Peraino R A, Suki W N
Am J Physiol. 1980 May;238(5):F358-62. doi: 10.1152/ajprenal.1980.238.5.F358.
Renal handling of phosphate occurs in the proximal convoluted tubule. Absorption of this anion also occurs in the pars recta and distal convoluted tubule, the latter a structurally and functionally diverse segment. The purpose of the present investigation was to examine phosphate transport by the cortical collecting duct of the rabbit. Segments of cortical collecting tubule, beyond the last cortical branch, were isolated and perfused in vitro with an artificial solution simulating plasma as the perfusing and bathing medium. The perfusion solution contained either 3 or 25 mM bicarbonate. Net phosphate transport was measured using 32P as the radionuclide tracer, with identical specific activity in perfusing and bathing solutions. A net absorptive flux for phosphate was demonstrated, amounting to 2-3% of the delivered load. In addition, this absorptive flux was linearly related to perfusion rate and, thus, delivered load, but independent of the lumen bicarbonate concentration or pH.
肾脏对磷酸盐的处理发生在近端曲管。这种阴离子的吸收也发生在直部和远端曲管，后者是一个结构和功能多样的节段。本研究的目的是检测家兔皮质集合管对磷酸盐的转运。在最后一个皮质分支之外的皮质集合小管节段被分离出来，并在体外用人造溶液进行灌注，该溶液模拟血浆作为灌注和浴液介质。灌注液含有3或25 mM的碳酸氢盐。使用32P作为放射性核素示踪剂测量净磷酸盐转运，灌注液和浴液中的比活相同。结果表明存在磷酸盐的净吸收通量，相当于输送负荷的2-3%。此外，这种吸收通量与灌注速率呈线性相关，因此也与输送负荷呈线性相关，但与管腔碳酸氢盐浓度或pH无关。
