Regulation of ion transport across lamprey (Lampetra fluviatilis) erythrocyte membrane by oxygen tension.
We have measured the effects of oxygen tension on the transport of Na+, K+ and Cl- across the erythrocyte membrane of the lamprey Lampetra fluviatilis. The transport of each ion was affected by the oxygen tension of the medium. Hypoxic conditions (PO2 2 kPa) caused an increase in the acidification-induced influx of Na+ via Na+/H+ exchange. The influx of K+ was only slightly affected by the oxygenation of the medium. In contrast, the basal K+ efflux, measured using the radioactive isotope 43K, was markedly reduced by decreasing the oxygen tension of the medium, whereas the K+ flux in hypotonic medium was not affected. Only minor effects of hypoxic conditions on the influx of Cl- were observed in either isotonic or hypotonic conditions (there was a tendency for the isotonic influx to increase) or on the efflux in isotonic conditions. However, deoxygenation caused a marked reduction in the Cl- efflux in hypotonic conditions. The results show that oxygen tension has a marked effect on the pH and volume regulatory transport pathways of lamprey erythrocytes. For K+ and Cl-, the regulation appears to be asymmetric, i.e. influx and efflux are affected differently.
Virkki
L V
LV
Department of Biosciences, University of Helsinki, Finland. leila.virkki@quickmail.yale.edu
Salama
A
A
Nikinmaa
M
M
D000818:Animals; D002712:Chlorides / Q000097:blood; D004910:Erythrocyte Membrane / Q000378:metabolism*; D006863:Hydrogen-Ion Concentration; D000860:Hypoxia / Q000097:blood; D066298:In Vitro Techniques; D007424:Intracellular Fluid / Q000378:metabolism; D017136:Ion Transport; D007798:Lampreys / Q000097:blood*; D009997:Osmotic Pressure; D010100:Oxygen / Q000097:blood*; D011188:Potassium / Q000097:blood; D012964:Sodium / Q000097:blood
D002712:Chlorides; D012964:Sodium; D011188:Potassium; D010100:Oxygen