가토 근위세뇨관에서 Percoll gradient에 의해 분리한 기저막소포(basolateral membrane vesicle)에서 PAH 이동에 미치는 여러 음이온들의 영향을 rapid filtration technique을 이용하여 관찰하였다. NA-dependent PAH 축적은 용액내 SO<sub>4</sub>와 SSO<sub>3</sub>에 의하여 유의하게 억제되었으나 Cl, SCN, HPO<sub>4</sub>, acetate 및 oxalate에 의해서는 영향을 받지 않았다. 용액내의 SO<sub>4</sub>는 상경적으로 PHA 이동을 억제하였다. 소포내 음이온을 부하시킨 후 PAH 이동을 측정했을 때 acetate, SO<sub>4</sub> 및 PAH의 부하에 의해 PAH 이동은 유의하게 증가되었으며, 소포내 부하되는 SO<sub>4</sub>농도가 증가함에 따라 PAH 축적은 증가되었다. SO<sub>4</sub>에 의한 PAH의 trans-stimulation은 Na 농도 경사 존재시 더욱 증가되었으며 이들은 2 mM probenecid 및 1mM SITS에 의해 억제되었다. 이들 결과들은 신피질세뇨관 세포의 기저막에 PAH/음이온 교환에 의해 PAH가 이동되는 기전이 존재한다는 것을 가르킨다. 그러나 PAH 이동에 영향이 없는 음이온들은 PAH/음이온 교환에 기질로써 작용하지 않기 때문인지 아니면 이들 음이온들의 높은 투과성에 인해 나타난 결과인지는 더욱 추구해 보아야 확인될 것으로 생각된다.
Effects of anions on p-Aminohippurate (PAH) transport across the basolateral membrane (BLM) were studied. Basolateral membrane vesicles were isolated from rabbit renal cortex by using a self-orienting Percoll-gradient centrifugation and Mg<sup>2+</sup>-precipitation. The characteristics of the membrane vesicles was examined by marker enzyme activity, membrane orientation and transport studies. The Na-K-ATPase activity in the fraction containing BLM vesicles was enriched 9¡¤fold, and the alkaline phosphatase activity in the fraction containing BBM vesicles was increased 9-fold, compared with those of the homogenate. The transport properties of the two membrane preparations were studied by a rapid filtration technique. The uptake of PAH by BLM was sensitive to changes in medium osmolarity and inhibited by probenecid. When the uptake of 50μM PAH in voltage-clamped BLM vesicles was determined in the presence of various anions in the incubation medium, cis inhibitions by SO<sub>4</sub> and SSO<sub>3</sub> were observed in the presence of sodium gradient (out>in). Sodium-dependent PAH uptake was inhibited competitively by external SO<sub>4</sub> PAH uptake in BLM vesicles loaded with 20 mM acetate and SO<sub>4</sub> or 200 μM PAH was significantly stimulated as compared with unloaded vesicles. The extent of trans-stmulation of PAH uptake by SO<sub>4</sub>. was increased with the inside concentration of SO<sub>4</sub>. This trans-stimulatory effect by SO<sub>4</sub>, was observed to be additive in the presence of Na gradient and completely inhibited by 2 mM probenecid and 1 mM SITS. These results demonstrate that PAH/anion exchange is present in BLM of renal cortex and in this exchange mechanism inorganic as well as organic anions are involved as substrates.
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