Shareghi G R, Agus Z S
Am J Physiol. 1982 Apr;242(4):F379-84. doi: 10.1152/ajprenal.1982.242.4.F379.
The mode and mechanism of phosphate transport in the light portion of the rabbit cortical collecting duct were studied with isolated tubular perfusion. Control studies (n = 48) revealed a mean transepithelial potential difference (PD) of -16.5 +/- 1.3 mV and net phosphate absorption (JPO4) of 0.58 +/- 0.07 pmol.mm-1.min-1. To characterize transport, the effects of flow rate, ouabain, amiloride, and phosphate concentration, and parathyroid hormone (PTH) were analyzed. There was a significant linear relationship between JPO4 and flow rate (n = 48) (r = 0.71, P less than 0.025). Increasing the difference between lumen and bath phosphate concentration from -8.0 to +8.0 mg/dl was associated with a stepwise increase in JPO4 from -0.18 +/- 0.02 to 0.93 +/- 0.05 pmol.mm-1.min-1. PTH had no effect on JPO4. To assess the effects of PD, the tubules were treated with either amiloride (n = 6) or ouabain (n = 7). JPO4 fell significant in both circumstances with reduction of PD, although there remained significant residual transport following amiloride addition. The data demonstrate significant phosphate transport in this segment that is independent of PTH and altered by transepithelial electrical and concentration gradients as well as flow rate.
采用离体肾小管灌注法研究了兔皮质集合管光镜部分磷酸盐转运的方式和机制。对照研究（n = 48）显示跨上皮电位差（PD）平均为-16.5±1.3 mV，净磷酸盐吸收（JPO4）为0.58±0.07 pmol·mm⁻¹·min⁻¹。为了表征转运情况，分析了流速、哇巴因、氨氯吡咪、磷酸盐浓度和甲状旁腺激素（PTH）的影响。JPO4与流速之间存在显著的线性关系（n = 48）（r = 0.71，P＜0.025）。将管腔与浴槽中磷酸盐浓度的差值从-8.0增加到+8.0 mg/dl，JPO4随之从-0.18±0.02逐步增加到0.93±0.05 pmol·mm⁻¹·min⁻¹。PTH对JPO4无影响。为评估PD的作用，分别用氨氯吡咪（n = 6）或哇巴因（n = 7）处理肾小管。在两种情况下，随着PD降低，JPO4均显著下降，不过添加氨氯吡咪后仍存在显著的残余转运。数据表明该节段存在显著的磷酸盐转运，其独立于PTH，并受跨上皮电和浓度梯度以及流速的影响而改变。
