Kalu D N, Hadji-Georgopoulos A, Foster G V
J Endocrinol. 1975 Feb;64(2):299-304. doi: 10.1677/joe.0.0640299.
This study was designed to investigate the roles of bone and kidney in the acute regulation of plasma calcium by parathyroid hormone (PTH) during prolonged calcium deprivation. The effect of PTH was assessed by gland ablation. Animals were thyroparathyroidectomized or sham-operated and their urine was collected for 3 h. Subsequently they were anaesthetized and bled from the abdominal aorta. In rats fed on a low calcium diet, urinary hydroxyproline excretion was enhanced and, unlike animals fed on a normal diet, decreased 3 h after thyroparathyroidectomy (TPTX). In addition TPTX decreased plasma calcium by 0-45 mg/100 ml in normal rats compared with 1-94 mg/100 ml in animals fed on a calcium-deficient diet. Urinary calcium increased by 161 and 12 mug and accounted for 82 and 1-4 % of the fall in plasma calcium in normal and calcium-deprived animals respectively. The corresponding contributions of bone were 18 and 98-6%. These findings support the view that with prolonged calcium deprivation in adult rats, the relative contributions of bone and kidney to the acute regulation of the plasma calcium level by PTH are reversed. As a result, bone rather than kidney becomes the more important organ. At the same time non-PTH-mediated kidney reabsorption of calcium is increased.
本研究旨在探讨在长期钙缺乏期间，甲状旁腺激素（PTH）对骨骼和肾脏在急性调节血浆钙水平方面所起的作用。通过腺体切除来评估PTH的作用。对动物进行甲状腺甲状旁腺切除术或假手术，并收集其3小时的尿液。随后将它们麻醉并从腹主动脉取血。在喂食低钙饮食的大鼠中，尿羟脯氨酸排泄增加，并且与喂食正常饮食的动物不同，甲状腺甲状旁腺切除术后（TPTX）3小时尿羟脯氨酸排泄减少。此外，与喂食缺钙饮食的动物相比，TPTX使正常大鼠的血浆钙降低0 - 45mg/100ml，而使喂食缺钙饮食的动物血浆钙降低1 - 94mg/100ml。正常动物和缺钙动物的尿钙分别增加161和12μg，分别占血浆钙下降量的82%和1.4%。骨骼的相应贡献率分别为18%和98.6%。这些发现支持以下观点：在成年大鼠长期钙缺乏的情况下，骨骼和肾脏对PTH急性调节血浆钙水平的相对贡献发生了逆转。结果，骨骼而非肾脏成为更重要的器官。同时，非PTH介导的肾脏对钙的重吸收增加。
