title: Growth hormone directly stimulates gluconeogenesis in canine renal proximal tubule.
abstract: To characterize the action of growth hormone (GH) on gluconeogenesis in renal proximal tubule, glucose production was measured in suspensions of canine renal proximal tubular segments incubated with 1 mM L-alanine, 10 mM lactate, 1 mM succinate, and various concentrations (10(-11) to 10(-6) M) of recombinant bovine GH (bGH). Production of glucose increased as a function of time for 120 min. Bovine growth hormone (10(-6) M) increased glucose production at 120 min by 55 +/- 16%. Significant enhancement of glucose production occurred in suspensions of segments incubated with as little as 10(-10) M bGH. Half-maximal stimulation occurred at between 10(-9) and 10(-8) M. To ascertain whether these actions of bGH are mediated directly, we determined the effects of insulin-like growth factors (IGFs) I and II on glucose production. Addition of IGF-I to segments enhanced glucose production in a concentration-dependent manner. However, incubation with bGH did not induce measurable IGF-I production in the segments. In contrast to the action of IGF-I, IGF-II did not affect glucose production. We conclude that bGH acts directly on cells within proximal tubular segments to enhance gluconeogenesis. Stimulation of gluconeogenesis in vitro could reflect a counterregulatory action of GH exerted on renal proximal tubule in vivo.
authors.affiliation: Department of Internal Medicine, Washington University School of Medicine, St. Louis, Missouri 63110.
authors.forename: S A
authors.initials: SA
authors.lastname: Rogers
authors.forename: I E
authors.initials: IE
authors.lastname: Karl
authors.forename: M R
authors.initials: MR
authors.lastname: Hammerman
mesh_terms: D000818:Animals; D004285:Dogs; D005943:Gluconeogenesis / Q000187:drug effects*; D005947:Glucose / Q000096:biosynthesis; D013006:Growth Hormone / Q000494:pharmacology*; D066298:In Vitro Techniques; D007334:Insulin-Like Growth Factor I / Q000494:pharmacology; D007335:Insulin-Like Growth Factor II / Q000494:pharmacology; D007687:Kidney Tubules, Proximal / Q000378:metabolism*; D009994:Osmolar Concentration; D011863:Radioimmunoassay; D013268:Stimulation, Chemical
chemical_list: D007334:Insulin-Like Growth Factor I; D007335:Insulin-Like Growth Factor II; D013006:Growth Hormone; D005947:Glucose