Effects of food restriction and insulin treatment on (Ca2+ + Mg2+)-ATPase response to insulin in kidney basolateral membranes of noninsulin-dependent diabetic rats.
Insulin increases (Ca2+ + Mg2+)-ATPase activity in cell membranes of normal rats but fails to do so in membranes of non-insulin-dependent diabetic (NIDD) rats. The loss of regulatory effect of the hormone on the enzyme might contribute to the insulin resistance observed in the NIDD animals. To further test this hypothesis, the effects of insulin treatment and acute food restriction on the ability of insulin to regulate the ATPase activity in kidney basolateral membranes (BLM) of NIDD rats were studied. Although insulin levels in NIDD and control rats were similar, plasma glucose was higher in the NIDD rats (18.3 +/- 1.5 v 19.3 +/- 1.7 microU/mL and 236 +/- 32 v 145 +/- 3 mg/dL, respectively). Insulin treatment (2 U/100 g), which increased plasma insulin in the NIDD rats (47.8 +/- 11.5 microU/mL; P less than .05), did not decrease their glucose (221 +/- 25 mg/dL). Higher insulin dose (4 U/100 g) decreased glucose level in the NIDD rats (73 +/- 3 mg/dL; P less than .001) but increased their plasma insulin 10-fold (202.5 +/- 52.5 microU/mL). Acute food restriction decreased glucose levels in the NIDD rats to levels seen in controls (135 +/- 3 mg/dL), while their insulin decreased by half (8.5 +/- 1.0 microU/mL; P less than .05). Basal (Ca2+ + Mg2+)-ATPase activity in BLM of all diabetic rats was higher than in controls (P less than .05). None of the treatments reversed this defect.(ABSTRACT TRUNCATED AT 250 WORDS)
Levy
J
J
Division of Metabolism, Washington University School of Medicine, St. Louis, MO.
Grunberger
G
G
Karl
I
I
Gavin
J R
JR
D000818:Animals; D001485:Basement Membrane / Q000187:drug effects; D001786:Blood Glucose / Q000032:analysis; D017301:Ca(2+) Mg(2+)-ATPase / Q000378:metabolism*; D000252:Calcium-Transporting ATPases / Q000378:metabolism*; D046508:Culture Techniques; D003921:Diabetes Mellitus, Experimental / Q000201:enzymology*; D003924:Diabetes Mellitus, Type 2 / Q000201:enzymology*; D004305:Dose-Response Relationship, Drug; D004789:Enzyme Activation / Q000187:drug effects; D005215:Fasting; D007328:Insulin / Q000494:pharmacology*; D007333:Insulin Resistance; D007668:Kidney / Q000187:drug effects / Q000201:enzymology*; D051381:Rats; D011919:Rats, Inbred Strains
D001786:Blood Glucose; D007328:Insulin; D017301:Ca(2+) Mg(2+)-ATPase; D000252:Calcium-Transporting ATPases