Insulin stimulation of intracellular free Ca2+ recovery and Ca(2+)-ATPase gene expression in cultured vascular smooth-muscle cells: role of glucose 6-phosphate.
Wa have previously reported that insulin accelerates recovery of intracellular Ca2+ concentrations ([Ca2+]i) from pressor agonist-induced Ca2+ loads and stimulates both plasmalemmal and sarcoplasmic-reticulum Ca(2+)-ATPase gene expression in cultured and freshly isolated vascular smooth-muscle cells (VSMCs), suggesting that insulin attenuation of vascular tone may result from modulation of [Ca2+]i. Accordingly, we have now evaluated the linkage between this insulin-regulation of VSMC[Ca2+]i and classical actions of insulin (i.e. glucose transport and metabolism). Cultured VSMCs were incubated in the presence or absence of insulin in a medium containing either pyruvate, glucose, 3-O-methylglucose or 2-deoxyglycose. Insulin caused an 87% increase in [Ca2+]i recovery rate after stimulation with arginine-vasopressin (P < 0.01) and caused a marked increase in Ca(2+)-ATPase mRNA and protein levels in the presence of glucose. Comparable increases in both [Ca2+]i recovery and Ca2(+)-ATPase expression were found when glucose was replaced by 2-deoxyglucose. In contrast, no stimulation was found in either the glucose-free or 3-O-methylglucose-containing medium. As both glucose analogues are transported, but only 2-deoxyglucose is phosphorylated, this indicates that glucose transport and metabolism to glucose 6-phosphate is essential for insulin regulation of VSMC [Ca2+]i, possibly via a glucose-6-phosphate-dependent carbohydrate-response element in the Ca2(+)-ATPase gene.
D000818:Animals; D001127:Arginine Vasopressin / Q000494:pharmacology; D001483:Base Sequence; D015152:Blotting, Northern; D002118:Calcium / Q000378:metabolism*; D000252:Calcium-Transporting ATPases / Q000235:genetics / Q000378:metabolism*; D002460:Cell Line; D002478:Cells, Cultured; D016384:Consensus Sequence; D003847:Deoxyglucose / Q000494:pharmacology; D016257:Fura-2 / Q000378:metabolism; D015971:Gene Expression Regulation, Enzymologic; D005947:Glucose / Q000494:pharmacology; D019298:Glucose-6-Phosphate; D005958:Glucosephosphates / Q000502:physiology*; D007328:Insulin / Q000494:pharmacology*; D008969:Molecular Sequence Data; D009131:Muscle, Smooth, Vascular / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D011773:Pyruvates / Q000494:pharmacology; D019289:Pyruvic Acid; D012333:RNA, Messenger / Q000378:metabolism; D051381:Rats; D011924:Rats, Zucker
D005958:Glucosephosphates; D007328:Insulin; D011773:Pyruvates; D012333:RNA, Messenger; D001127:Arginine Vasopressin; D019298:Glucose-6-Phosphate; D019289:Pyruvic Acid; D003847:Deoxyglucose; D000252:Calcium-Transporting ATPases; D005947:Glucose; D002118:Calcium; D016257:Fura-2