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Regulation of glucose uptake in rat slow and fast skeletal muscles
Camp. Biochem. Physiol. Vol. 91A, No. 2, pp. 363-365, Printed in Great Britain
1988 0
0300-9629/88 $3.00 + 0.00 1988 Pcrgamon Press plc
REGULATION OF GLUCOSE UPTAKE IN RAT SLOW AND FAST SKELETAL MUSCLES SHIN’ICHI
SH~JI
Department of Medicine, Shinshu University School of Medicine, Matsumoto 390, Japan. Telephone: 0263 35-4600 (Received 2 February 1988) Abstract-l. Regulation of glucose uptake was compared between extensor digitorum longus (EDL) and soleus (Sol) muscles in rats. 2. Insulin stimulated glucose uptake more in EDL than in Sol. 3. Under high concentrations of insulin, the glucose uptake was higher in EDL than Sol. 4. Inhjbition of oxidative phosphorylation by anoxia or an uncoupler stimulated glucose uptake more in EDL than in Sol. 5. Anoxia abolished the effect of insulin on glucose uptake in both EDL and Sol. 6. The blocker to glucose transport system reduced glucose uptake more in Sol than in EDL.
There are many muscle diseases that show relatively selective involvement of one muscle type or muscle fibre type. To search for the cause of vulnerability of muscle or muscle fibre type is very important for the pathogenetic study of these diseases. Significant correlation between glucose transport
through plasma membrane and enzyme activities in carbohydrate metabolism of skeletal muscle has been reported (Byloud et al., 1976). Regulation at the step of glucose entry into muscle is believed to be the most important in the control of carbohydrate metabolism in muscle (Morgan et al., 1961). In order to compare the carbohydrate metabolism of fast and slow musdes under the effects of insulin, inhibition of oxidative phosphorylation, and inhibition of glucose transport system, 3-0-methylglucose uptake in EDL and Sol of Wistar rats was determined. The present study showed that the two muscles had different patterns of response to these factors.
MATERIALS
AND METHODS
glucose (I mM, l.O~Ci~ml), and a mixture of 14Clabeled and unlabeled sucrose (1 mM, 0.2@/ml). For anoxia experiment, 95% N,S% CO2 gas was used instead of a mixed gas of 0, and CO,. 3-0-methylglucose uptake was linear up to 60 min under these conditions. Radioactivity After 30min incubation the muscle was washed in icecold physiolo~~al saline. The tendons of the muscle were removed. The muscles were blotted, weighed, and digested in 0.4ml of Soluene 350 (Packard). After complete digestion, the digests were neutralized with acetic acid. The dual isotope radioactivity of the muscle digests and medium aliquots was determined in Scintisol EX-H (Wake) by a scintillation counter (Packard 3225) after one overnight storage in the counter. Calculations 3-0-methylglucose uptake was assessed as the difference between total 3-0-methylglucose space and sucrose space (extracellular space). For insulin experiments, uptake data were pooled for each concentration of insulin and significance of differences between means were determined by Student’s f-test, For other experiments, contralateraf muscles were used as controls. Analysis was done by Student’s f-test for paired observations.
