Effects of acidosis and inorganic phosphate on Ca ²⁺ sensitivity of young and older adult skeletal muscle fibers

This study reports the effects of elevated H + and P i on Ca 2+ sensitivity of human skeletal muscle fibers and determines whether the effects of these metabolites are altered by aging in submaximal Ca 2+ . The metabolites markedly depressed Ca 2+ sensitivity in human muscle fibers, but there was no effect of age or sex. These data suggest that Ca 2+ sensitivity is preserved with age in conditions that mimic both quiescent and fatigued muscle.