Increased glucose transfer in the rat jejunum after dietary potassium loading: effect of amiloride.
The glucose transfer across the jejunum was measured in Wistar rats under a high potassium diet (HKD). In 12 of 27 HKD animals the transfer coefficient for D-glucose was not significantly higher than in control ones, (7.38 +/- 0.88).10(-5) s-1. In the other 15 a clear increase in glucose transfer was observed, (23.31 +/- 2.50).10(-5) s-1. The D-glucose transfer in the first group (n = 12) was, as in the case of the control rats, insensitive to amiloride section (10(-4) M), while D-glucose transfer became sensitive to amiloride in the second group (mean inhibition 94 +/- 8%, n = 14). A smaller but significant increase in L-glucose and sucrose transfers was also observed when the D-glucose movement was increased. No differences in short-circuit current, transepithelial potential, resistance and mucosa to serosa Na+ fluxes were observed between control and HKD rats and no effects of amiloride (10(-4) M) on these parameters were observed either in control or in HKD animals. [3H]Glucose uptake as also performed in brush-border vesicles prepared from rat jejunum, under control and HKD conditions. The specific and Na(+)-dependent 'overshoot' in D-glucose concentration, in vesicles prepared from HKD rats, became sensitive to amiloride action (10(-5) M). It is concluded that, besides the cellular adaptation induced in the distal portion of the nephron and large intestine, dietary potassium loading induces important modifications in glucose transfer in the rat jejunum.
Capurro
C
C
Departamento de Fisiologia, Facultad de Medicina, Universidad de Buenos Aires, Argentina.
Dorr
R
R
Parisi
M
M
D000584:Amiloride / Q000494:pharmacology*; D000818:Animals; D004032:Diet; D004848:Epithelium / Q000187:drug effects / Q000378:metabolism / Q000502:physiology; D005947:Glucose / Q000378:metabolism*; D066298:In Vitro Techniques; D007536:Isomerism; D007583:Jejunum / Q000187:drug effects / Q000378:metabolism*; D007700:Kinetics; D008564:Membrane Potentials / Q000187:drug effects; D008871:Microvilli / Q000187:drug effects / Q000378:metabolism; D011188:Potassium / Q000008:administration & dosage / Q000494:pharmacology*; D051381:Rats; D011919:Rats, Inbred Strains; D012016:Reference Values; D012964:Sodium / Q000378:metabolism
D000584:Amiloride; D012964:Sodium; D005947:Glucose; D011188:Potassium