Animals The rats used in this study were female Wistar rats weighing from 40 to 5Og. They could take water and rat chow ad libitum. Mu&es The animals were killed by head strike and cervical dislocation. Sol and EDL were excized with their proximal and distal tendons intact. Before resection, muscle with tendons was fixed with a holder at the length of the muscle in the stretched position in vivo, as described previously (Shoji, 1986a). The muscle was incubated in a flask with gentle shaking under continuous gassing of 95% 0,-S% Co, in an incubator at 37°C. The basic medium was Krebs-Henseleit bicarbonate buffer (PH 7.4), containing 5 mM sodium pyruvate, a mixture of )H-labeled and unlabeled 3-O-methyl-
RESULTS
Uptake of 3-O-methylglucose with and ~thout insulin in EDL and Sol are shown in Table 1. Uptake
without insulin (basal uptake) was greater in Sol than EDL. Insulin stimulated the uptake significantly when compared with basal uptake at concentrations from 10T3 to 10-l U/ml in both muscles. The uptake in Sol was greater than in EDL at con~ntrations up to 10-4U/ml, but this relationship reversed at lo-’ and 10-I U/ml. The uptake of 3-0-methylglucose increased significantly when the insulin concentration was increased IO-fold, from low4 to lo-’ and low3 to lo-* U/ml in EDL and only from 10V4to 10e3 U/ml in Sol. 363
SHIN’ICHI SHOJI
364
Table I. Effect of insulin on 3.0-methylglucose uptake in extensor digitorum longus and soleus muscles 3-0-methylglucose EDL
Insulin concentration Basal IO-*U/ml lo-’ 10-z 10-l
42.5 f 40.7 f 66.7 * 80.4 + 84.5 f
1.7 (31). 1.3 (22) 3.7 (6)t I” 4.6 (12)t In 6.7 (8)t
uptake SOI
53.4 * 2.2 56.1 + 2.1 73.2 f 6.3 697k5.1 7419 f 7.8
(318 (22)5 (6): (12)f$“’ (8)ts
*Mean k SEM, Unit = n mol/g wet weight/mitt at 37”C, 3-O-methylglucase = I mM, numbers in parentheses are number of muscles used. tf < 0.001 vs basal, $P < 0.01 vs basal, $P < 0.001 vs EDL, I/P < 0.01 between two groups, VP < 0.025 between two groups.
Anoxia Uptake of 3-0-methylglucose increased significantly only in EDL under anoxia (Table 2). 2,bDinitrophenol In both EDL and Sol, a significant increase in 3-0-methylglucose uptake was produced by 5 PM 2,4-dinitrophenol. Rates of increase were 52% in EDL and 25% in Sol (Table 2). Anoxia + insulin Anoxia abolished insulin’s stimulation effect on 3-0-methylglucose uptake both in EDL and Sol even with high concentrations of insulin (lo-‘, 10m2U/ml) (Table 2). Cytochalasin B Cytochalasin B inhibited 3-0-methylglucose uptake at a concentration of 1OOpM in both Sol and EDL (Table 2). Inhibitable uptakes were 16.0 and 11.Onmol/g wet weight/min in Sol and EDL, respectively. DISCUSSION
The present study used isolated muscles weighing less than 35 mg to overcome the diffusion problem. The isolated muscles did not receive a blood supply and innervation and were held in a stretched position. Holding in a stretched position enhanced glucose uptake (Shoji, 1986b). Even with limitations, this method is not complicated and is useful for comparison between muscles. The present data showed that the basal transport rate of 3-0-methylglucose through muscle membrane Table 2. 3-0-methylglucose Conditions Anaerobict 2,4-Dinitrophenolt 5yM Anaerobic, Insulint IO-’ U/ml IO-’ U/ml Cytochalasin Bt IOOpM l
uptake under various conditions 3-0-methylglucose EDL N 10
l19*7t§
uptake ratio* SOI
107 * 7
4
152* 1%
125+%
4 4
104*6 82 f 9
95*4 81 *7
6
65 f 5#
54*35
uptake of 3-0-methylglucose under the condition x 100 uptake of 3-0-methylglucose under the control condition
tControl condition was aerobic without drug or hormone and with a solvent for drug or hormone. N: number of muscle pairs for determinations. tSMean f SEM. $P < 0.05 compared to control of 100%.
