Cardinal J, Duchesneau D
Am J Physiol. 1978 May;234(5):F381-5. doi: 10.1152/ajprenal.1978.234.5.F381.
In order to study the effect of potassium on the renal tubule, proximal convoluted tubules were dissected from rabbit kidneys and perfused in vitro. Omitting potassium from both the perfusate and bath caused the rate of fluid absorption and the transtubular potential difference to fall to zero. This effect was due to the absence of potassium in the bathing medium since no change was observed when potassium was omitted from the perfusate only. With 0.5 and 1.0 meq/liter of potassium in the bath, there was still a significant decrease from control in both the potential difference and the rate of fluid absorption. With 2.5 meq/liter of potassium in the bath, the results did not differ from control. In further studies, tubules were perfused with 10 meq/liter of potassium in both perfusate and bath. There was no change in the potential difference of fluid absorption. These results are consistent with the view that active transtubular transport of sodium is linked to the influx of potassium into the cell at the peritubular membrane and that this is probably mediated by sodium-potassium-ATPase. Our results also suggest that the variations of potassium concentration in the physiological range do not affect proximal tubular function.
为了研究钾对肾小管的作用，从兔肾中分离出近端曲管并进行体外灌注。灌注液和浴液中均不含钾会导致液体吸收速率和跨管电位差降至零。这种效应是由于浴液中缺乏钾所致，因为仅在灌注液中省略钾时未观察到变化。当浴液中钾的浓度为0.5和1.0毫当量/升时，电位差和液体吸收速率仍较对照有显著降低。当浴液中钾的浓度为2.5毫当量/升时，结果与对照无差异。在进一步的研究中，向灌注液和浴液中均灌注10毫当量/升的钾。液体吸收的电位差没有变化。这些结果与以下观点一致，即钠的主动跨管转运与钾在肾小管周围膜处流入细胞有关，并且这可能由钠钾ATP酶介导。我们的结果还表明，生理范围内钾浓度的变化不会影响近端小管功能。
