Carney S, Thompson L
Am J Physiol. 1981 Jan;240(1):F12-6. doi: 10.1152/ajprenal.1981.240.1.F12.
Renal clearance studies were performed on parathyroid-intact and acutely thyroparathyroidectomized (TPTX) rats to clarify calcitonin (CT) action on renal electrolyte transport. Although CT (0.15 U x 100 g body wt-1 x h-1) reduced fractional excretion of calcium and magnesium by 72 and 46%, respectively, in TPTX rats without altering sodium and phosphate excretion, a 10-fold increase in CT (1.5 U) caused a smaller reduction in calcium and magnesium excretion and significantly increased sodium and phosphate excretion. A higher CT dose (15 U) did not alter calcium excretion, increased magnesium excretion, and caused an even greater increase in sodium and phosphate excretion. Results in parathyroid-intact animals were similar. Despite the fall in plasma calcium following CT administration, the filtered calcium load was unaltered due to a concomitant increase in glomerular filtration rate. Calcium infusion prior to CT (0.15 U) prevented a detectable fall in plasma calcium concentration. However, a 45% fall in fractional calcium excretion occurred despite the significant increase in filtered calcium. These data suggest that the physiological role of calcitonin on the nephron is to conserve calcium. Reports of increased electrolyte excretion presumably reflect a depressant effect of pharmacological doses of CT on nephron function.
对甲状旁腺完整和急性甲状旁腺切除（TPTX）的大鼠进行了肾脏清除率研究，以阐明降钙素（CT）对肾脏电解质转运的作用。尽管在TPTX大鼠中，CT（0.15 U×100 g体重-1×h-1）分别使钙和镁的分数排泄减少了72%和46%，而不改变钠和磷酸盐的排泄，但CT剂量增加10倍（1.5 U）导致钙和镁排泄的减少幅度较小，并显著增加了钠和磷酸盐的排泄。更高的CT剂量（15 U）没有改变钙排泄，增加了镁排泄，并导致钠和磷酸盐排泄的进一步增加。甲状旁腺完整动物的结果相似。尽管给予CT后血浆钙下降，但由于肾小球滤过率同时增加，滤过钙负荷未改变。在给予CT（0.15 U）之前输注钙可防止血浆钙浓度出现可检测到的下降。然而，尽管滤过钙显著增加，但分数钙排泄仍下降了45%。这些数据表明，降钙素在肾单位上的生理作用是保存钙。关于电解质排泄增加的报道可能反映了药理剂量的CT对肾单位功能的抑制作用。
