of catecholamine upon depolarization and fast high Ca2+ entry through VDCC.
Journal: Biochemical and Biophysical Research Communications - Volume 365, Issue 3, 18 January 2008, Pages 413–419