ISSN:
1432-2013
Keywords:
Phosphate (Pi) transport
;
Isolated rat enterocytes
;
Calcitriol (1,25(OH)2 vitamin D3)
;
Vitamin D deficiency
;
Methyl esters of cisvaccinic acid and transvaccinic acid
Source:
Springer Online Journal Archives 1860-2000
Topics:
Medicine
Notes:
Abstract In the present work we studied rapid in vitro effects of calcitriol (1,25(OH)2 vitamin D3) on the intestinal transport of inorganic phosphate (Pi). Enterocytes from vitamin D replete (D+) as well as vitamin D depleted (D−) rats were isolated mechanically from the duodeno-jejunum. In this model, Pi uptake was a temperature and Na+-dependent phenomenon. The in vitro-addition of calcitriol (1 pM) resulted in a significant enhancement of initial Pi uptake rate by enterocytes from D+ (P〈0.01) and D− (P〈0.05) rats. This effect which was Na+-dependent, was observed within the time of 20 min, but not before. A similar effect on Pi uptake rates of D+ or D− enterocytes could be elicited by the in vitro addition of the methyl ester of cis-vaccinic acid (MCVA) which is thought to increase membrane fluidity by modifying the lipid composition of the cell membrane. The stimulatory effect of calcitriol on Pi uptake rate was blunted in the presence of the methyl ester of transvaccinic acid (MTVA) thought to decrease membrane fluidity. Enterocyte Pi efflux rate constant (o KPi) remained unchanged in the presence of calcitriol (1 pM). In conclusion, the study demonstrates a rapid in vitro effect of calcitriol on Pi uptake by isolated enterocytes from D+ and D− rats. It suggests, but does not prove, that the hormone may act via an action independent of genomic nuclear activation.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00584093
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