title: Integration of glucose transport with metabolic and functional activity of heart muscle.
abstract: The role of glucose transport modulation in adjusting myocardial energy supply to changing contractile and metabolic activity and to hormonal influences was studied. Because membrane transport is a rate-limiting step in glucose utilization, many physiological and pharmacological influences act at this step. These include muscular contraction, insulin, adrenaline, inotropic interventions. Na+ pump activity alterations, some heavy metal ions, and other Ca2+ antagonists. All these agents affect the sarcolemmal fluxes and/or the intracellular distribution of Ca2+, and the evidence is consistent with their effects on sugar transport being linked to their ability to alter the availability of cytoplasmic Ca2+. This is the basis for the hypothesis that sugar transport in muscle is regulated by Ca2+ binding to specific regulatory sites. Two positive controls, through contraction and insulin, and two negative feedbacks from mitochondrial oxidation and activity of the Na+ pump are identified.
mesh_terms: D000818:Animals; D002118:Calcium / Q000378:metabolism; D004837:Epinephrine / Q000494:pharmacology; D005947:Glucose / Q000378:metabolism*; D006168:Guinea Pigs; D006339:Heart Rate; D066298:In Vitro Techniques; D007328:Insulin / Q000494:pharmacology; D008660:Metabolism / Q000187:drug effects; D009200:Myocardial Contraction / Q000187:drug effects; D009206:Myocardium / Q000378:metabolism*; D010042:Ouabain / Q000494:pharmacology; D051381:Rats; D012964:Sodium / Q000378:metabolism
chemical_list: D007328:Insulin; D010042:Ouabain; D012964:Sodium; D005947:Glucose; D002118:Calcium; D004837:Epinephrine