in Sol was greater than in EDL, but under high concentrations of the hormone the rate in EDL became greater than that in Sol. There have been a few reports comparing the effects of insulin on glucose uptake in slow and fast muscles. Goodman et al. (1983) reported that 2-deoxyglucose uptake by Sol was greater than EDL at 2 x 10e4 U/ml of insulin using perfused rat hind quarter. Uptake of 2-deoxyglucose by isolated Sol and EDL of mice with and without insulin of various concentrations from 3 x 10m5 to 4 x 10m3U/ml was determined and uptake by Sol was greater (Bonen et al., 1981). Maximum stimulation by insulin of 2-deoxyglucose uptake was obtained at 3 x lo-’ U/ml in both Sol and EDL (Bonen et al., 1981). However, the present study showed the maximum stimulated uptake of 3-Omethylglucose to be at 10m3or lo-* U/ml among the examined range of concentrations in Sol and EDL, respectively. To my knowledge there have been three other studies of insulin-stimulated glucose uptake in isolated Sol of rat. The rates of maximum stimulated uptake by insulin to basal uptake were 2.3, 2.9, and 1.8 at 10m3,lo-‘, and 10-l U/ml of insulin concentration, respectively (Chaudry et al., 1970; Kohn et al., 1971, Clausen, 1975). The present results may be explained as follows. Under usual or physiological conditions or lower concentrations of insulin, slow muscle seems to need more glucose than fast muscle. When insulin concentration increased because of factors stimulating the secretion of endogenous insulin or administration of exogenous insulin, glucose uptake by slow muscle responds and quickly reaches saturation level, but glucose uptake by fast muscle increases more slowly and to a greater extent than that by slow muscle. Glucose uptake under anoxic or anaerobic conditions was examined and an increased uptake in Sol, diaphragm, and perfused heart was reported (Randle et al., 1958, Morgan et al., 1961, Chaudry et al., 1969). The present results showed a significant increase of uptake (+ 19%) only in EDL, as the increase in Sol (+7%) was not significant. In comparison, anaerobic condition has a greater effect more on fast muscle than on slow muscle. 2,CDinitrophenoL an uncoupler in oxidative phosphorylation, increased glucose uptake in diaphragm and Sol (Randle et al., 1958, Chaudry et al., 1969). The present study revealed that an uncoupler concentration of 5 PM significantly stimulated the uptake in EDL (+52%) and in Sol (+25%). The former increment was twice the latter.
Glucose uptake in rat muscle Anoxia and 2,4-dinitrophenol both inhibit oxidative phosphorylation and deplete ATP (Yu et al., 1978). ATP regulates the transport of glucose into the muscle cell by functioning as a feedback inhibitor (Randle et al., 1958). Diminishing this inhibition stimulates glucose uptake, and judging from the present results this stimulation seems to be greater in fast muscle than in slow. Insulin-stimulated glucose uptake by rat hemidiaphragm was suppressed by extended anaerobic incubation (Walaas et al., 1952); and anoxia stimulated insulin effect on glucose uptake in perfused heart (Morgan et al., 1961) and decreased insulin response on xylose uptake in isolated Sol (Yu et al., 1978). Response to insulin under anaerobic conditions is quite different in heart and skeletal muscle. The effect of insulin is now considered to be through translocation of the glucose transport system from the intracellular pool (microsomal storage) to plasma membrane (Wardzala et al., 1983) and this process needs ATP (Yu et al., 1978). Inhibition of oxidative phosphorylation, by anoxia or 2,4-dinitrophenol, reduces ATP, then inhibits translocation of the glucose transport system. Anoxia’s abolishment of response to insulin may be through this process. Therefore, anoxia or 2,4-dinitrophenol-stimulated glucose uptake should be through activation of the glucose transport system in the plasma membrane without changing its number. In isolated Sol the effect of insulin was to lower the K, of glucose uptake, while anoxia increased the I’,,,,, (Chaudry et al., 1969). This effect is stronger in fast muscle than in slow. These results indicate that in two types of skeletal muscles, glucose uptake and carbohydrate metabolism can be regulated differently. Acknowledgements-This work was supported by Grant No. 84-08 from the National Center for Nervous, Mental and Muscular Disorders (NCNMMD) of the Ministry of Health and Welfare, Japan. REFERENCES Bonen A., Tan M. H. and Watson-Wright W. H. (1981) Insulin binding and glucose uptake differences in rodent skeletal muscles. Diabetes 30, 702-704. Byloud A. C., Holms J., Lundholm K. and Scherstin T. (1976) Incorporation rate of glucose carbon, palmitate
