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Excitation-contraction coupling of cultured human skeletal muscle cells and the relation between basal cytosolic Ca2+ and excitability.

Abstract：

:Cultured human skeletal muscle cells are frequently used as a model to study muscle pathology, in which Ca2+ homeostasis might be affected. However, their excitation-contraction (E-C) coupling has been poorly investigated. In order to elucidate E-C coupling of cultured muscle cells, we activated the acetylcholine receptors, voltage-dependent Na+ channels, dihydropyridine receptors or ryanodine receptors both in the presence and absence of external Ca2+, as well as after specific inhibition, and measured the effects on the cytosolic Ca2+ concentration ([Ca2+]i) using Fura-2. Furthermore, we examined the excitability of these cells during iterative high (125 mM) K+ stimulation with various repolarisation intervals. The resting [Ca2+]i in muscle cells of controls is about 130 nM. Acetylcholine, veratridine, high K+ and caffeine elicit dose-dependent Ca2+ transients, which are independent of extracellular Ca2+ and can be inhibited by alpha-bungarotoxin, tetrodotoxin, nifedipine or ryanodine. During repetitive K+ stimulation, the excitability of the muscle cells depends on the repolarisation interval between successive stimulations. Upon shortening the repolarisation time the Ca2+ transients become smaller and slower. Thereby, the basal [Ca2+]i rises, the Ca2+ response amplitude declines and both the half-increase and half-decay time increase. However, if the basal [Ca2+]i equals the resting [Ca2+]i the initial Ca2+ response can be recovered. The intracellular pH of 7.23, measured by BCECF, is unaffected by repeated K+ stimulation, whatever the repolarisation interval was. In conclusion, cultured human skeletal muscle cells possess a 'skeletal muscle type' of E-C coupling and their excitability at iterative stimulation is set by their basal [Ca2+]i.

journal_name

Cell Calcium

journal_title

Cell calcium

authors

Benders AA,Oosterhof A,Wevers RA,Veerkamp JH

doi

10.1016/s0143-4160(97)90099-3

subject

Has Abstract

pub_date

1997-01-01 00:00:00

pages

81-91

issue

eissn

0143-4160

issn

1532-1991

pii

S0143-4160(97)90099-3

journal_volume

pub_type

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Excitation-contraction coupling of cultured human skeletal muscle cells and the relation between basal cytosolic Ca2+ and excitability.