Expression of sarcoplasmic reticulum ca2+ transport proteins in cold acclimating ducklings. Dumonteil, Eric, Herv[acute]e Barr[acute]e, and Gerhard Meissner. Department of Biochemistry and Biophysics, University of North Carolina at Chapel Hill, NC 27599-7260, USA, Laboratoire de Physiologie G[acute]en[acute]erale et Compar[acute]ee, Universit[acute]e Lyon I, 43 Bd. du 11 Novembre 1918, Villeurbanne Cedex, and Unit[acute]e de Recherche Associ[acute]ee 1341 Centre National de la Recherche Scientifique, 8 Av. Rockfeller, 69373 Lyon cedex 08, France, Current address: Clinical Diabetology, University of Geneva, Centre Medical Universitaire, CH-1211 Geneve 4
APStracts 2:0194C, 1995.
The relationship between the cold-induced increase in sarcoplasmic reticulum (SR) Ca2+ transport proteins and the development of muscular non-shivering thermogenesis (NST) was investigated by determining the time course of expression of Ca2+-ATPase (SERCA), Ca2+ release channel, and calsequestrin in control and cold acclimating ducklings. 45Ca2+ uptake and [3H]ryanodine binding measurements with skeletal muscle homogenates showed that a cold acclimation period of about 4 weeks was required to observe a substantial increase in Ca2+-ATPase activity and Ca2+ release channel content, which correlates well with NST development. Immunoblot analysis of muscle homogenates showed no differences in calsequestrin levels, but revealed that the decrease in SERCA2a content was delayed in cold acclimating birds, and that SERCA1 level was increased after 4 weeks of cold acclimation. The persistence of SERCA2a may be related to shivering thermogenesis occurring preferentially in slow twitch fibers. SERCA1 may account for most of the cold-induced increase in 45Ca2+ uptake activity, suggesting the preferential occurrence of a Ca2+-dependent NST in fast twitch fibers. 

Received 20 January 1995; accepted in final form 2 May 1995.
APS Manuscript Number C41-5.
Article publication pending Am. J. Physiol. (Cell Physiology).
ISSN 1080-4757 Copyright 1995 The American Physiological Society.
Published in APStracts on 16 May 1995.