Effect of changes in respiratory blood parameters on equine red blood cell K-Cl cotransporter.
K influx into equine red blood cells (RBCs) was measured using 86Rb as a tracer for K under conditions designed to mimic the changes in respiratory blood parameters that occur in vivo during strenuous exercise. The effects on K influx of physiological changes in pH, cell volume, O2 tension (PO2), CO2 tension (PCO2), and bicarbonate and lactate concentrations were defined. Physiological PO2 exerted a dominant controlling influence on the H(+)-stimulated Cl-dependent K influx, consistent with effects on the K-Cl cotransporter, PO2 required for half-maximal activity was 37 +/- 3 mmHg (4.9 kPa). Although RBCs were swollen at low pH, results showed explicitly that the volume change per se had little effect on K influx. Lactate had no effect on volume- or H(+)-stimulated K influxes, nor did bicarbonate or PCO2 affect the magnitude of K influxes after these stimuli or after treatment with protein kinase/phosphatase inhibitors. These results represent the first detailed report of O2 dependence of H(+)-stimulated K-Cl cotransport in RBCs from any mammalian species. They emphasize the importance of PO2 in control of RBC K-Cl cotransport.
Speake
P F
PF
Department of Veterinary Preclinical Sciences, University of Liverpool, United Kingdom.
Roberts
C A
CA
Gibson
J S
JS
D000818:Animals; D001639:Bicarbonates / Q000097:blood; D001834:Body Water; D002245:Carbon Dioxide / Q000097:blood; D002352:Carrier Proteins / Q000097:blood*; D004912:Erythrocytes / Q000378:metabolism*; D006400:Hematocrit; D006736:Horses / Q000502:physiology*; D006863:Hydrogen-Ion Concentration; D007773:Lactates / Q000097:blood; D010100:Oxygen / Q000097:blood*; D010313:Partial Pressure; D005082:Physical Exertion / Q000502:physiology*; D011188:Potassium / Q000097:blood*; D012119:Respiration; D012414:Rubidium Radioisotopes / Q000097:blood; D027981:Symporters; D000096922:K Cl- Cotransporters
D001639:Bicarbonates; D002245:Carbon Dioxide; D002352:Carrier Proteins; D007773:Lactates; D010100:Oxygen; D011188:Potassium; D012414:Rubidium Radioisotopes; D027981:Symporters; D000096922:K Cl- Cotransporters