Mercier O, Bichara M, Paillard M, Prigent A
Am J Physiol. 1986 Nov;251(5 Pt 2):F802-9. doi: 10.1152/ajprenal.1986.251.5.F802.
Urine-minus-blood PCO2 (U - B PCO2) during alkaline diuresis (urinary pH greater than 7.8) was determined in paired experiments using bicarbonate-loaded rats to assess the effects of parathyroid hormone (PTH) and urinary phosphate concentration [( Pi]u) on collecting duct H+ secretion. U-B PCO2 was higher for any value of urinary bicarbonate concentration ([HCO3]u) in the presence of PTH [intact rats and thyroparathyroidectomized (TPTX) PTH-infused rats] than in its absence (calcium-infused intact rats and TPTX rats). However, when [Pi]u was maintained constant by prior phosphate infusion, PTH administration in TPTX rats failed to elevate U-B PCO2. When PTH was infused in TPTX rats to maintain constant the plasma PTH level, subsequent phosphate infusion increased [Pi]u and elevated U-B PCO2 for any value of [HCO3]u. Moreover, when the data were pooled, there was a positive linear relationship between U-B PCO2 factored for [HCO3]u and [Pi]u (P less than 0.001). In all experiments, other factors that may affect U-B PCO2, such as plasma acid-base status, urinary osmolality, and extracellular fluid volume, did not vary. We conclude that PTH stimulates collecting duct H+ secretion indirectly via the increase in [Pi]u.
在使用碳酸氢盐负荷大鼠的配对实验中，测定了碱性利尿（尿液pH大于7.8）期间的尿减血PCO₂（U - B PCO₂），以评估甲状旁腺激素（PTH）和尿磷酸盐浓度[（Pi）u]对集合管H⁺分泌的影响。在存在PTH的情况下[完整大鼠和甲状旁腺切除（TPTX）并注入PTH的大鼠]，对于任何尿碳酸氢盐浓度（[HCO₃]u）值，U - B PCO₂均高于不存在PTH的情况（注入钙的完整大鼠和TPTX大鼠）。然而，当通过预先注入磷酸盐使（Pi）u保持恒定时，在TPTX大鼠中给予PTH未能提高U - B PCO₂。当在TPTX大鼠中注入PTH以维持血浆PTH水平恒定时，随后注入磷酸盐会增加（Pi）u，并使任何[HCO₃]u值的U - B PCO₂升高。此外，当汇总数据时，针对[HCO₃]u和（Pi）u进行因子校正后的U - B PCO₂之间存在正线性关系（P小于0.001）。在所有实验中，其他可能影响U - B PCO₂的因素，如血浆酸碱状态、尿渗透压和细胞外液量，均未发生变化。我们得出结论，PTH通过增加（Pi）u间接刺激集合管H⁺分泌。
