Increased sarcolemmal Ca2+ transport activity in skeletal muscle of diabetic rats.
Sarcolemmal membranes were isolated from skeletal muscle by a sucrose density gradient method from rats with diabetes induced by a streptozotocin injection (65 mg/kg iv). The activities of Na(+)-dependent Ca2+ uptake and Ca2(+)-stimulated adenosine-triphosphatase (ATPase) in the sarcolemmal fraction from diabetic rats was higher than those from the control animals. These changes were apparent at various times of incubation (1-10 min) as well as at different concentrations of free Ca2+ (10(-7) to 10(-5) M) and developed during the third and/or fourth weeks after streptozotocin injection. ATP-dependent Ca2+ uptake in the sarcolemmal vesicles was also increased at 28 and 56 days after inducing diabetes. Treatment of diabetic animals with insulin for 14 days reversed the changes in Ca2+ transport activities toward the control levels. Sarcolemmal Mg2(+)-ATPase and Na(+)-K(+)-ATPase activities remained unchanged in diabetic preparations. Furthermore, no difference in the sarcolemmal phospholipid composition and sodium dodecyl sulfate-gel electrophoretic pattern was evident between the control and experimental groups. These results indicate a higher activity of the sarcolemmal Ca2+ transport, which may be associated with hyperfunction of the skeletal muscle in diabetic rats.
Taira
Y
Y
Division of Cardiovascular Sciences, St. Boniface General Hospital Research Centre, Winnipeg, Manitoba, Canada.
Hata
T
T
Ganguly
P K
PK
Elimban
V
V
Dhalla
N S
NS
D000818:Animals; D001693:Biological Transport, Active; D001786:Blood Glucose / Q000378:metabolism; D017301:Ca(2+) Mg(2+)-ATPase / Q000378:metabolism; D002118:Calcium / Q000378:metabolism*; D000252:Calcium-Transporting ATPases / Q000378:metabolism*; D003921:Diabetes Mellitus, Experimental / Q000378:metabolism*; D007328:Insulin / Q000097:blood; D007700:Kinetics; D008297:Male; D008563:Membrane Lipids / Q000032:analysis; D009132:Muscles / Q000378:metabolism*; D010743:Phospholipids / Q000032:analysis; D051381:Rats; D011919:Rats, Inbred Strains; D012016:Reference Values; D012508:Sarcolemma / Q000737:chemistry / Q000378:metabolism*; D000254:Sodium-Potassium-Exchanging ATPase / Q000378:metabolism
D001786:Blood Glucose; D007328:Insulin; D008563:Membrane Lipids; D010743:Phospholipids; D017301:Ca(2+) Mg(2+)-ATPase; C030704:magnesium sodium potassium ATPase; D000252:Calcium-Transporting ATPases; D000254:Sodium-Potassium-Exchanging ATPase; D002118:Calcium