Basal and insulin-stimulated skeletal muscle sugar transport in endotoxic and bacteremic rats.
Membrane glucose transport with and without insulin was studied in soleus muscle from 5-h endotoxic rats (40 mg/kg Salmonella enteritidis lipopolysaccharide), and in soleus and epitrochlearis muscles from 12-h bacteremic (Escherichia coli, 4 X 10(10) CFU/kg) rats. Glucose transport was measured in muscles by evaluating the fractional efflux of 14C-labeled 3-O-methylglucose (14C-3-MG) after "loading" muscles with 14C-3-MG. Basal 3-MG transport was elevated in soleus muscles from endotoxic as well as in soleus and epitrochlearis muscles from bacteremic rats compared with time-matched controls. Low insulin concentrations stimulated 14C-3-MG transport more in bacteremic and endotoxic rat muscles than in controls. However, sugar transport in the presence of high insulin dose was attenuated in soleus and epitrochlearis muscles from bacteremic rats and soleus muscles from endotoxic rats compared with controls. Analysis of the dose-response relationship with ALLFIT revealed that the maximal transport response to insulin was significantly decreased in both models of septic shock. Sensitivity to insulin (EC50) was increased in endotoxic rat muscles, and a somewhat similar tendency was observed in bacteremic rat soleus muscles. Neural and humoral influences and/or changes in cellular metabolic energy may contribute to the increase in basal transport. Shifts in insulin-mediated transport may be due to alterations in insulin-receptor-effector coupling and/or the number of available glucose transporters.
Westfall
M V
MV
Department of Physiology, Loyola University Stritch School of Medicine, Maywood, Illinois 60153.
Sayeed
M M
MM
D019325:3-O-Methylglucose; D000818:Animals; D002250:Carbon Radioisotopes; D002462:Cell Membrane / Q000378:metabolism; D004927:Escherichia coli Infections / Q000378:metabolism*; D007328:Insulin / Q000494:pharmacology*; D007700:Kinetics; D008297:Male; D008757:Methylglucosides / Q000378:metabolism*; D008759:Methylglycosides / Q000378:metabolism*; D009132:Muscles / Q000187:drug effects / Q000378:metabolism*; D051381:Rats; D018805:Sepsis / Q000378:metabolism*; D014115:Toxemia / Q000378:metabolism*
D002250:Carbon Radioisotopes; D007328:Insulin; D008757:Methylglucosides; D008759:Methylglycosides; D019325:3-O-Methylglucose