Ion transport and electrophysiology in rabbit cecum.
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.
Clauss
W
W
Institut für Veterinärphysiologie, Freie Universität Berlin, Federal Republic of Germany.
Hoffmann
B
B
Schäfer
H
H
Hörnicke
H
H
D000818:Animals; D002432:Cecum / Q000502:physiology*; D004553:Electric Conductivity; D004594:Electrophysiology / Q000379:methods; D004848:Epithelium / Q000502:physiology; D066298:In Vitro Techniques; D007408:Intestinal Absorption; D007477:Ions; D007700:Kinetics; D008297:Male; D008433:Mathematics; D008564:Membrane Potentials; D008962:Models, Theoretical; D009130:Muscle, Smooth / Q000502:physiology; D011817:Rabbits; D012413:Rubidium / Q000378:metabolism*; D012964:Sodium / Q000378:metabolism*
D007477:Ions; D012964:Sodium; D012413:Rubidium