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Sub-plasmalemmal [Ca2+]i upstroke in myocytes of the guinea-pig small intestine evoked by muscarinic stimulation: IP3R-mediated Ca2+ release induced by voltage-gated Ca2+ entry.

Gordienko, DV; Harhun, MI; Kustov, MV; Pucovský, V; Bolton, TB (2008) Sub-plasmalemmal [Ca2+]i upstroke in myocytes of the guinea-pig small intestine evoked by muscarinic stimulation: IP3R-mediated Ca2+ release induced by voltage-gated Ca2+ entry. Cell Calcium, 43 (2). pp. 122-141. ISSN 0143-4160 https://doi.org/10.1016/j.ceca.2007.04.012
SGUL Authors: Bolton, Thomas Bruce Gordienko, Dmytro Valerjevich Harhun, Maksym

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Abstract

Membrane depolarization triggers Ca(2+) release from the sarcoplasmic reticulum (SR) in skeletal muscles via direct interaction between the voltage-gated L-type Ca(2+) channels (the dihydropyridine receptors; VGCCs) and ryanodine receptors (RyRs), while in cardiac muscles Ca(2+) entry through VGCCs triggers RyR-mediated Ca(2+) release via a Ca(2+)-induced Ca(2+) release (CICR) mechanism. Here we demonstrate that in phasic smooth muscle of the guinea-pig small intestine, excitation evoked by muscarinic receptor activation triggers an abrupt Ca(2+) release from sub-plasmalemmal (sub-PM) SR elements enriched with inositol 1,4,5-trisphosphate receptors (IP(3)Rs) and poor in RyRs. This was followed by a lesser rise, or oscillations in [Ca(2+)](i). The initial abrupt sub-PM [Ca(2+)](i) upstroke was all but abolished by block of VGCCs (by 5 microM nicardipine), depletion of intracellular Ca(2+) stores (with 10 microM cyclopiazonic acid) or inhibition of IP(3)Rs (by 2 microM xestospongin C or 30 microM 2-APB), but was not affected by block of RyRs (by 50-100 microM tetracaine or 100 microM ryanodine). Inhibition of either IP(3)Rs or RyRs attenuated phasic muscarinic contraction by 73%. Thus, in contrast to cardiac muscles, excitation-contraction coupling in this phasic visceral smooth muscle occurs by Ca(2+) entry through VGCCs which evokes an initial IP(3)R-mediated Ca(2+) release activated via a CICR mechanism.

Item Type: Article
Additional Information: © 2007 Elsevier Ltd. Made available under the terms and conditions of the CC-BY 3.0 license http://creativecommons.org/licenses/by/3.0/
Keywords: Animals, Boron Compounds, Calcium, Calcium Signaling, Carbachol, Cell Membrane, Evoked Potentials, Guinea Pigs, Ileum, Inositol 1,4,5-Trisphosphate Receptors, Isometric Contraction, Macrocyclic Compounds, Male, Myocytes, Smooth Muscle, Nicardipine, Oxazoles, Receptors, Muscarinic, Ryanodine Receptor Calcium Release Channel, Tetracaine, smooth muscle cells, muscarinic receptors, IP3 receptors, ryanodine receptors, confocal microscopy, Ca2+-induced Ca2+ release, E-C coupling, Ileum, Cell Membrane, Myocytes, Smooth Muscle, Animals, Guinea Pigs, Boron Compounds, Calcium, Carbachol, Tetracaine, Oxazoles, Nicardipine, Macrocyclic Compounds, Ryanodine Receptor Calcium Release Channel, Receptors, Muscarinic, Calcium Signaling, Evoked Potentials, Isometric Contraction, Male, Inositol 1,4,5-Trisphosphate Receptors, Science & Technology, Life Sciences & Biomedicine, Cell Biology, CELL BIOLOGY, smooth muscle cells, muscarinic receptors, IP3 receptors, ryanodine receptors, confocal microscopy, Ca2+-induced Ca2+ release, E-C coupling, SMOOTH-MUSCLE-CELLS, TRANSIENT OUTWARD CURRENTS, INDUCED CALCIUM-RELEASE, INOSITOL 1,4,5-TRISPHOSPHATE RECEPTORS, OPERATED CATION CURRENT, MOUSE URINARY-BLADDER, PORTAL-VEIN MYOCYTES, RYANODINE RECEPTORS, SARCOPLASMIC-RETICULUM, ION CHANNELS, Biochemistry & Molecular Biology, 0601 Biochemistry And Cell Biology, 0606 Physiology, 1116 Medical Physiology
Journal or Publication Title: Cell Calcium
ISSN: 0143-4160
Dates:
DateEvent
February 2008Published
PubMed ID: 17570487
Web of Science ID: WOS:000254158600003
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URI: https://openaccess.sgul.ac.uk/id/eprint/1596
Publisher's version: https://doi.org/10.1016/j.ceca.2007.04.012

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