Active K transport across rabbit distal colon: relation to Na absorption and Cl secretion

Journal Article · Fri Aug 01 04:00:00 EDT 1986 · Am. J. Physiol.; (United States)

OSTI ID:6281072

Halm, D R; Frizzell, R A

The authors measured isotopic unidirectional fluxes of K to elucidate the mechanisms of active K transport across the distal colon of the rabbit. Separate pathways for active K absorption and active K secretion were detected using various transport inhibitors and stimulators. The rate and direction of net USK transport depend on the activities of these two pathways. K absorption was reduced by orthovanadate (both solutions) or serosal Ba, consistent with ATPase-dependent uptake of K across the apical membrane and exit via a Ba-sensitive basolateral K conductance. K secretion was inhibited by serosal ouabain or mucosal Ba, indicating that K secretion involves basolateral uptake via the Na-K pump and apical exit via a Ba-sensitive K conductance. Active K secretion appears to be electrogenic, since inhibition by ouabain produced equivalent changes in the net K flux and short-circuit current. Addition of bumetanide to the serosal solution or the removal of either Na or Cl from the serosal solution inhibited K secretion; mucosal solutions amiloride was without effect. These results indicate that this K secretory process is independent of electrogenic Na absorption but is mechanistically similar to TWCl secretory processes. Both epinephrine and prostaglandin E2 (PGE2) stimulate K secretion, but only PGE2 also stimulates Cl secretion. The response to these secretogogues suggest that the mechanisms underlying K and Cl secretion are closely linked but can be regulated independently.

• Research Organization: Univ. of Alabama, Birmingham
• OSTI ID: 6281072
• Journal Information: Am. J. Physiol.; (United States), Journal Name: Am. J. Physiol.; (United States) Vol. 251:2; ISSN AJPHA
• Country of Publication: United States
• Language: English

Related Subjects

551001* -- Physiological Systems-- Tracer Techniques
59 BASIC BIOLOGICAL SCIENCES
ABSORPTION
ACID ANHYDRASES
ALKALI METAL COMPOUNDS
ALKALI METAL ISOTOPES
ANIMALS
ATP-ASE
BETA DECAY RADIOISOTOPES
BETA-MINUS DECAY RADIOISOTOPES
BODY
CHLORINE 36
CHLORINE ISOTOPES
DIGESTIVE SYSTEM
ELECTRON CAPTURE RADIOISOTOPES
ENZYMES
GASTROINTESTINAL TRACT
HOURS LIVING RADIOISOTOPES
HYDROLASES
INTERMEDIATE MASS NUCLEI
INTESTINES
ISOTOPES
LARGE INTESTINE
LIGHT NUCLEI
MAMMALS
MEMBRANE TRANSPORT
NUCLEI
ODD-ODD NUCLEI
ORGANS
PHOSPHOHYDROLASES
PHYSIOLOGY
POTASSIUM 42
POTASSIUM COMPOUNDS
POTASSIUM ISOTOPES
RABBITS
RADIOISOTOPES
SECRETION
VERTEBRATES
YEARS LIVING RADIOISOTOPES