2000
Effects of Caffeine on Muscle Glycogen Utilization and the Neuroendocrine Axis during Exercise1
Laurent D, Schneider K, Prusaczyk W, Franklin C, Vogel S, Krssak M, Petersen K, Goforth H, Shulman G. Effects of Caffeine on Muscle Glycogen Utilization and the Neuroendocrine Axis during Exercise1. The Journal Of Clinical Endocrinology & Metabolism 2000, 85: 2170-2175. PMID: 10852448, DOI: 10.1210/jcem.85.6.6655.Peer-Reviewed Original ResearchConceptsMuscle glycogen contentMuscle glycogen utilizationGlycogen contentCaffeine ingestionNeuroendocrine axisGlycogen utilizationGlycogen-sparing effectFree fatty acid concentrationsBeta-endorphin levelsCaffeine-treated groupExercise-induced glycogen depletionMaximal oxygen consumptionEffects of caffeineHigher muscle glycogen contentPlacebo groupExercise enduranceFatty acid concentrationsPlasma concentrationsNeuroendocrine hormonesCortisol releaseProlonged exerciseGlycogen depletionPlasma lactateNormal valuesThigh musclesMechanism of muscle glycogen autoregulation in humans
Laurent D, Hundal R, Dresner A, Price T, Vogel S, Petersen K, Shulman G. Mechanism of muscle glycogen autoregulation in humans. AJP Endocrinology And Metabolism 2000, 278: e663-e668. PMID: 10751200, DOI: 10.1152/ajpendo.2000.278.4.e663.Peer-Reviewed Original ResearchConceptsInsulin-stimulated ratesWhole body glucose oxidation ratesMuscle glycogenGlycogen loadingPlasma free fatty acid concentrationsWhole-body glucose uptakeFree fatty acid concentrationsMuscle glycogen contentGlucose oxidation ratesMuscle glycogen synthesisPlasma lactate concentrationTwofold increaseHyperinsulinemic clampGlycogen synthase activityFatty acid concentrationsLoading protocolGlucose infusionHealthy volunteersLactate concentrationGlycogen contentGlucose uptakeAnaerobic glycolysisGlycogen synthesisUnlabeled glucose infusionGlycogen
1999
Effects of free fatty acids on glucose transport and IRS-1–associated phosphatidylinositol 3-kinase activity
Dresner A, Laurent D, Marcucci M, Griffin M, Dufour S, Cline G, Slezak L, Andersen D, Hundal R, Rothman D, Petersen K, Shulman G. Effects of free fatty acids on glucose transport and IRS-1–associated phosphatidylinositol 3-kinase activity. Journal Of Clinical Investigation 1999, 103: 253-259. PMID: 9916137, PMCID: PMC407880, DOI: 10.1172/jci5001.Peer-Reviewed Original ResearchMeSH KeywordsAdolescentAdultFatty Acids, NonesterifiedFemaleGlucoseGlucose Clamp TechniqueGlucose-6-PhosphateGlycerolGlycogenHumansHyperinsulinismInsulinInsulin Receptor Substrate ProteinsInsulin ResistanceLipid MetabolismMagnetic Resonance SpectroscopyMaleMuscle, SkeletalPhosphatidylinositol 3-KinasesPhosphoproteinsConceptsFree fatty acidsIRS-1-associated phosphatidylinositolLipid infusionInsulin resistanceGlycerol infusionPlasma free fatty acidsWhole-body glucose uptakeFive-hour infusionLipid/heparinHyperinsulinemic-euglycemic clampGlucose concentrationGlucose transportMuscle glycogen synthesisDiminished glucose transportMuscle biopsy samplesHuman skeletal muscleRate of insulinGlucose-6-phosphate concentrationFatty acidsHealthy subjectsBiopsy samplesInfusion studiesIdentical protocolInfusionIRS-1-associated PI
1998
Effect of epinephrine on muscle glycogenolysis and insulin-stimulated muscle glycogen synthesis in humans
Laurent D, Petersen K, Russell R, Cline G, Shulman G. Effect of epinephrine on muscle glycogenolysis and insulin-stimulated muscle glycogen synthesis in humans. American Journal Of Physiology 1998, 274: e130-e138. PMID: 9458758, DOI: 10.1152/ajpendo.1998.274.1.e130.Peer-Reviewed Original ResearchConceptsInsulin-stimulated muscle glycogen synthesisMuscle glycogen synthesisMuscle glycogenolysisEpinephrine infusionPhysiological increaseWhole-body glucose oxidationMuscle glycogen synthesis ratesPlasma epinephrine concentrationEuglycemic hyperinsulinemic clampGlucose infusion rateEffect of epinephrineGlycogen synthesisInsulin-stimulated glycogenesisBasal insulinControl subjectsPlasma glucoseEpinephrine concentrationsFree fatty acidsBasal valuesInfusion rateGlycogen synthesis rateMuscle glycogenEpinephrineGlycogenolysisMajor impairment