Lack of dystrophin but normal calcium homeostasis in smooth muscle from dystrophic mdx mice.
The free cytosolic Ca2+ concentration ([Ca2+]i) in the dystrophin-lacking smooth muscle from mdx mice was studied to gain new insights into the relation between dystrophin and cytoplasmic Ca2+ homeostasis, which was reported to be impaired in the mdx skeletal muscle. We observed that [Ca2+]i, as measured with the fluorescent Ca2+ indicator fura-2, was not elevated in resting smooth muscle of the vas deferens from mdx mice, in comparison with control C57 mice. Changes of the external Ca2+ concentration evoked similar changes of [Ca2+]i in mdx and control vas deferens. During contraction, cytosolic Ca2+ transients were identical, both in amplitude and in kinetics, whether or not dystrophin was present. Stretches evoked similar Ca2+ increases in muscles from both strains. Intracellular Ca2+ homeostasis appears to be unimpaired in mdx smooth muscle. Thus, the lack of dystrophin per se does not automatically induce a perturbation of Ca metabolism in muscle cells.
Boland
B
B
Department of Physiology, Université Catholique de Louvain, Bruxelles, Belgium.
Himpens
B
B
Casteels
R
R
Gillis
J M
JM
D000818:Animals; D002118:Calcium / Q000378:metabolism*; D016189:Dystrophin / Q000172:deficiency* / Q000502:physiology; D016257:Fura-2; D006706:Homeostasis; D008297:Male; D051379:Mice; D008817:Mice, Mutant Strains; D009130:Muscle, Smooth / Q000378:metabolism*; D014649:Vas Deferens / Q000378:metabolism
D016189:Dystrophin; D002118:Calcium; D016257:Fura-2