Changes in cytosolic resting ionized calcium level and in calcium transients during in vitro development of normal and Duchenne muscular dystrophy cultured skeletal muscle measured by laser cytofluorimetry using indo-1.
Intracellular calcium activity was recorded during in vitro myogenesis of human normal and DMD muscle, using the calcium probe Indo-1 under laser illumination, at rest and during different kinds of stimulation (acetylcholine, high K+, caffeine). In myoblasts, the resting intracellular calcium level was significantly larger in DMD cells (89 +/- 9 nM; n = 40 vs 37 +/- 5 nM; n = 22) but there was no significant difference in myotubes, after fusion (44 +/- 4 nM; n = 34 vs 36 +/- 4 nM; n = 52). A similar evolution was observed in cells cultured from FSH biopsies. The amplitude of ACh- and high K(+)-induced calcium transients was significantly halved in DMD myotubes as compared to control ones and non-significantly decreased for caffeine responses. Some alterations in the kinetics of responses were observed in DMD muscle: the rising phases of ACh- and high K(+)-elicited transients and the decaying phase of the ACh-responses were significantly slowed down. It is concluded that: (i) in aneurally cultured human muscle, an increase in the basal level of internal calcium can occur at early stages of myogenesis before the expression of the dystrophin gene; and (ii) the changes in calcium transients induced by depolarization or direct stimulation of sarcoplasmic reticulum are not susceptible of inducing a calcium overload in DMD cells.
Rivet-Bastide
M
M
Laboratoire de Physiologie Générale, URA CNRS n 290, Université de Poitiers, France.
Imbert
N
N
Cognard
C
C
Duport
G
G
Rideau
Y
Y
Raymond
G
G
D000109:Acetylcholine / Q000494:pharmacology; D000293:Adolescent; D000328:Adult; D002110:Caffeine / Q000494:pharmacology; D002118:Calcium / Q000378:metabolism*; D002478:Cells, Cultured; D002648:Child; D003600:Cytosol / Q000378:metabolism*; D005470:Fluorometry; D006801:Humans; D007211:Indoles / Q000378:metabolism; D007834:Lasers; D009132:Muscles / Q000187:drug effects / Q000378:metabolism* / Q000473:pathology; D009136:Muscular Dystrophies / Q000378:metabolism* / Q000473:pathology; D011188:Potassium / Q000494:pharmacology
D007211:Indoles; D002110:Caffeine; C048960:indo-1; D000109:Acetylcholine; D011188:Potassium; D002118:Calcium