高钾对离体蛇肾小管中对氨基马尿酸（PAH）转运及通透性的影响。

High K+ effects on PAH transport and permeabilities in isolated snake renal tubules.

作者信息

Dantzler W H, Bentley S K

出版信息

Am J Physiol. 1975 Jul;229(1):191-9. doi: 10.1152/ajplegacy.1975.229.1.191.

DOI:10.1152/ajplegacy.1975.229.1.191

Abstract

Effects of high potassium concentrations on para-aminohippurate (PAH) transport by isolated, perfused snake (Thamnophis spp.) distal-proximal renal tubules were studied. Increasing the potassium concentration in bath from 3 mM TO 10 mM OR 40 MM led to about 50% decrease in net PAH transport from bath to lumen in less than 10 min, but transport still occurred against concentration gradient. Cell water PAH concentration was not significantly depressed in 10 mMpotassium and was nearly double control level in 40 mM potassium. Apparent luminal membrane permeability to PAH, calculated from perfusion studies, averaged about 3.5 x 10(-5) cm sec(-1) in 3 mM potassium, 1.15 x 10(-5) cm sec(-1) in 10 mM potassium, and 0.48 x 10(-5) cm sec(-1) in 40 mM potassium. Apparent peritubular membrane permeability, determined from PAH efflux from tubules with oil-filled lumens averaged about 0.5 x 10(-5) cm sec(-1) in 3 mM potassium, 0.29 x 10(-5) cm sec(-1) in 10 mM potassium, and 0.17 x 10(-5) cm sec(-1) in 40 mM potassium. These data suggest that high potassium concentrations depress transepithelial PAH transport primarily by reducing luminal and peritubular membrane permeabilities. Effect of high potassium on PAH transport was reversed within 20 min after restoration of control potassium concentration.

摘要

研究了高钾浓度对离体灌注蛇（束带蛇属）远端-近端肾小管对对氨基马尿酸（PAH）转运的影响。将浴液中的钾浓度从3 mM提高到10 mM或40 mM，导致在不到10分钟内，从浴液到管腔的PAH净转运量下降约50%，但转运仍逆浓度梯度发生。在10 mM钾溶液中，细胞内水相中PAH浓度没有显著降低，而在40 mM钾溶液中，该浓度几乎是对照水平的两倍。根据灌注研究计算，管腔膜对PAH的表观通透性在3 mM钾溶液中平均约为3.5×10⁻⁵ cm·sec⁻¹，在10 mM钾溶液中为1.15×10⁻⁵ cm·sec⁻¹，在40 mM钾溶液中为0.48×10⁻⁵ cm·sec⁻¹。从充满油的管腔的肾小管中PAH流出量测定的管周膜表观通透性在3 mM钾溶液中平均约为0.5×10⁻⁵ cm·sec⁻¹，在10 mM钾溶液中为0.29×10⁻⁵ cm·sec⁻¹，在40 mM钾溶液中为0.17×10⁻⁵ cm·sec⁻¹。这些数据表明，高钾浓度主要通过降低管腔膜和管周膜的通透性来抑制PAH的跨上皮转运。恢复对照钾浓度后20分钟内，高钾对PAH转运的影响逆转。