GLUCOSE-TRANSPORT AND PHOSPHORYLATION IN SINGLE CARDIAC MYOCYTES - RATE-LIMITING STEPS IN GLUCOSE-METABOLISM

被引:86
作者
MANCHESTER, J [1 ]
KONG, XM [1 ]
NERBONNE, J [1 ]
LOWRY, OH [1 ]
LAWRENCE, JC [1 ]
机构
[1] WASHINGTON UNIV,SCH MED,DEPT MOLEC BIOL & PHARMACOL,ST LOUIS,MO 63110
来源
AMERICAN JOURNAL OF PHYSIOLOGY | 1994年 / 266卷 / 03期
关键词
MICROANALYTIC METHODS; GLUCOSE PHOSPHORYLATION; HEXOKINASE;
D O I
10.1152/ajpendo.1994.266.3.E326
中图分类号
Q4 [生理学];
学科分类号
071003 ;
摘要
Microanalytic methods were used to investigate the regulation of glucose metabolism by insulin in single myocytes isolated from adult rat ventricles. Cultured myocytes were incubated with or without insulin and, with either glucose or 8-deoxyglucose (2-DG), rinsed, and freeze-dried. Individual cells were weighed and levels of 2-DG-6-phosphate (2-DG-6-P) or glucose and glucose 6-phosphate (G-6-P) were determined after enzymatic amplification. In cells incubated with 2-DG, insulin increased the level of 2-DG-6-P by as much as 30-fold, indicative of dramatic activation of glucose transport. In cells incubated with glucose, insulin increased the levels of G-6-P by approximately threefold. Increasing extracellular glucose without insulin also increased G-6-P; however, intracellular glucose concentrations were not increased, indicating that glucose transport is rate limiting in nonstimulated myocytes. In contrast, intracellular glucose concentrations were increased by over an order of magnitude by insulin, reaching 60% of the extracellular glucose concentration. Measurements of glucose and G-6-P in the same insulin-treated cells revealed that accumulation of G-6-P reached a plateau when extracellular glucose was increased >2 mM. At this point the estimated intracellular glucose concentration was 300 mu M, or approximately 10 times the Michaelis constant of hexokinase for glucose. These results indicate that in the presence of insulin and physiological concentrations of glucose, hexokinase is saturated with glucose. Consequently, the rate-limiting step for insulin-stimulated glucose utilization is glucose phosphorylation rather than glucose transport.
引用
收藏
页码:E326 / E333
页数:8
相关论文
共 35 条
[1]   INSULIN BINDING AND GLUCOSE-TRANSPORT ACTIVITY IN CARDIOMYOCYTES OF A DIABETIC RAT [J].
ALMIRA, EC ;
GARCIA, AR ;
BOSHELL, BR .
AMERICAN JOURNAL OF PHYSIOLOGY, 1986, 250 (04) :E402-E406
[2]  
BAILEY JM, 1972, BIOCHEM BIOPH RES CO, V46, P191
[3]   GLUCOSE-METABOLISM IN PERFUSED SKELETAL-MUSCLE - INTERACTION OF INSULIN AND EXERCISE ON GLUCOSE-UPTAKE [J].
BERGER, M ;
HAGG, S ;
RUDERMAN, NB .
BIOCHEMICAL JOURNAL, 1975, 146 (01) :231-238
[4]   REGULATION OF GLUCOSE-TRANSPORT IN CA-2+-TOLERANT MYOCYTES FROM ADULT-RAT HEART [J].
BIHLER, I ;
MCNEVIN, SR ;
SAWH, PC .
BIOCHIMICA ET BIOPHYSICA ACTA, 1985, 846 (02) :208-215
[5]   A NOVEL TYPE OF DEPOLARIZATION-ACTIVATED K+ CURRENT IN ISOLATED ADULT-RAT ATRIAL MYOCYTES [J].
BOYLE, WA ;
NERBONNE, JM .
AMERICAN JOURNAL OF PHYSIOLOGY, 1991, 260 (04) :H1236-H1247
[6]  
CHAISSON JL, 1981, J CLIN INVEST, V68, P706
[7]   EFFECT OF INSULIN ON KINETICS OF SUGAR-TRANSPORT IN HEART-MUSCLE [J].
CHEUNG, JY ;
CONOVER, C ;
REGEN, DM ;
WHITFIELD, CF ;
MORGAN, HE .
AMERICAN JOURNAL OF PHYSIOLOGY, 1978, 234 (01) :E70-E78
[8]   A REFINEMENT OF THE AKABAYASHI-SAITO-KATO MODIFICATION OF THE ENZYMATIC METHODS FOR 2-DEOXYGLUCOSE AND 2-DEOXYGLUCOSE 6-PHOSPHATE [J].
CHI, MMY ;
MANCHESTER, JK ;
CARTER, JG ;
PUSATERI, ME ;
MCDOUGAL, DB ;
LOWRY, OH .
ANALYTICAL BIOCHEMISTRY, 1993, 209 (02) :335-338
[9]   IMPROVED ENZYMATIC CYCLE FOR NICOTINAMIDE-ADENINE DINUCLEOTIDE PHOSPHATE [J].
CHI, MMY ;
LOWRY, CV ;
LOWRY, OH .
ANALYTICAL BIOCHEMISTRY, 1978, 89 (01) :119-129
[10]   INSULIN ACTION ON THE GLUCOSE-TRANSPORT SYSTEM IN ISOLATED CARDIOCYTES FROM ADULT-RAT [J].
ECKEL, J ;
PANDALIS, G ;
REINAUER, H .
BIOCHEMICAL JOURNAL, 1983, 212 (02) :385-392