TY - JOUR
T1 - Absence of Calcitriol-Mediated Nongenomic Actions in Isolated Intestinal Cells of the Damara Mole-Rat (Cryptomys damarensis)
AU - Buffenstein, R.
AU - Sergeev, I. N.
AU - Pettifor, J. M.
PY - 1994/7
Y1 - 1994/7
N2 - Calcitriol [1,25(OH)2D3] actions on intestinal calcium transport involve genomic and nongenomic pathways. Whether nongenomic 1,25(OH)2D3-mediated actions are employed was investigated using isolated intestinal epithelial cells of naturally vitamin D-deficient underground-dwelling damara mole-rats (Cryptomys damarensis). 1,25(OH)2D3-mediated nongenomic pathways of intestinal calcium uptake, measured by opening of 1,25(OH)2D3-activated voltage-sensitive Ca2+ channels (VSCC), did not occur. Rapid (1 min) 45Ca2+ transmembrane influx in intestinal cells was not significantly increased by the addition of 1,25(OH)2D3 (at concentrations from 10-12 to 10-6 nM), when compared to opening of VSCC in the presence of a depolarizing (elevated K+) buffer. Furthermore, even after 30 min calcium uptake was not significantly enhanced by the hormone. These findings support earlier reports that duodenal calcium absorption is independent of vitamin D and is a highly adaptive feature of a subterranean existence.
AB - Calcitriol [1,25(OH)2D3] actions on intestinal calcium transport involve genomic and nongenomic pathways. Whether nongenomic 1,25(OH)2D3-mediated actions are employed was investigated using isolated intestinal epithelial cells of naturally vitamin D-deficient underground-dwelling damara mole-rats (Cryptomys damarensis). 1,25(OH)2D3-mediated nongenomic pathways of intestinal calcium uptake, measured by opening of 1,25(OH)2D3-activated voltage-sensitive Ca2+ channels (VSCC), did not occur. Rapid (1 min) 45Ca2+ transmembrane influx in intestinal cells was not significantly increased by the addition of 1,25(OH)2D3 (at concentrations from 10-12 to 10-6 nM), when compared to opening of VSCC in the presence of a depolarizing (elevated K+) buffer. Furthermore, even after 30 min calcium uptake was not significantly enhanced by the hormone. These findings support earlier reports that duodenal calcium absorption is independent of vitamin D and is a highly adaptive feature of a subterranean existence.
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U2 - 10.1006/gcen.1994.1098
DO - 10.1006/gcen.1994.1098
M3 - Article
C2 - 7926652
AN - SCOPUS:0028240461
VL - 95
SP - 25
EP - 30
JO - General and Comparative Endocrinology
JF - General and Comparative Endocrinology
SN - 0016-6480
IS - 1
ER -