365
carbon and leucine carbon into metabolites in relation to enzyme activities and RNA levels in human skeletal muscles. Enzyme 21, 39-52. Chaudry I. H. and Gould M. K. (1969) Kinetics of glucose uptake in isolated soleus muscle. Biochem. Biophys. Acta 177, 527-536. Chaudry I. H. and Gould M. K. (1970) Effect of externally added ATP on glucose uptake by isolated rat soleus muscle. Biochem. Biophys. Acta l%, 327-335. Clausen T. (1975) The effect of insulin on glucose transport in muscle cells. Curr. Top. Membr. Tramp. 6, 169-226. Goodman M. N., Dluz S. M., Mcelaney M. A., Belur E. and Ruderman N. B. (1983) Glucose uptake and insulin sensitivity in rat muscle: changes during 3-96 weeks of age. Am. J. Physiol. 244 (Endocrinol. Metab. 7), E93-EIOO. Kohn P. G. and Clausen T. (1971) The relationship between the transport of glucose and cations across cell membranes in isolated tissues. VI. The effect of insulin, ouabain, and metabolic inhibitors on the transport of 3-0-methylglucose and glucose in rat soleus muscles. Biochem. Biophys. Acta 225, 277-290. Morgan H. E., Henderson M. J., Regen D. M. and Park C. R. (1961) Regulation of glucose uptake in muscle. I. The effects of insulin and anoxia on glucose transport and phosphorylation in the isolated, perfused heart of normal rats. J. biol. Chem. 236, 253-261. Morgan H. E., Regen D. M., Henderson M. J., Sawyer T. K. and Park C. R. (1961) Regulation of glucose uptake in muscle. VI. Effects of hypophysectomy, adrenalectomy, growth hormone, hydrocortisone, and insulin on glucose transport and phosphorylation in the perfused rat heart. J. biol. Chem. 236, 2162-2168. Randle P. J. and Smith G. H. (1958) Regulation of glucose uptake by muscle. 2. The effects of insulin, anaerobiosis and cell poisons on the penetration of isolated rat diaphragm by sugars. Biochem. J. 70, 501-508. Shoji S. (1986a) Effect of denervation on glucose uptake in rat soleus and extensor digitorum longus muscles. Muscle Nerve 9, 69-72. Shoji S. (1986b) Effects of stretch and starvation on glucose uptake of rat soleus and extensor digitorum longus muscles. Muscle Nerve 9, 144147. Walaas E. and Walaas D. (1952) Effect of insulin on rat diaphragm under anaerobic conditions. J. biol. Chem. 195, 367-373. Wardxala L. J. and Jeanrenaud B. (1983) Identification of the o-glucose-inhibitable cytochalasin B binding site as the glucose transporter in rat diaphragm plasma and microsomal membranes. Biochem. Biophys. Acra 703, 49-56. Yu K. T. and Gould M. K. (1978) Permissive effect of ATP on insulin-stimulated sugar transport by rat soleus muscle. Am. J. Physiol. 234, E407-E416.
1988 0
0300-9629/88 $3.00 + 0.00 1988 Pcrgamon Press plc
REGULATION OF GLUCOSE UPTAKE IN RAT SLOW AND FAST SKELETAL MUSCLES SHIN’ICHI
SH~JI
Department of Medicine, Shinshu University School of Medicine, Matsumoto 390, Japan. Telephone: 0263 35-4600 (Received 2 February 1988) Abstract-l. Regulation of glucose uptake was compared between extensor digitorum longus (EDL) and soleus (Sol) muscles in rats. 2. Insulin stimulated glucose uptake more in EDL than in Sol. 3. Under high concentrations of insulin, the glucose uptake was higher in EDL than Sol. 4. Inhjbition of oxidative phosphorylation by anoxia or an uncoupler stimulated glucose uptake more in EDL than in Sol. 5. Anoxia abolished the effect of insulin on glucose uptake in both EDL and Sol. 6. The blocker to glucose transport system reduced glucose uptake more in Sol than in EDL.
There are many muscle diseases that show relatively selective involvement of one muscle type or muscle fibre type. To search for the cause of vulnerability of muscle or muscle fibre type is very important for the pathogenetic study of these diseases. Significant correlation between glucose transport
through plasma membrane and enzyme activities in carbohydrate metabolism of skeletal muscle has been reported (Byloud et al., 1976). Regulation at the step of glucose entry into muscle is believed to be the most important in the control of carbohydrate metabolism in muscle (Morgan et al., 1961). In order to compare the carbohydrate metabolism of fast and slow musdes under the effects of insulin, inhibition of oxidative phosphorylation, and inhibition of glucose transport system, 3-0-methylglucose uptake in EDL and Sol of Wistar rats was determined. The present study showed that the two muscles had different patterns of response to these factors.
