Intracellular calcium stores in chick cerebellum purkinje neurons:
ontogenetic and functional studies.
Sacchetto, Roberta, Kenneth D. Cliffer, Paola Podini, Antonello Villa,
Burgess N. Christensen, and Pompeo Volpe.
Centro di Studio per la Biologia e la Fisiopatologia Muscolare del
CNR, Dipartimento di Scienze Biomediche Sperimentali
dell'Universit[grave]a di Padova, 35121 Padova, Dipartimento di
Farmacologia dell'Universit[grave]a di Milano, Dibit Istituto
Scientifico San Raffaele, 20132 Milano, Istituto Pluridisciplinare di
Patologia Generale dell'Universit[grave]a di Messina, 98100 Messina,
Italy, and Department of Physiology and Biophysics, UTMB, Galveston,
77555 Texas, USA
APStracts 2:0188C, 1995.
Molecular composition of intracellular Ca2+ stores in developing
chicken cerebellum Purkinje neurons, from embryonic day 11 to
posthatching day 2, was studied by immunocytochemistry using specific
antibodies for three molecular constituents, the receptor(R)/channel
sensitive to inositol 1,4,5-trisphosphate (IP3), Ca2+-ATPase, and
calsequestrin (CS). CS, IP3R and Ca2+-ATPase were first detected, by
light microscopy immunofluorescence, in migrating Purkinje cells at
E11-E12 and throughout late phases of embryonic development.
Ontogenesis of CS, IP3R, and Ca2+-ATPase accompanied well defined
stages of cerebellum histogenesis and cytogenesis and was
accomplished before hatching. High-resolution immunogold
electronmicroscopy revealed that at E18-P1 CS was still largely
distributed to the endoplasmic reticulum (ER) lumen and began to be
segregated to ER subcompartments (calciosomes) only by P2, whereas
the IP3R was concentrated into ER cisternal stacks as early as E18.
Both ionotropic and metabotropic plasma membrane receptors were
present in dissociated, single chicken Purkinje cells from E16
onward, as indicated by measurements of membrane currents (whole-cell
recording mode) and of cytoplasmic Ca2+ transients, monitored with
the cell-trappable fluorescent indicator fura-2 AM, respectively.
Cytoplasmic Ca2+ transients were detected following either activation
of glutamate metabotropic receptors, i.e., evidence of IP3-sensitive
Ca2+ channels, or application of caffeine, i.e., evidence of
ryanodine-sensitive Ca2+ channels. Intracellular Ca2+ stores appear
to be functional during embryonic development.
Received 5 December 1994; accepted in final form 19 April 1995.
APS Manuscript Number C706-4.
Article publication pending Am. J. Physiol. (Cell Physiology).
ISSN 1080-4757 Copyright 1995 The American Physiological Society.
Published in APStracts on 16 May 1995.