Effect of vitamin D depletion on calcium transport by the luminal and basolateral membranes of the proximal and distal nephrons.
Endocrinology
; 132(1): 115-20, 1993 Jan.
Article
em En
| MEDLINE
| ID: mdl-8419116
ABSTRACT
To study the effect of vitamin D on calcium (Ca2+) reabsorption by the kidney, we measured Ca2+ uptake by the basolateral and luminal membranes of proximal and distal tubules obtained from rabbits fed a vitamin D-deficient diet for 3 weeks. Results were compared to those obtained with a group of control animals fed a normal diet. Serum Ca2+ concentrations were comparable in both groups. In the control group, serum PTH, 25-hydroxyvitamin D3, and 1,25-dihydroxyvitamin D3 remained relatively stable. In the vitamin D-deficient animals, serum PTH levels slightly, but not significantly, increased, and the levels of vitamin D metabolites abruptly fell. Vitamin D depletion produced a 40% decrease in ATP-dependent Ca2+ uptake by the basolateral membrane of the distal tubule. There was no change in the activity of the Na+/Ca2+ exchanger. A very significant effect was also observed in the luminal membrane of the distal tubule, where a 50% decrease in Ca2+ uptake was observed after the third week of vitamin depletion. Administration of 0.1 microgram 1,25-dihydroxyvitamin D3 16 and 2 h before death partially reestablished normal uptake. In contrast, no change in Ca2+ uptake could be detected in the basolateral or luminal membranes of the proximal tubule. These observations provide the first evidence of an effect of vitamin D on Ca2+ transport at both the basolateral and luminal membranes of the distal segment of the nephron.
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Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Deficiência de Vitamina D
/
Cálcio
/
Túbulos Renais Distais
/
Túbulos Renais Proximais
/
Néfrons
Limite:
Animals
Idioma:
En
Revista:
Endocrinology
Ano de publicação:
1993
Tipo de documento:
Article
País de afiliação:
Canadá