AJP - Gastrointestinal and Liver Physiology, Vol 256, Issue 6 1090-G1099, Copyright © 1989 by American Physiological Society

ARTICLES

Ion transport and electrophysiology in rabbit cecum

W. Clauss, B. Hoffmann, H. Schafer and H. Hornicke
Institut fur Veterinarphysiologie, Freie Universitat Berlin, Federal Republic of Germany.

We investigated the basic bioelectrical properties and the transport of Na+, Rb+, and Cl- in the isolated cecal epithelium of the rabbit. Intracellular microelectrode recordings provided first estimates of the individual membrane potentials and resistances. The cecal epithelium was found to be a moderately tight epithelium with a high transepithelial potential and a relative high paracellular resistance. It has, however, a low transepithelial resistance caused by a high rate of transcellular ion transport and a high transcellular conductance. Under short-circuit conditions Na+ and Cl- are absorbed, whereas Rb+ is secreted. Na+ absorption seems to be mediated via an electrogenic mechanism with low amiloride sensitivity and is partially linked to Cl- transport. Cl- absorption is not influenced by secretagogues, and Rb+ secretion occurs via a transcellular route. A basolateral K+ conductance was also found. The results show rabbit cecum as an epithelium with a high electrolyte transport capacity, distinctly different from the neighboring proximal colon, and suited to absorb the large quantities of electrolytes that are present in the luminal liquid.

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