Key Points
- The study aims to determine how parvalbumin influences muscle relaxation when the sarcoplasmic reticulum Ca(2+)-ATPase is inhibited.
- Inhibition of Ca(2+)-ATPase with 2,5-di-(tert-butyl)-1,4-benzohydroquinone (TBQ) in frog skeletal muscle fibers at 10 degrees C.
- Measurement of twitch force, Ca2+ transients, and relaxation rates after TBQ application.
- TBQ prolonged the half time of the fall of the Ca2+ transient by 62%.
- Twitch force increased by 100% and peak force by 120% without an increase in Ca2+ amplitude.
- Relaxation rate decreased to a time course of approximately 2 s-1, resembling the Mg2+ off rate from parvalbumin.
Structured PICO
PPopulationFrog skeletal muscle fibers
IInterventionInhibition of sarcoplasmic reticulum (SR) Ca(2+)-ATPase with 2,5-di-(tert-butyl)-1,4-benzohydroquinone (TBQ) at 10 degrees C
CComparatorBaseline/uninhibited state
OOutcomeCa2+ transient half-time and twitch forcesurrogate
In frog skeletal muscle, when SR Ca(2+)-ATPase is inhibited, Mg(2+)-parvalbumin can sequester Ca2+ and produce relaxation at a rate defined by the Mg2+ off rate from parvalbumin.