Li J H, Palmer L G, Edelman I S, Lindemann B
J Membr Biol. 1982;64(1-2):77-89. doi: 10.1007/BF01870770.
Urinary bladders of Bufo marinus were depolarized, by raising the serosal K concentration, to facilitate voltage-clamping of the apical membrane. Passive Na transport across the apical membrane was then studied with near-instantaneous current-voltage curves obtained before and after eliciting a natriferic response with oxytocin. Fitting with the constant-field equation showed that the natriferic effect is accounted for by an increase in the apical Na permeability. It is accompanied by a small increase in cellular Na activity. Furthermore, fluctuation analysis of the amiloride-induced shot-noise component of the short-circuit current indicated that the permeability increase is not due to increased Na translocation through those Na channels which were already conducting prior to hormonal stimulation. Rather, the natriferic effects is found to be based on an increase in the population of transporting channels. It appears that, in response to the hormone, Na channels are rapidly "recruited" from a pool of electrically silent channels.
通过提高浆膜钾离子浓度使海蟾蜍的膀胱去极化，以利于对顶端膜进行电压钳制。然后，利用催产素引发排钠反应前后获得的近瞬时电流-电压曲线，研究了顶端膜上钠的被动转运。用常数场方程拟合表明，排钠效应是由顶端钠通透性增加引起的。它伴随着细胞内钠活性的小幅增加。此外，对短路电流的氨氯地平诱导散粒噪声成分的波动分析表明，通透性增加并非由于通过激素刺激前就已传导的那些钠通道的钠转运增加。相反，发现排钠效应是基于转运通道数量的增加。似乎在激素作用下，钠通道迅速从一群电沉默通道中“募集”而来。
