Procaine enhancement of the rapid cooling contracture and inhibition of the decay of potentiated state in rabbit papillary muscle.
We tested the possibility that inhibition of Ca2+ release from the sarcoplasmic reticulum decreases the transsarcolemmal Ca2+ efflux and results in an increased sarcoplasmic reticulum Ca2+ content. We used procaine to inhibit sarcoplasmic reticulum Ca2+ release in rabbit papillary muscles. Rapid cooling-induced contractures were used as an index of sarcoplasmic reticulum Ca2+ content. Decay of potentiated state was measured to study whether the transsarcolemmal Ca2+ efflux is decreased in the presence of procaine. Procaine (0.5, 1.0 mM) inhibited contractions elicited by electrical stimulation and enhanced the rapid cooling-induced contracture. The initial decay of potentiated state that occurs when the muscle was stimulated at a low frequency was slowed in the presence of procaine. These results suggest that procaine inhibition of Ca(2+)-induced release of sarcoplasmic reticulum Ca2+ decreases the transsarcolemmal Ca2+ efflux relative to the influx, resulting in an increased sarcoplasmic reticulum Ca2+ content.
Komai
H
H
Department of Anesthesiology, University of Wisconsin, Madison 53792-3272, USA.
Redon
D
D
Rusy
B F
BF
D000818:Animals; D002118:Calcium / Q000378:metabolism*; D006352:Heart Ventricles / Q000187:drug effects*; D066298:In Vitro Techniques; D009119:Muscle Contraction; D010210:Papillary Muscles / Q000187:drug effects*; D011343:Procaine / Q000494:pharmacology*; D011817:Rabbits
D011343:Procaine; D002118:Calcium