Intracellular pH regulation in isolated fast-twitch skeletal muscle from dystrophin-deficient mouse.
In muscles from anaesthetized dystrophin-deficient mdx mice, exercise results in a stronger acidification and a slower intracellular pH recovery compared to control mice. We examined whether this observation could be attributed to defective H+-carriers in dystrophin-lacking muscles. Immunohistochemistry and Western blots revealed no defect in mdx muscles for the presence of the lactate-/H+co-transporter MCT4 and of the Na+/H+ antiporter NHE1, the main H+-carriers active in fast-twitch skeletal muscle after exercise. Functional tests of the H+-transporters, on isolated muscles submitted to identical flow of superfusion, were performed in conditions meant to lower intracellular pH: repetitive electrical stimulation or NH4Cl pre-pulse. These revealed no defect in intracellular pH recovery in mdx muscles. Therefore, we conclude that impaired intracellular pH regulation in anaesthetized mdx mice is not attributable to a reduced presence or activity of H+-extruders. We propose that CO2 washout might be slowed down in vivo in mdx muscles because of the defective vascular response in contracting muscles from these mice.
Decostre
V
V
Département de Physiologie, Faculté de Médecine, Université Catholique de Louvain, Brussels, Belgium.
Gailly
P
P
Debaix
H
H
Colson-Van Schoor
M
M
Cao
M L
ML
Gillis
J M
JM
D000818:Animals; D016189:Dystrophin / Q000172:deficiency*; D006859:Hydrogen / Q000378:metabolism*; D006863:Hydrogen-Ion Concentration; D066298:In Vitro Techniques; D007425:Intracellular Membranes / Q000378:metabolism*; D008661:Metabolism, Inborn Errors / Q000378:metabolism*; D051379:Mice; D008810:Mice, Inbred C57BL; D018101:Mice, Inbred mdx; D027501:Monocarboxylic Acid Transporters / Q000378:metabolism; D018656:Muscle Fibers, Fast-Twitch / Q000378:metabolism*; D009124:Muscle Proteins; D018482:Muscle, Skeletal / Q000378:metabolism*; D020033:Protein Isoforms / Q000378:metabolism; D017923:Sodium-Hydrogen Exchangers / Q000378:metabolism
D016189:Dystrophin; D027501:Monocarboxylic Acid Transporters; D009124:Muscle Proteins; D020033:Protein Isoforms; C498648:Slc16a4 protein, mouse; D017923:Sodium-Hydrogen Exchangers; D006859:Hydrogen