Regulation of glucose transport in Ca2+-tolerant myocytes from adult rat heart.
Calcium-tolerant cardiac myocytes were isolated from adult rat ventricles and sarcolemmal glucose transport was assessed by measuring linear initial uptake rates of the nonmetabolized glucose analog 3-O-methyl-D-glucose in the presence and absence of Ca2+ in the incubation medium. (1) Agents which are known to increase internal Na+ and thus stimulate Ca2+ influx via Na+-Ca2+ exchange stimulated 3-methylglucose transport in the presence of external Ca2+. These include low-Na+ medium, 10(-6) M ouabain and K+-free medium, cyanide and the sodium ionophore, monensin. Hyperosmolarity stimulated transport also in the absence of Ca2+, consistent with release of Ca2+ from internal stores. Transport was decreased in a hypo-osmolar medium and with 10(-9) M ouabain, a concentration which stimulates the Na+ pump. (2) The calcium ionophore A23187 increased basal 3-methylglucose transport but opposed stimulation of transport by insulin. (3) Insulin-stimulated transport was antagonized by palmitate and this effect was reversed by 2-bromostearate, an inhibitor of fatty acid oxidation. These results are identical in all respects to those obtained in intact cardiac and skeletal muscle preparations, confirming that hexose transport in muscle shows Ca2+ dependence and indicating that isolated cardiac myocytes are suitable for the study of this phenomenon.
I
I
Bihler
S R
SR
McNevin
P C
PC
Sawh
D019325:3-O-Methylglucose; D000818:Animals; D001692:Biological Transport / Q000187:drug effects; D000001:Calcimycin / Q000494:pharmacology; D002118:Calcium / Q000378:metabolism / Q000494:pharmacology*; D003486:Cyanides / Q000494:pharmacology; D005947:Glucose / Q000378:metabolism*; D007328:Insulin / Q000494:pharmacology; D007473:Ion Channels / Q000187:drug effects / Q000378:metabolism; D008297:Male; D008757:Methylglucosides / Q000378:metabolism; D008985:Monensin / Q000494:pharmacology; D009206:Myocardium / Q000378:metabolism*; D009994:Osmolar Concentration; D010042:Ouabain / Q000494:pharmacology; D051381:Rats; D011919:Rats, Inbred Strains; D012964:Sodium / Q000378:metabolism / Q000494:pharmacology
D003486:Cyanides; D007328:Insulin; D007473:Ion Channels; D008757:Methylglucosides; D019325:3-O-Methylglucose; D000001:Calcimycin; D010042:Ouabain; D008985:Monensin; D012964:Sodium; D005947:Glucose; D002118:Calcium