Rapid cooling contractures in rat skinned myocardium: effects of
isoflurane and halothane.
Herland, J., F. J. Julian & D. G. Stephenson.
School of Zoology, La Trobe University, Bundoora, Victoria 3083,
Australia and the Department of Anesthesia Research Laboratories,
Brigham and Women's Hospital, Boston, MA 02115 USA
APStracts 2:0481H, 1995.
Rapid cooling contractures (RCCs) have been elicited in rat
ventricular cardiac muscle skinned by saponin (50[mu]g/ml). The size
and shape of the RCC in skinned cardiac muscle were similar to those
observed in intact cardiac muscle. The ATP-dependent Ca2+ uptake pump
in the sarcoplasmic reticulum (SR) was active at low temperature and
could efficiently load the SR with Ca2+ even at 3 degrees C.
Halothane reduced both the RCC and caffeine contracture in a dose
-dependent way when halothane treatment was applied prior to either
the RCC or caffeine. This action is consistent with halothane-induced
depletion of the SR Ca2+. Under similar conditions, isoflurane
inhibited the RCC while having little effect on the caffeine
contracture. This may suggest that rapid cooling and caffeine have
different modes of action on the SR Ca2+-release channel. Our results
provide further strong supporting evidence for differential
inhibitory actions on a key intracellular organelle in cardiac muscle
by two vapor anesthetic agents.
Received 14 November 1995; accepted in final form 21 September
1995.
APS Manuscript Number H1020-4.
Article publication pending Am. J. Physiol. (Heart Circ. Physiology).
ISSN 1080-4757 Copyright 1995 The American Physiological Society.
Published in APStracts on 6 November 95