Energy restriction suppresses microsomal Ca(2+)-ATPase activities in various organs in C57BL/6 female mice in both euthermic and torpor states.
C57BL/6 female mice were fed a daily control diet (n = 5, 3.9 g/day, 95 kcal/week) or ER diet (n = 5, 2.3 g/day, 48 kcal/week) at 1800 h from 6 weeks of age. Telemetry, conducted at 6 months of age, confirmed that all ER mice entered daily torpor (core body temperature less than 31 degrees C) for 6.63 +/- 2.34 h/day while control mice were euthermic (> 35 degrees C). In vitro activities of microsomal Ca(2+)-ATPase were determined in the brain, liver, salivary gland and kidney from these mice at 6 months of age. Assays were performed at three incubation temperatures of 37 degrees C, 31 degrees C and 25 degrees C. In assays at 37 degrees C, the activities of Ca(2+)-ATPase in the brain and salivary gland from ER mice were lower than those in corresponding organs from control mice. The suppression became profound as the incubation temperature decreased. On the other hand, at 37 degrees C Ca(2+)-ATPase activities in the liver and kidney from ER mice were not lower than those in corresponding organs from control mice, but decreased significantly at low temperatures. Microsomal Ca(2+)-ATPase activities thus appeared to be reduced in ER mice, although it remains unknown whether the present results represent reduced in vivo capacities to regulate cytosolic Ca2+ concentrations.
Tsukada
M
M
Department of Hygiene, Akita University School of Medicine, Japan.
Hamade
N
N
Wada
Y
Y
Mogi
T
T
Kamiyama
S
S
Koizumi
A
A
D000818:Animals; D001831:Body Temperature / Q000502:physiology*; D000252:Calcium-Transporting ATPases / Q000378:metabolism*; D004032:Diet; D004734:Energy Metabolism / Q000502:physiology*; D005260:Female; D051379:Mice; D008810:Mice, Inbred C57BL; D008861:Microsomes / Q000201:enzymology*; D009928:Organ Specificity / Q000502:physiology; D013997:Time Factors
D000252:Calcium-Transporting ATPases