Ion fluxes and electrical characteristics of the short-circuited rat colon in vitro.
The unidirectional fluxes of sodium and chloride across stripped rat colon mucosa were measured and compared with the electrical characteristics of the tissue under voltage-clamped conditions. The relationship between the serosal-mucosal fluxes of the two ions and an imposed potential revealed that the serosal-mucosal flux of sodium was entirely paracellular, whereas there was also a transcellular component of the corresponding chloride flux. In the absence of sodium, the short-circuit current and net chloride flux were abolished; in the absence of chloride, the net sodium flux was reduced but not abolished, and the short-circuit current was unchanged. From an analysis of the effects of the inhibitors, amiloride, theophylline, acetazolamide, furosemide and piretanide, a plausible model was developed to explain the characteristics of these transports. It was proposed that both membranes possess Cl-/HCO-3 antiports, though their sensitivities to inhibitors were different. There is also a Na+/Cl- symport and an electrogenic sodium entry mechanism in the brushborder membrane.
D000086:Acetazolamide / Q000494:pharmacology; D000818:Animals; D001692:Biological Transport; D002712:Chlorides / Q000378:metabolism*; D003106:Colon / Q000378:metabolism / Q000502:physiology*; D004553:Electric Conductivity; D004594:Electrophysiology; D005665:Furosemide / Q000494:pharmacology; D066298:In Vitro Techniques; D051381:Rats; D011919:Rats, Inbred Strains; D012964:Sodium / Q000378:metabolism*; D013449:Sulfonamides / Q000494:pharmacology; D013806:Theophylline / Q000494:pharmacology
D002712:Chlorides; D013449:Sulfonamides; D005665:Furosemide; D012964:Sodium; D013806:Theophylline; C015451:piretanide; D000086:Acetazolamide