K+ transport by rat colon: adaptation to a low potassium diet

Journal Article · Sat Mar 01 04:00:00 EST 1986 · Am. J. Physiol.; (United States)

OSTI ID:5617582

Tannen, R L; Marino, R; Dawson, D C

Recent studies with the isolated perfused rat kidney have demonstrated the existence of an intrinsic renal adaptation to conserve K+ in response to ingestion of a low K+ diet for 3 days. To determine whether the colon alters its K+ transport properties in a similar fashion, we measured transmural 86Rb fluxes across sheets of distal colonic epithelium under short-circuit conditions. Preliminary studies using a double-isotope technique demonstrated that 86Rb and 42K fluxes were similar; therefore 86Rb flux was considered equivalent to K+ flux. The distal half of the colon from each rat was divided into two segments, referred to as early and late distal colon. Experiments were carried out using rats fed a K+ -free, control (0.15 mmol/g), and high K+ (1.13 mmol/g) powdered diet of otherwise identical electrolyte content. Net K+ secretion (Jnet) by the early distal colon was reduced from 0.45 in the controls to -0.02 mueq X cm-2 X h-1 by a low K+ diet as a result of a decrease in serosal-to-mucosal flux (Jsm), with no change in mucosal-to-serosal flux (Jms). Conductance (GT) and short-circuit current (Isc) were unchanged. Jnet by the late distal colon averaged 0.17 in the controls and 0.01 mueq X cm-2 X h-1 with a low K+ diet, but this difference was not significant statistically. In comparison with the controls, a high K+ diet had no effect on Jnet by the early distal colon (0.48 mueq X cm-2 X h-1) but increased Jnet by the late distal colon substantially (0.77 mueq X cm-2 X h-1).

• Research Organization: Univ. of Michigan, Ann Arbor
• OSTI ID: 5617582
• Journal Information: Am. J. Physiol.; (United States), Journal Name: Am. J. Physiol.; (United States); ISSN AJPHA
• Country of Publication: United States
• Language: English

Related Subjects

551001* -- Physiological Systems-- Tracer Techniques
59 BASIC BIOLOGICAL SCIENCES
ALKALI METAL ISOTOPES
ALKALI METALS
ANIMAL TISSUES
ANIMALS
BETA DECAY RADIOISOTOPES
BETA-MINUS DECAY RADIOISOTOPES
BODY
DAYS LIVING RADIOISOTOPES
DIET
DIGESTIVE SYSTEM
DOUBLE LABELLING
ELECTROPHYSIOLOGY
ELEMENTS
EPITHELIUM
GASTROINTESTINAL TRACT
HOURS LIVING RADIOISOTOPES
INTERMEDIATE MASS NUCLEI
INTESTINES
ISOMERIC TRANSITION ISOTOPES
ISOTOPES
LABELLING
LARGE INTESTINE
MAMMALS
MEMBRANE TRANSPORT
METALS
MINUTES LIVING RADIOISOTOPES
NUCLEI
ODD-ODD NUCLEI
ORGANS
PHYSIOLOGY
POTASSIUM
POTASSIUM 42
POTASSIUM ISOTOPES
RADIOISOTOPES
RATS
RODENTS
RUBIDIUM 86
RUBIDIUM ISOTOPES
TISSUES
VERTEBRATES