MATERIALS
AND METHODS
glucose (I mM, l.O~Ci~ml), and a mixture of 14Clabeled and unlabeled sucrose (1 mM, 0.2@/ml). For anoxia experiment, 95% N,S% CO2 gas was used instead of a mixed gas of 0, and CO,. 3-0-methylglucose uptake was linear up to 60 min under these conditions. Radioactivity After 30min incubation the muscle was washed in icecold physiolo~~al saline. The tendons of the muscle were removed. The muscles were blotted, weighed, and digested in 0.4ml of Soluene 350 (Packard). After complete digestion, the digests were neutralized with acetic acid. The dual isotope radioactivity of the muscle digests and medium aliquots was determined in Scintisol EX-H (Wake) by a scintillation counter (Packard 3225) after one overnight storage in the counter. Calculations 3-0-methylglucose uptake was assessed as the difference between total 3-0-methylglucose space and sucrose space (extracellular space). For insulin experiments, uptake data were pooled for each concentration of insulin and significance of differences between means were determined by Student’s f-test, For other experiments, contralateraf muscles were used as controls. Analysis was done by Student’s f-test for paired observations.
Animals The rats used in this study were female Wistar rats weighing from 40 to 5Og. They could take water and rat chow ad libitum. Mu&es The animals were killed by head strike and cervical dislocation. Sol and EDL were excized with their proximal and distal tendons intact. Before resection, muscle with tendons was fixed with a holder at the length of the muscle in the stretched position in vivo, as described previously (Shoji, 1986a). The muscle was incubated in a flask with gentle shaking under continuous gassing of 95% 0,-S% Co, in an incubator at 37°C. The basic medium was Krebs-Henseleit bicarbonate buffer (PH 7.4), containing 5 mM sodium pyruvate, a mixture of )H-labeled and unlabeled 3-O-methyl-
RESULTS
Uptake of 3-O-methylglucose with and ~thout insulin in EDL and Sol are shown in Table 1. Uptake
without insulin (basal uptake) was greater in Sol than EDL. Insulin stimulated the uptake significantly when compared with basal uptake at concentrations from 10T3 to 10-l U/ml in both muscles. The uptake in Sol was greater than in EDL at con~ntrations up to 10-4U/ml, but this relationship reversed at lo-’ and 10-I U/ml. The uptake of 3-0-methylglucose increased significantly when the insulin concentration was increased IO-fold, from low4 to lo-’ and low3 to lo-* U/ml in EDL and only from 10V4to 10e3 U/ml in Sol. 363
SHIN’ICHI SHOJI
364
Table I. Effect of insulin on 3.0-methylglucose uptake in extensor digitorum longus and soleus muscles 3-0-methylglucose EDL
Insulin concentration Basal IO-*U/ml lo-’ 10-z 10-l
42.5 f 40.7 f 66.7 * 80.4 + 84.5 f
1.7 (31). 1.3 (22) 3.7 (6)t I” 4.6 (12)t In 6.7 (8)t
uptake SOI
53.4 * 2.2 56.1 + 2.1 73.2 f 6.3 697k5.1 7419 f 7.8
(318 (22)5 (6): (12)f$“’ (8)ts
*Mean k SEM, Unit = n mol/g wet weight/mitt at 37”C, 3-O-methylglucase = I mM, numbers in parentheses are number of muscles used. tf < 0.001 vs basal, $P < 0.01 vs basal, $P < 0.001 vs EDL, I/P < 0.01 between two groups, VP < 0.025 between two groups.
Anoxia Uptake of 3-0-methylglucose increased significantly only in EDL under anoxia (Table 2). 2,bDinitrophenol In both EDL and Sol, a significant increase in 3-0-methylglucose uptake was produced by 5 PM 2,4-dinitrophenol. Rates of increase were 52% in EDL and 25% in Sol (Table 2). Anoxia + insulin Anoxia abolished insulin’s stimulation effect on 3-0-methylglucose uptake both in EDL and Sol even with high concentrations of insulin (lo-‘, 10m2U/ml) (Table 2). Cytochalasin B Cytochalasin B inhibited 3-0-methylglucose uptake at a concentration of 1OOpM in both Sol and EDL (Table 2). Inhibitable uptakes were 16.0 and 11.Onmol/g wet weight/min in Sol and EDL, respectively. DISCUSSION
The present study used isolated muscles weighing less than 35 mg to overcome the diffusion problem. The isolated muscles did not receive a blood supply and innervation and were held in a stretched position. Holding in a stretched position enhanced glucose uptake (Shoji, 1986b). Even with limitations, this method is not complicated and is useful for comparison between muscles. The present data showed that the basal transport rate of 3-0-methylglucose through muscle membrane Table 2. 3-0-methylglucose Conditions Anaerobict 2,4-Dinitrophenolt 5yM Anaerobic, Insulint IO-’ U/ml IO-’ U/ml Cytochalasin Bt IOOpM l
uptake under various conditions 3-0-methylglucose EDL N 10
l19*7t§
uptake ratio* SOI
107 * 7
4
152* 1%
125+%
4 4
104*6 82 f 9
95*4 81 *7
6
65 f 5#
54*35
uptake of 3-0-methylglucose under the condition x 100 uptake of 3-0-methylglucose under the control condition
tControl condition was aerobic without drug or hormone and with a solvent for drug or hormone. N: number of muscle pairs for determinations. tSMean f SEM. $P < 0.05 compared to control of 100%.
