title: Relative effects of systemic pH, PCO2, and HCO3 concentration on colonic ion transport.
abstract: To determine the relative effects of systemic pH, PCO2, and bicarbonate concentration on colonic electrolyte transport, states of acute metabolic acidosis and alkalosis were created in Sprague-Dawley rats by gavage feeding (NH4)2SO4 and NaHCO3, respectively. During in situ perfusion of the distal colon in pentobarbital-anesthetized animals, electrolyte transport was measured before and after respiratory compensation of the systemic pH. Acute respiratory acidosis and alkalosis also were studied by ventilating animals with 0, 3, or 8% CO2. When animals in all groups were considered, net sodium absorption correlated well with blood PCO2 (r = 0.99) but not with blood pH. Net bicarbonate secretion correlated with the plasma (r = 0.95) and luminal (r = -0.63) bicarbonate concentrations but not with blood pH or PCO2. Net chloride absorption correlated with both blood PCO2 (r = 0.92) and the plasma bicarbonate concentration (r = 0.80). These results suggest that systemic PCO2 affects a sodium chloride absorptive process and that the plasma bicarbonate concentration affects a chloride absorptive-bicarbonate secretory exchange process in the rat colon.
mesh_terms: D000138:Acidosis / Q000503:physiopathology*; D000471:Alkalosis / Q000503:physiopathology*; D000818:Animals; D001639:Bicarbonates / Q000378:metabolism*; D001693:Biological Transport, Active; D002245:Carbon Dioxide / Q000097:blood; D003106:Colon / Q000502:physiology*; D006863:Hydrogen-Ion Concentration; D007408:Intestinal Absorption; D007473:Ion Channels / Q000378:metabolism; D008297:Male; D010477:Perfusion; D051381:Rats; D011919:Rats, Inbred Strains; D012965:Sodium Chloride / Q000378:metabolism; D014882:Water-Electrolyte Balance
chemical_list: D001639:Bicarbonates; D007473:Ion Channels; D002245:Carbon Dioxide; D012965:Sodium Chloride