Effects of sphingosine 1-phosphate on excitation-contraction coupling in mammalian skeletal muscle

Year: 2003

Authors: Bencini C., Squecco R., Piperio C., Formigli L., Meacci E., Nosi D., Tiribilli B., Vassalli M., Quercioli F., Bruni P., Orlandini Zecchi S., Francini F.

Autors Affiliation: Department of Physiological Sciences, University of Florence, Viale GB. Morgagni 64, 50134 Firenze, Italy;
Department of Anatomy, Histology and Forensic Sciences, Viale GB. Morgagni 85, 50134 Firenze, Italy;
Department of Biochemical Sciences, Viale GB. Morgagni 50, 50134 Firenze, Italy;
Istituto Nazionale di Ottica Applicata, Laboratorio di biofotonica, Largo E. Fermi 6, 50125 Firenze, Italy

Abstract: Sphingosine 1- phosphate ( S1P) activates a subset of plasma membrane receptors of the endothelial differentiation gene family ( EdgRs) in many cell types. In C2C12 myoblasts, exogenous S1P elicits Ca2+ transients by activating voltage- independent plasma membrane Ca2+ channels and intracellular Ca2+- release channels. In this study, we investigated the effects of exogenous S1P on voltage- dependent L- type Ca2+ channels in skeletal muscle fibers from adult mice. To this end, intramembrane charge movements ( ICM) and L- type Ca (2+) current ( I-Ca) were measured in single cut fibers using the double Vaseline- gap technique. Our data showed that submicromolar concentrations of S1P ( 100 nM) caused a similar to 10- mV negative shift of the voltage threshold and transition voltages of q(gamma) and q(h) components of ICM, and of ICa activation and inactivation. Biochemical studies showed that EdgRs are expressed in skeletal muscles. The involvement of EdgRs in the above S1P effects was tested with suramin, a specific inhibitor of Edg- 3Rs. Suramin ( 200 muM) significantly reduced, by similar to 90%, the effects of S1P on ICM and I-Ca, suggesting that most of S1P action occurred via Edg- 3Rs. Moreover, S1P at concentration above 10 muM elicited intracellular Ca2+ transients in muscle fibers loaded with the fluorescent Ca2+ dye Fluo- 3, as detected by confocal laser scanning microscopy.

Journal/Review: JOURNAL OF MUSCLE RESEARCH AND CELL MOTILITY

Volume: 24 (8)      Pages from: 539  to: 554

More Information: The Authors thank Dr A. Tani for technical support in calcium transients experiments. This work was supported by grant 945 from Telethon, Italy and Cofinanzia-mento Ministero dell’Università e della Ricerca Scientifica e Tecnologica (MURST) 1999.
KeyWords: calcium; sphingosine 1 phosphate; suramin, animal cell; animal tissue; article; cell differentiation; cell membrane; cell type; controlled study; endothelium cell; excitation contraction coupling; male; mouse; multigene family; myoblast; nonhuman; priority journal; skeletal muscle, Animals; Calcium; Calcium Channels, L-Type; Calcium Signaling; Electrophysiology; Fluorescent Dyes; Lysophospholipids; Membrane Potentials; Mice; Muscle Contraction; Myofibrils; Sphingosine, Animalia; Mammalia
DOI: 10.1023/B:JURE.0000009898.02325.58

Citations: 25
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