This article outlines the salient details of volume-sensitive K and Na fluxes in Amphiuma red blood cells. Based upon electrical measurements and force flow analyses, it has been determined that swelling-induced K loss is due to an obligatorily coupled (1:1) electroneural K/H exchanger. Similarly, the net Na flux observed in osmotically shrunken cells has been determined to be the result of an electroneutral Na/H exchange pathway. Studies employing the Ca2+ ionophore A23187 suggest a role for Ca2+ in activating K/H exchange yet an increase in the sensitivity of the K/H exchange apparatus of swollen cells suggests that swelling-induced activation of K/H exchange is not simply the consequence of increased intracellular free Ca2+. Finally, while the K/H exchanger is volume sensitive, it is also kinetically modulated by [H+]. As [H]0 is increased, net K/H exchange flux is increased at fixed driving force, suggesting that, in addition to a volume regulatory role, the K/H exchanger may also function to buffer plasma H.
|Original language||English (US)|
|Number of pages||16|
|State||Published - 1985|
ASJC Scopus subject areas
- Biochemistry, Genetics and Molecular Biology(all)