关于离体虹鳟鱼鳃中铵根离子和钠离子通量的相互作用

On the interaction of NH+4 and Na+ fluxes in the isolated trout gill.

Kerstetter T H, Keeler M

J Exp Biol. 1976 Apr;64(2):517-27. doi: 10.1242/jeb.64.2.517.

PMID:6610

Abstract

Sodium influx was measured in isolated, previously perfused gill arches of rainbow trout, Salmo gairdneri, by measuring incorporation of 22Na into gill tissue following timed exposure to a 1 mM 22NaCl medium. Transport rates approximated those estimated for intact fish and were linear for at least one min. 2. NH4Cl-containing perfusates at pH 7 and 8 stimulated Na+ influx equally, indicating that only ionized ammonia is important in the transport process. A Na+/NH4+ exchange at basal and/or lateral membranes of the transporting cells is suggested. 3. Low-sodium Ringer perfusate augmented Na+ influx; in one group of gills the transport rate was more than double that of NaCl Ringer controls. The increase in transport induced by internal NH4+ was not additive with the low sodium augmentation. A reduction in intracellular (Na+) is postulated as the mechanism operating in both cases. 4. Ouabain had no appreciable effect on Na+ influx, either with or without NH4+ in the perfusate. Diamox partially blocked the augmented Na+ influx induced by NH4+. Amiloride completely inhibited Na+ influx, both with and without NH4+ in the perfusate.

摘要

通过在1 mM ²²NaCl培养基中定时暴露后测量²²Na掺入鳃组织的情况，在分离的、先前已灌注的虹鳟（Salmo gairdneri）鳃弓中测量钠内流。转运速率接近完整鱼的估计值，并且至少在一分钟内呈线性。2. pH值为7和8的含NH₄Cl灌注液对Na⁺内流的刺激作用相同，表明只有离子化氨在转运过程中起重要作用。提示在转运细胞的基底膜和/或侧膜存在Na⁺/NH₄⁺交换。3. 低钠林格氏灌注液增加了Na⁺内流；在一组鳃中，转运速率比NaCl林格氏对照高出一倍多。内部NH₄⁺诱导的转运增加与低钠增加无叠加作用。推测在这两种情况下起作用的机制是细胞内（Na⁺）的减少。4. 无论灌注液中有无NH₄⁺，哇巴因对Na⁺内流均无明显影响。二氮嗪部分阻断了NH₄⁺诱导的增加的Na⁺内流。氨氯吡咪完全抑制了灌注液中有无NH₄⁺时的Na⁺内流。