in Sol was greater than in EDL, but under high concentrations of the hormone the rate in EDL became greater than that in Sol. There have been a few reports comparing the effects of insulin on glucose uptake in slow and fast muscles. Goodman et al. (1983) reported that 2-deoxyglucose uptake by Sol was greater than EDL at 2 x 10e4 U/ml of insulin using perfused rat hind quarter. Uptake of 2-deoxyglucose by isolated Sol and EDL of mice with and without insulin of various concentrations from 3 x 10m5 to 4 x 10m3U/ml was determined and uptake by Sol was greater (Bonen et al., 1981). Maximum stimulation by insulin of 2-deoxyglucose uptake was obtained at 3 x lo-’ U/ml in both Sol and EDL (Bonen et al., 1981). However, the present study showed the maximum stimulated uptake of 3-Omethylglucose to be at 10m3or lo-* U/ml among the examined range of concentrations in Sol and EDL, respectively. To my knowledge there have been three other studies of insulin-stimulated glucose uptake in isolated Sol of rat. The rates of maximum stimulated uptake by insulin to basal uptake were 2.3, 2.9, and 1.8 at 10m3,lo-‘, and 10-l U/ml of insulin concentration, respectively (Chaudry et al., 1970; Kohn et al., 1971, Clausen, 1975). The present results may be explained as follows. Under usual or physiological conditions or lower concentrations of insulin, slow muscle seems to need more glucose than fast muscle. When insulin concentration increased because of factors stimulating the secretion of endogenous insulin or administration of exogenous insulin, glucose uptake by slow muscle responds and quickly reaches saturation level, but glucose uptake by fast muscle increases more slowly and to a greater extent than that by slow muscle. Glucose uptake under anoxic or anaerobic conditions was examined and an increased uptake in Sol, diaphragm, and perfused heart was reported (Randle et al., 1958, Morgan et al., 1961, Chaudry et al., 1969). The present results showed a significant increase of uptake (+ 19%) only in EDL, as the increase in Sol (+7%) was not significant. In comparison, anaerobic condition has a greater effect more on fast muscle than on slow muscle. 2,CDinitrophenoL an uncoupler in oxidative phosphorylation, increased glucose uptake in diaphragm and Sol (Randle et al., 1958, Chaudry et al., 1969). The present study revealed that an uncoupler concentration of 5 PM significantly stimulated the uptake in EDL (+52%) and in Sol (+25%). The former increment was twice the latter.
