Abstract
A major function of the colon is the conservation of salt and water which may be aided by short chain fatty acids. The only previous studies of the mechanisms involved in infants have been in vivo where electrical gradients influence ionic movements. We have carried out a more detailed study of transport in isolated human infant colon using an Ussing Chamber and voltage clamp procedure. Stripped L side colonic mucosa (n=6 pairs) was mounted and bathed in Krebs solution. Under short circuit conditions Na+ (3.45±1.53 umol/hr/cm2mean ISD) and Cl− (0.63±3.61) were absorbed and a residual ion flux consistent with HCO3− secretion, approximates Cl− absorption. Short-circuit current (3.8±0.28) approximates net Na+ movement. 60 mM acetate increased Na+ absorption (3.45±1.53 to 7.74±2.25, p<0.05) by a large increase in mucosa to serosa flux (7.24±0.92 to 13.55±1.62, p<0.01). The increased net absorption of Na+ was markedly reduced by 10− M amiloride (7.74±2.25 to 1.75±1.72, p<0.01) which was also associated with a marked reduction in tissue conductance. These data clearly show that in the infant Na+ is absorbed electrogenically and Cl electroneutrally in exchange for HCO3− unlike in vivo where Cl− moves according to the electrical gradient. Short chain fatty acids favourably influence Na+ salvage and do so via the amiloride Na+ channel. Thus bacterial metabolism of carbohydrate in the infant colon may be important in the conservation of salt and water.
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Jenkins, H., Schnackenberg, U. & Milla, P. 6. MECHANISMS OF TRANSPORT OF SODIUM AND CHLORIDE AND THE EFFECTS OF SHORT CHAIN FATTY ACIDS IN THE HUMAN INFANT. Pediatr Res 22, 97 (1987). https://doi.org/10.1203/00006450-198707000-00027
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DOI: https://doi.org/10.1203/00006450-198707000-00027