Streptozotocin-induced diabetes increases (Ca2+-Mg2+)-ATPase activity in hepatic plasma membranes of rats: involvement of protein kinase C.
The alteration in calcium transport in the liver of rats with streptozocin(STZ)-diabetic state was investigated. STZ (6 mg/100 g body weight) was subcutaneously administered in rats, and 1 or 2 weeks later they were sacrificed by bleeding. STZ administration caused a remarkable elevation of serum glucose concentration. Liver calcium content was significantly increased by STZ administration. Hepatic plasma membrane (Ca2+-Mg2+)-ATPase activity was markedly elevated by STZ administration. This increase was completely abolished by the presence of staurosporine (10(-7)-10(-5) M), an inhibitor of protein kinase C, in the enzyme reaction mixture, suggesting an involvement of protein kinase C signalling. Moreover, the STZ-induced increase in liver plasma membrane (Ca2+-Mg2+)-ATPase activity was significantly raised by the presence of okadaic acid (10(-5) and 10(-4) M). Meanwhile, the STZ-increased (Ca2+-Mg2+)-ATPase activity was not appreciably altered by the presence of anti-regucalcin IgG in the reaction mixture, indicating that the activatory protein regucalcin does not participate in the elevation of the enzyme activity. The present study demonstrates that STZ-induced diabetes causes the increase in hepatic plasma membrane (Ca2+-Mg2+)-ATPase activity of rats.
Takahashi
H
H
Laboratory of Endocrinology and Molecular Metabolism, Graduate School of Nutritional Sciences, University of Shizuoka, Shizuoka City, Japan.
Murata
T
T
Hanahisa
Y
Y
Yamaguchi
M
M
D000818:Animals; D001786:Blood Glucose / Q000378:metabolism; D017301:Ca(2+) Mg(2+)-ATPase / Q000378:metabolism*; D002118:Calcium / Q000378:metabolism; D002135:Calcium-Binding Proteins / Q000378:metabolism; D002265:Carboxylic Ester Hydrolases; D002462:Cell Membrane / Q000201:enzymology; D003921:Diabetes Mellitus, Experimental / Q000201:enzymology*; D004791:Enzyme Inhibitors / Q000494:pharmacology; D047908:Intracellular Signaling Peptides and Proteins; D008099:Liver / Q000201:enzymology*; D008297:Male; D019319:Okadaic Acid / Q000494:pharmacology; D011493:Protein Kinase C / Q000378:metabolism*; D051381:Rats; D017208:Rats, Wistar; D019311:Staurosporine / Q000494:pharmacology; D015238:Sulfotransferases
D001786:Blood Glucose; D002135:Calcium-Binding Proteins; D004791:Enzyme Inhibitors; D047908:Intracellular Signaling Peptides and Proteins; D019319:Okadaic Acid; D011493:Protein Kinase C; D015238:Sulfotransferases; C028152:alcohol sulfotransferase; D002265:Carboxylic Ester Hydrolases; C513325:Rgn protein, rat; D017301:Ca(2+) Mg(2+)-ATPase; D019311:Staurosporine; D002118:Calcium