Intestinal absorption of manganese in experimental malnutrition.
We investigated possible changes in mechanisms of the intestinal absorption of Mn in rats malnourished with a low protein-low energy diet (M) for 4 weeks against controls fed a complete diet (C) during the same period. The absorption of Mn in the absence or in the presence of two small molecular weight ligands, citrate and L-histidine, was studied by an in vivo procedure. In both M and C rats, jejunal Mn absorption decreased linearly with time and was enhanced by the presence of the low molecular weight ligands. The initial rate of absorption, for Mn alone, was higher in M than in C rats, but it was indistinguishable between both groups in the presence of either citrate or L-histidine. Total Mn absorption, in midperfusion, was greater in M than in C animals with no ligands in the solutions (means +/- SEM, M = 2,969 +/- 923 vs. C = 654 +/- 218 pmol/cm, p less than 0.05). However, in the presence of citrate or L-histidine, the well-nourished rats absorbed more Mn than M rats. Also, water fluxes across the mucosa had a positive correlation with Mn transport when the ligands were present. This solvent drag of the trace element was not operant in the absence of citrate or L-histidine. These data indicate that the jejunal mucosa of M rats absorbs Mn more effectively than C animals, independently from water fluxes and the presence of small molecular weight chelators. These substances do not alter the uptake of Mn in growth-retarded rats, while they enhance the absorption of the trace metal in well-fed animals.
D000818:Animals; D002951:Citrates / Q000378:metabolism; D019343:Citric Acid; D002149:Energy Intake; D006639:Histidine / Q000378:metabolism; D007408:Intestinal Absorption; D007413:Intestinal Mucosa / Q000378:metabolism; D007583:Jejunum / Q000378:metabolism; D008297:Male; D008345:Manganese / Q000378:metabolism*; D011502:Protein-Energy Malnutrition / Q000378:metabolism*; D051381:Rats; D011919:Rats, Inbred Strains; D014882:Water-Electrolyte Balance
D002951:Citrates; D019343:Citric Acid; D008345:Manganese; D006639:Histidine