Stio M, Iantomasi T, Marraccini P, Vincenzini M T, Treves C
Department of Biochemical Sciences, University of Florence, Italy.
Biochem Int. 1991 Aug;24(6):1155-63.
We had previously reported that feeding rats on Steenbock and Black's rickets-inducing diet markedly influences the metabolic picture of the kidney and the transmembrane transport systems of D-glucose and citrate in renal brush-border membrane vesicles. We have now studied D-glucose and citrate transport into basolateral membrane vesicles prepared from kidney cortex of control and rachitic rats and the effect of 1,25-dihydroxyvitamin D3 on these transport systems was also investigated. D-glucose and citrate uptake, determined in the presence of a Na(+)-gradient, was lowered in rachitic animals and 1,25-dihydroxyvitamin D3 administration proved to be ineffective in restoring normal values. Citrate transport, determined in the presence of a K(+)-gradient, was not influenced by both rickets and 1,25-dihydroxyvitamin D3 supply. The in vitro addition to vesicle preparations of calcium or phosphate or citrate or 1,25-dihydroxyvitamin D3 did not show a selective influence on D-glucose and citrate uptake.
我们之前曾报道，用斯廷博克和布莱克的致佝偻病饮食喂养大鼠，会显著影响肾脏的代谢情况以及肾刷状缘膜囊泡中D-葡萄糖和柠檬酸的跨膜转运系统。我们现在研究了D-葡萄糖和柠檬酸向由对照大鼠和佝偻病大鼠肾皮质制备的基底外侧膜囊泡中的转运情况，并且还研究了1,25-二羟基维生素D3对这些转运系统的影响。在存在Na(+)梯度的情况下测定的D-葡萄糖和柠檬酸摄取量在佝偻病动物中降低，并且事实证明给予1,25-二羟基维生素D3对恢复正常值无效。在存在K(+)梯度的情况下测定的柠檬酸转运不受佝偻病和1,25-二羟基维生素D3供应的影响。在囊泡制剂中体外添加钙、磷酸盐、柠檬酸或1,25-二羟基维生素D3对D-葡萄糖和柠檬酸摄取没有显示出选择性影响。
