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Altered sarcoplasmic reticulum function after high-intensity exercise.

S K Byrd·L J McCutcheon·D R Hodgson·P D Gollnick
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Abstract

This study examined the effects of acute high-intensity exercise on the rate and capacity of Ca2+ uptake and Ca2+-stimulated adenosinetriphosphatase (ATPase) activity of the sarcoplasmic reticulum and the reversibility of these effects. Thoroughbred horses were run at maximal O2 uptake on a high-speed treadmill until fatigued. Muscle temperatures and biopsy samples were collected at rest, immediately after exercise, and 30 and 60 min after exercise. Blood samples were collected at rest and 5 min after exercise. Muscle and blood (lactate concentration) were three- and fivefold greater than pre-exercise values. Muscle temperature and pH immediately after post-exercise were 43 degrees C and 6.55, respectively, but approached rest values by 60 min after exercise. The initial rate and maximal capacity of Ca2+ uptake of muscle homogenates and isolated sarcoplasmic reticulum were significantly depressed immediately after exercise. This depression was paralleled by decreased activity of the Ca2+-stimulated ATPase. However, both Ca2+ uptake (rate and capacity) and Ca2+4-ATPase activity had returned to normal by 60 min after exercise. These findings demonstrate that changes in sarcoplasmic reticulum function after high-intensity exercise may be induced but not sustained by local changes in muscle pH and/or temperature.

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Analysis of VarianceAnimalsBody TemperatureCa(2+) Mg(2+)-ATPaseCalciumCalcium-Transporting ATPasesFemaleHorsesHydrogen-Ion ConcentrationMaleMusclesOxygen ConsumptionPhysical ExertionSarcoplasmic ReticulumJournal ArticleResearch Support, Non-U.S. Gov'tResearch Support, U.S. Gov't, P.H.S.

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S K Byrd, L J McCutcheon, D R Hodgson, P D Gollnick. 1989. Altered sarcoplasmic reticulum function after high-intensity exercise.. https://doi.org/10.1152/jappl.1989.67.5.2072

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