AJP - Endocrinology and Metabolism, Vol 265, Issue 6 E874-E879, Copyright © 1993 by American Physiological Society

ARTICLES

Growth hormone-enhanced acid production and glutamate and glutamine utilization in LLC-PK-F+ cells

T. C. Welbourne and J. Fuseler
Department of Physiology, Louisiana State University Medical Center, Shreveport 71130.

Growth hormone (GH), recombinant human (rh) GH, effects on transepithelial proton gradient, acid production, and glutamine (Gln) and glutamate (Glu-) utilization were studied in LLC-PK-F+ cells. Monolayers were incubated in Dulbecco's modified Eagle's media containing either 2 mM Gln or Glu- and 5 mM glucose plus 10% fetal bovine serum for 4 h, after which samples were taken for metabolite and acid-base parameter measurements. Monolayers grown on porous supports in Glu- media responded to 32 nM rhGH by decreasing Glu- net uptake 29% (470 +/- 135 to 336 +/- 98 nmol/4 h, P < 0.05), reflecting elimination of basolateral uptake (189 +/- 80 to 2 +/- 35 nmol/4 h, P < 0.05) as ammonium production decreased. In 2 mM Gln, rhGH decreased Gln net uptake 84% (1,096 +/- 215 to 155 +/- 150 nmol/4 h, P < 0.05), with basolateral uptake reversing to release; Glu- formation increased as ammonium production decreased. Monolayers grown on porous supports required rhGH to generate a transepithelial proton gradient within 4 h (0.01 +/- 0.05 control vs. 0.27 +/- 0.11 U for rhGH, P < 0.05); in addition, rhGH increased acid production (16.7 +/- 2.0 to 21.5 +/- 0.6 mumol x 4 h-1 x mg protein-1, P < 0.05). Adding insulin-like growth factor I (IGF-I) to the basolateral media decreased pH and enhanced Glu- and Gln uptake from that compartment.(ABSTRACT TRUNCATED AT 250 WORDS)

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