AJP - Regulatory, Integrative and Comparative Physiology, Vol 256, Issue 1 201-R206, Copyright © 1989 by American Physiological Society
Skeletal muscle calcium uptake in bacteremic rats
M. V. Westfall and M. M. Sayeed
Department of Physiology, Loyola University Stritch School of Medicine, Maywood, Illinois 60153.
To determine whether cellular Ca2+ regulation is altered in bacteremic rat
skeletal muscle, 45Ca2+ uptake was measured in soleus muscles 12 h after an
intraperitoneal bacterial (Escherichia coli) injection. Some rats received
diltiazem (2.4 mg/kg iv) 10 h after bacterial injection to determine
whether calcium blockers could inhibit changes in Ca2+ regulation. Cellular
exchangeable Ca2+ was measured in soleus muscles incubated for 5 min to 4 h
in Krebs-Ringer bicarbonate (KRB) media (pH 7.4) containing 45Ca2+ (1.5
muCi/ml) and subsequently "washed" in La3+-containing, Ca2+-free KRB media.
Bacteremia had no effect on steady-state exchangeable Ca2+, but it
significantly reduced the time required to reach half-maximal uptake
compared with controls. Diltiazem treatment returned the half-maximal Ca2+
uptake toward control values in bacteremic rat muscles. Depolarization of
soleus muscles with high K+ (60 mM) transiently increased Ca2+ uptake in
control and bacteremic rat muscles, although the increase was significantly
greater (P less than 0.05) in bacteremic rat muscles. The altered skeletal
muscle Ca2+ regulation may be due to excessive stimulation of Ca2+
messenger systems, sarcolemmal Ca2+ channels, and/or Ca2+ release from the
sarcoplasmic reticulum in response to bacteremia.
