G protein effects on Ca2+ release and excitation-contraction coupling in skeletal muscle fibers

• DOI: 10.1152/ajpcell.1994.267.4.c1087
• Publication Date: 2017-12-24T17:45:38Z
• Authors: L. Carney-Anderson; S. K. Donaldson
• Keywords: 0301 basic medicine; Rest; Cell Membrane; Cell Polarity; 03 medical and health sciences; GTP-Binding Proteins; Guanosine 5'-O-(3-Thiotriphosphate); Animals; Calcium; Female; Guanosine Triphosphate; Rabbits; Muscle, Skeletal; Muscle Contraction

Skeletal muscle excitation-contraction (EC) coupling may involve secondary mechanisms, such as those involving G proteins. The aim of this study was to identify possible protein effects on sarcoplasmic reticulum (SR) Ca2+ release, in general, and voltage-dependent EC coupling, particular. Effects guanosine 5'-O-(3-thiotriphosphate) (GTP gamma S) were studied using a single peeled rabbit skeletal fiber preparation that is capable releasing SR response transverse tubule (TT) depolarization. Because nonspecific residual 200 microM GTP S, lower concentration 50 S used stimulate proteins the system. Under conditions for steady-state (resting) polarization TT, rarely elicited release. When TTs are depolarization, or release associated tension transients only 69% fibers tested. In contrast always augmented during TT depolarization-induced coupling. These results indicate presence at least two excitatory one which modulator, albeit nonessential,