Bourdeau J E, Langman C B, Bouillon R
Kidney Int. 1987 Apr;31(4):913-7. doi: 10.1038/ki.1987.85.
Cortical thick ascending limbs of Henle's loop were dissected from the kidneys of chronically vitamin D-deficient or -replete rabbits and perfused in vitro. Unidirectional transepithelial calcium fluxes from lumen to bath were measured with 45Ca. The tubules were bathed in a solution containing 150 mM sodium and perfused with a solution containing 60 mM sodium to simulate conditions in the cortical thick ascending limb in vivo. Transepithelial voltages were equal across tubules from vitamin D-deficient and -replete rabbits. Likewise, baseline and parathyroid hormone-stimulated calcium fluxes were the same in tubules from the two groups. Because calcidiol and calcitriol were undetectable in the serum of the vitamin D-deficient rabbits, we suggest that neither of these endogenous vitamin D metabolites is essential in the regulation of calcium absorption in this portion of the rabbit nephron.
从长期缺乏维生素D或补充充足维生素D的兔子肾脏中分离出亨氏袢皮质厚升支，并进行体外灌注。用45Ca测量从管腔到浴液的单向跨上皮钙通量。肾小管浸泡在含有150 mM钠的溶液中，并用含有60 mM钠的溶液进行灌注，以模拟体内皮质厚升支的情况。缺乏维生素D和补充充足维生素D的兔子的肾小管跨上皮电压相等。同样，两组肾小管的基线和甲状旁腺激素刺激的钙通量相同。由于在缺乏维生素D的兔子血清中检测不到骨化二醇和骨化三醇，我们认为这两种内源性维生素D代谢产物对兔肾单位这一部分的钙吸收调节都不是必需的。
