1. The possible role of intracellular @entity141 levels ([ @entity141 ]i) in desensitization of nicotinic @entity934 receptors (AChRs) was investigated in @entity35 cultured chromaffin cells by use of combined whole-cell patch clamping and confocal laser scanning microscopy with the fluorescent dye @entity3576 . 2. On cells held at -70 mV, pressure-application of @entity1239 elicited inward currents with associated [ @entity141 ]i rises mainly due to influx through nicotinic AChRs. These responses were blocked by @entity2899 (10 microM) but were insensitive to alpha-bungarotoxin (1 microM) or @entity3280 (0.1 mM). 3. Pressure applications of 1 mM @entity1239 for 2 s (conditioning pulse) evoked inward currents which faded biexponentially to a steady state level due to receptor desensitization and were accompanied by a sustained increase in [ @entity141 ]i. Inward currents evoked by subsequent application of brief test pulses of @entity1239 were @entity308 but recovered with a time course reciprocal to the decay of the [ @entity141 ]i transient induced by the conditioning pulse. 4. Omission of intracellular @entity141 chelators or use of high extracellular @entity141 solution (10 mM) lengthened recovery of nicotinic AChRs from desensitization while adding @entity18650 or @entity4527 intracellularly had the opposite effect. When the patch pipette contained @entity3576 or no chelators, after establishing whole cell conditions the rate of recovery became progressively longer presumably due to dialysis of endogenous @entity141 buffers. None of these manipulations of external or internal @entity141 had any effect on onset or steady state level of desensitization. 5. High spatial resolution imaging of [ @entity141 ]i in intact cells (in the presence of 0.1 mM @entity3280 ) showed that its level in the immediate submembrane area decayed at the same rate as in the rest of the cell, indicating that @entity141 was in a strategic location to modulate (directly or indirectly) AChR desensitization. 6. The present data suggest that desensitized nicotinic AChRs are stabilized in their conformation by raised [ @entity141 ]i and that this @entity1032 their recovery to full activity.

Imaging of intracellular calcium during desensitization of nicotinic @entity934 receptors of XXXX chromaffin cells.

@entity1032 :: ('MESH:D008607', 'Disease') :: ['phenomenon retards'] @entity308 :: ('MESH:D003866', 'Disease') :: ['depressed'] @entity35 :: ('10116', 'Species') :: ['rat'] @entity3280 :: ('CHEBI:48775', 'Chemical') :: ['Cd2+'] @entity4527 :: ('MESH:D004533', 'Chemical') :: ['EGTA'] @entity1239 :: ('MESH:D009538', 'Chemical') :: ['nicotine'] @entity3576 :: ('MESH:C059715', 'Chemical') :: ['fluo-3'] @entity18650 :: ('MESH:C025603', 'Chemical') :: ['BAPTA'] @entity141 :: ('CHEBI:29108', 'Chemical') :: ['Ca2+'] @entity2899 :: ('MESH:D014403', 'Chemical') :: ['(+)-tubocurarine'] @entity934 :: ('MESH:D000109', 'Chemical') :: ['acetylcholine']
@entity35 :: (10116,Species) :: ['rat']
