TY - JOUR
T1 - Passive uptake in the small intestine and active uptake in the hindgut contribute to the highly efficient mineral metabolism of the common mole-rat. cryptomys hottentotus
AU - Pitcher, Tammy
AU - Buffenstein, Rochelle
PY - 1994/4
Y1 - 1994/4
N2 - Cryptomys hottentotus has no access to dietary or endogenous sources of cholecalciferol (D3). Serum concentrations of calcifediol (25(OH)D3) were undetectable (5 ng/ml) and calcitriol (l,25(OH)2D3), although detectable in plasma, was at a low concentration (31.40 (sem 3.06 pg/ml). Despite their naturally impoverished vitamin D status, these animals exhibited highly efficient mineral absorption processes (Ca apparent fractional absorption efficiency, AFA (%) 9533 (sem 1.36); inorganic P (Pi) AFA (%) 93.49 (sem 0.81)). Furthermore, plasma mineral content was tightly regulated (Ca 2 57 (sem 0.08) mmol/1; Mg 1.23 (sem 0.05) mmol/1; Pi 2–12 (sem 0.15) mmol/1). Mode of uptake in C. hottentotus was unlike that in other D3-replete mammals. First, passive (rather than active) uptake occurred in the traditional site of active Ca absorption (with serosal:mucosal (S:M) ratios in the duodenum of 1.32 (sem 0.13)), and the only site of active Ca uptake was the hindgut (caecum S :M 3.35 (sem 0.46); proximal colon S: M 2.13(sem 0.30)). Despite the presence of active uptake in these hindgut regions, their overall contribution to the daily rate of mineral absorption was small (9.53 (sem 1.27) %). These underground inhabitants rely upon highly efficient, passive mineral uptake. This is adequate to meet their mineral requirements and maintain mineral homeostasis in the absence of vitamin D.
AB - Cryptomys hottentotus has no access to dietary or endogenous sources of cholecalciferol (D3). Serum concentrations of calcifediol (25(OH)D3) were undetectable (5 ng/ml) and calcitriol (l,25(OH)2D3), although detectable in plasma, was at a low concentration (31.40 (sem 3.06 pg/ml). Despite their naturally impoverished vitamin D status, these animals exhibited highly efficient mineral absorption processes (Ca apparent fractional absorption efficiency, AFA (%) 9533 (sem 1.36); inorganic P (Pi) AFA (%) 93.49 (sem 0.81)). Furthermore, plasma mineral content was tightly regulated (Ca 2 57 (sem 0.08) mmol/1; Mg 1.23 (sem 0.05) mmol/1; Pi 2–12 (sem 0.15) mmol/1). Mode of uptake in C. hottentotus was unlike that in other D3-replete mammals. First, passive (rather than active) uptake occurred in the traditional site of active Ca absorption (with serosal:mucosal (S:M) ratios in the duodenum of 1.32 (sem 0.13)), and the only site of active Ca uptake was the hindgut (caecum S :M 3.35 (sem 0.46); proximal colon S: M 2.13(sem 0.30)). Despite the presence of active uptake in these hindgut regions, their overall contribution to the daily rate of mineral absorption was small (9.53 (sem 1.27) %). These underground inhabitants rely upon highly efficient, passive mineral uptake. This is adequate to meet their mineral requirements and maintain mineral homeostasis in the absence of vitamin D.
KW - Calcium: Mole-rat
KW - Mineral metabolism
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U2 - 10.1079/BJN19940164
DO - 10.1079/BJN19940164
M3 - Article
C2 - 8011610
AN - SCOPUS:0028328220
VL - 71
SP - 573
EP - 582
JO - British Journal of Nutrition
JF - British Journal of Nutrition
SN - 0007-1145
IS - 4
ER -