Premium
Depolarisation‐evoked Ca 2+ waves in the non‐excitable rat megakaryocyte
Author(s) -
Thomas David,
Mason Michael J.,
MahautSmith Martyn P.
Publication year - 2001
Publication title -
the journal of physiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.802
H-Index - 240
eISSN - 1469-7793
pISSN - 0022-3751
DOI - 10.1111/j.1469-7793.2001.00371.x
Subject(s) - depolarization , biophysics , agonist , endoplasmic reticulum , intracellular , chemistry , membrane potential , medicine , endocrinology , receptor , microbiology and biotechnology , biology , biochemistry
1 A combination of patch clamp, confocal microscopy and immunohistochemistry was used to examine the spatial properties of Ca 2+ signalling in the rat megakaryocyte, a non‐excitable cell type in which membrane potential can markedly modulate agonist‐evoked Ca 2+ release. 2 Intracellular calcium ion concentration ([Ca 2+ ] i ) increases, stimulated by both ADP and depolarisation, frequently originated from a peripheral locus and spread as a wave throughout the cell. Spatially restricted [Ca 2+ ] i increases, consistent with elementary Ca 2+ release events, were occasionally observed prior to ADP‐evoked waves. 3 ADP‐ and depolarisation‐evoked Ca 2+ waves travelled approximately twice as fast around the periphery of the cell compared to across its radius, leading to a curvilinear wavefront. There was no sigificant difference between wave velocities generated by the two stimuli. 4 Immunohistochemical staining of type III IP 3 receptors, the endoplasmic reticulum‐specific protein GRP78/BiP and calreticulin indicated a major peripheral location of the cellular Ca 2+ stores which probably accounts for the accelerated wave velocity at the cell periphery. 5 These data demonstrate that [Ca 2+ ] i increases, stimulated by depolarisation or the agonist ADP, have indistinguishable spatial properties, providing evidence that similar underlying mechanisms are responsible for their generation.