title: Effects of bovine somatotropin and insulin on whole-body and hindlimb glucose metabolism in growing steers.
abstract: Six Holstein steers (245 kg initial BW) were surgically prepared with chronic catheters to allow measurement of blood flow and nutrient flux across the hindlimb. Steers were used in a single-reversal design with 16-d treatment periods of daily i.m. injection of either excipient (control) or recombinantly derived bovine somatotropin (120 micrograms/kg BW). On d 15 of each period, whole-body and hindlimb glucose metabolism were studied during a primed continuous infusion of [6(-3)H]glucose, under both basal conditions and during a hyperinsulinemic/euglycemic clamp. Somatotropin increased (P < .01) basal blood glucose and serum insulin by 7 and 150% respectively, with no change in glucose irreversible loss rate (ILR). There was no effect of somatotropin on hindlimb blood flow or oxygen consumption. In contrast, hindlimb lactate uptake (P < .02) and the ratio of glucose to oxygen uptake (P < .08) were reduced by somatotropin. Insulin infusion stimulated (P < .01) glucose ILR and inhibited (P < .02) endogenous glucose production to a lesser extent during somatotropin treatment. Basal plasma nonesterified fatty acid concentrations were increased (P < .01) during somatotropin treatment and decreased (P < .02) during insulin infusion. Insulin infusion increased hindlimb blood flow and glucose uptake to similar extents during both treatment periods. These data demonstrate that somatotropin treatment of growing steers decreases response of tissues to insulin (sensitivity in muscle, sensitivity, and responsiveness in liver and adipose tissue), thereby increasing glucose availability to other tissues.
authors.affiliation: Department of Animal Science, Cornell University, Ithaca, NY 14853, USA.
authors.forename: F R
authors.initials: FR
authors.lastname: Dunshea
authors.forename: Y R
authors.initials: YR
authors.lastname: Boisclair
authors.forename: D E
authors.initials: DE
authors.lastname: Bauman
authors.forename: A W
authors.initials: AW
authors.lastname: Bell
mesh_terms: D000273:Adipose Tissue / Q000378:metabolism; D000818:Animals; D001786:Blood Glucose / Q000032:analysis; D002417:Cattle / Q000254:growth & development / Q000378:metabolism* / Q000502:physiology; D018592:Cross-Over Studies; D005230:Fatty Acids, Nonesterified / Q000097:blood; D005947:Glucose / Q000378:metabolism*; D015309:Glucose Clamp Technique; D013006:Growth Hormone / Q000494:pharmacology*; D006614:Hindlimb / Q000098:blood supply; D007004:Hypoglycemic Agents / Q000494:pharmacology*; D007328:Insulin / Q000097:blood / Q000494:pharmacology*; D007333:Insulin Resistance / Q000502:physiology; D007773:Lactates / Q000378:metabolism; D008099:Liver / Q000378:metabolism; D008297:Male; D018482:Muscle, Skeletal / Q000098:blood supply / Q000378:metabolism* / Q000502:physiology; D010101:Oxygen Consumption / Q000502:physiology; D012039:Regional Blood Flow; D013997:Time Factors; D014316:Tritium
chemical_list: D001786:Blood Glucose; D005230:Fatty Acids, Nonesterified; D007004:Hypoglycemic Agents; D007328:Insulin; D007773:Lactates; D014316:Tritium; D013006:Growth Hormone; D005947:Glucose