Glucose uptake in rat muscle Anoxia and 2,4-dinitrophenol both inhibit oxidative phosphorylation and deplete ATP (Yu et al., 1978). ATP regulates the transport of glucose into the muscle cell by functioning as a feedback inhibitor (Randle et al., 1958). Diminishing this inhibition stimulates glucose uptake, and judging from the present results this stimulation seems to be greater in fast muscle than in slow. Insulin-stimulated glucose uptake by rat hemidiaphragm was suppressed by extended anaerobic incubation (Walaas et al., 1952); and anoxia stimulated insulin effect on glucose uptake in perfused heart (Morgan et al., 1961) and decreased insulin response on xylose uptake in isolated Sol (Yu et al., 1978). Response to insulin under anaerobic conditions is quite different in heart and skeletal muscle. The effect of insulin is now considered to be through translocation of the glucose transport system from the intracellular pool (microsomal storage) to plasma membrane (Wardzala et al., 1983) and this process needs ATP (Yu et al., 1978). Inhibition of oxidative phosphorylation, by anoxia or 2,4-dinitrophenol, reduces ATP, then inhibits translocation of the glucose transport system. Anoxia’s abolishment of response to insulin may be through this process. Therefore, anoxia or 2,4-dinitrophenol-stimulated glucose uptake should be through activation of the glucose transport system in the plasma membrane without changing its number. In isolated Sol the effect of insulin was to lower the K, of glucose uptake, while anoxia increased the I’,,,,, (Chaudry et al., 1969). This effect is stronger in fast muscle than in slow. These results indicate that in two types of skeletal muscles, glucose uptake and carbohydrate metabolism can be regulated differently. Acknowledgements-This work was supported by Grant No. 84-08 from the National Center for Nervous, Mental and Muscular Disorders (NCNMMD) of the Ministry of Health and Welfare, Japan. REFERENCES Bonen A., Tan M. H. and Watson-Wright W. H. (1981) Insulin binding and glucose uptake differences in rodent skeletal muscles. Diabetes 30, 702-704. Byloud A. C., Holms J., Lundholm K. and Scherstin T. (1976) Incorporation rate of glucose carbon, palmitate
365
carbon and leucine carbon into metabolites in relation to enzyme activities and RNA levels in human skeletal muscles. Enzyme 21, 39-52. Chaudry I. H. and Gould M. K. (1969) Kinetics of glucose uptake in isolated soleus muscle. Biochem. Biophys. Acta 177, 527-536. Chaudry I. H. and Gould M. K. (1970) Effect of externally added ATP on glucose uptake by isolated rat soleus muscle. Biochem. Biophys. Acta l%, 327-335. Clausen T. (1975) The effect of insulin on glucose transport in muscle cells. Curr. Top. Membr. Tramp. 6, 169-226. Goodman M. N., Dluz S. M., Mcelaney M. A., Belur E. and Ruderman N. B. (1983) Glucose uptake and insulin sensitivity in rat muscle: changes during 3-96 weeks of age. Am. J. Physiol. 244 (Endocrinol. Metab. 7), E93-EIOO. Kohn P. G. and Clausen T. (1971) The relationship between the transport of glucose and cations across cell membranes in isolated tissues. VI. The effect of insulin, ouabain, and metabolic inhibitors on the transport of 3-0-methylglucose and glucose in rat soleus muscles. Biochem. Biophys. Acta 225, 277-290. Morgan H. E., Henderson M. J., Regen D. M. and Park C. R. (1961) Regulation of glucose uptake in muscle. I. The effects of insulin and anoxia on glucose transport and phosphorylation in the isolated, perfused heart of normal rats. J. biol. Chem. 236, 253-261. Morgan H. E., Regen D. M., Henderson M. J., Sawyer T. K. and Park C. R. (1961) Regulation of glucose uptake in muscle. VI. Effects of hypophysectomy, adrenalectomy, growth hormone, hydrocortisone, and insulin on glucose transport and phosphorylation in the perfused rat heart. J. biol. Chem. 236, 2162-2168. Randle P. J. and Smith G. H. (1958) Regulation of glucose uptake by muscle. 2. The effects of insulin, anaerobiosis and cell poisons on the penetration of isolated rat diaphragm by sugars. Biochem. J. 70, 501-508. Shoji S. (1986a) Effect of denervation on glucose uptake in rat soleus and extensor digitorum longus muscles. Muscle Nerve 9, 69-72. Shoji S. (1986b) Effects of stretch and starvation on glucose uptake of rat soleus and extensor digitorum longus muscles. Muscle Nerve 9, 144147. Walaas E. and Walaas D. (1952) Effect of insulin on rat diaphragm under anaerobic conditions. J. biol. Chem. 195, 367-373. Wardxala L. J. and Jeanrenaud B. (1983) Identification of the o-glucose-inhibitable cytochalasin B binding site as the glucose transporter in rat diaphragm plasma and microsomal membranes. Biochem. Biophys. Acra 703, 49-56. Yu K. T. and Gould M. K. (1978) Permissive effect of ATP on insulin-stimulated sugar transport by rat soleus muscle. Am. J. Physiol. 234, E407-E416.