Caffeine- and ryanodine- sensitive calcium stores in cultured
guinea pig myenteric neurons.
Kimball, Beth C., David I. Yule, Michael W. Mulholland.
Departments of Surgery and Physiology, University of Michigan, Ann
Arbor, Michigan, 48109
APStracts 2:0232G, 1995.
In single fura-2-loaded myenteric neurons, caffeine caused
concentration- dependent increases in intracellular calcium ([Ca2+]i)
that were quantal, saturable, and reversible. Inhibition of caffeine
-induced calcium release was demonstrated by ryanodine (1 mM),
dantrolene (10 mM) and procaine (5 mM). Caffeine and cyclopiazonic
acid (30 mM) released overlapping calcium stores, while the caffeine
-releaseable pool was a subset of Ca2+ released by the calcium
ionophore ionomycin (4 mM). Both mild depolarization (KCl 7.5 mM) and
a submaximal concentration of caffeine (1 mM) produced neuronal
[Ca2+]i oscillations in one third of cells examined, which could be
abolished by ryanodine (1 mM) or removal of extracellular calcium.
Release of caffeine- sensitive calcium stores induced influx of
extracellular calcium. Immunolocalization using confocal microscopy
revealed ryanodine receptor- like staining within the cytosol of
cultured myenteric neurons.
Received 29 June 1995; accepted in final form 18 October 1995.
APS Manuscript Number G279-5.
Article publication pending Am. J. Physiol. (Gastrointest. Liver
Physiology).
ISSN 1080-4757 Copyright 1995 The American Physiological Society.
Published in APStracts on 30 November 95