Knox F G, Lechene C
Am J Physiol. 1975 Dec;229(6):1556-60. doi: 10.1152/ajplegacy.1975.229.6.1556.
The sites of inhibited phosphate transport following administration of bovine parathyroid hormone (bPTH) to thyroparathyroidectomized (TPTX) dogs were investigated. Phosphate reabsorption by the proximal and distal nephron was studied using recollection micropuncture, stop-flow methodology, and electron-probe microanalysis. Following bPTH, delivery of phosphate from the proximal tubule increased from 26 to 37% of the filtered load, P less than .01. Fractional phosphate excretion increased from 2.3 +/- 1.5 to 21.4 +/- 2.3%, P less than .001. The increased delivery of phosphate at the point of micropuncture in the proximal tubule accounted for approximately half of the phosphaturia. In six TPTX dogs, which were saline loaded, similiar increases in phosphate delivery from the proximal tubule from 27 +/- 1 to 36 +/- 2% of the filtered load resulted in a strikingly smaller phosphaturia, 5.1 +/- 1 to 9.8 +/- 2.4%, NS. In stop-flow experiments, phosphate concentratin ratios were slightly increased in the proximal nephron and markedly increased in the distal nephron following bPTH. It is concluded that parathyroid hormone markedly decreases phosphate transport in the distal nephron.
研究了给甲状腺甲状旁腺切除（TPTX）的犬注射牛甲状旁腺激素（bPTH）后磷酸盐转运受抑制的部位。使用回收微穿刺、停流方法和电子探针微量分析研究了近端和远端肾单位对磷酸盐的重吸收。注射bPTH后，近端小管中磷酸盐的输送量从滤过负荷的26%增加到37%，P＜0.01。磷酸盐排泄分数从2.3±1.5%增加到21.4±2.3%，P＜0.001。近端小管微穿刺点处磷酸盐输送量的增加约占磷尿症的一半。在6只接受生理盐水负荷的TPTX犬中，近端小管中磷酸盐输送量从滤过负荷的27±1%类似地增加到36±2%，但导致的磷尿症明显较小，为5.1±1%至9.8±2.4%，无统计学意义。在停流实验中，注射bPTH后，近端肾单位中的磷酸盐浓度比略有增加，而远端肾单位中的磷酸盐浓度比显著增加。结论是甲状旁腺激素显著降低远端肾单位中的磷酸盐转运。
