Lactate transport in canine red blood cells.
OBJECTIVE
To detect monocarboxylate transporters (MCTs) in canine RBC membranes and to determine the distribution of lactate between plasma and RBCs.


METHODS
Blood samples obtained from 6 purpose-bred Beagles.


METHODS
Monocarboxylate transporter isoforms 1, 2, 4, 6, 7, and 8 and CD147 were evaluated in canine RBCs by use of western blot analysis. Lactate influx into RBCs was measured as incorporation of radioactive lactate.


RESULTS
2 MCT isoforms, MCT1 and MCT7, were detected in canine RBC membranes on western blot analysis, whereas anti-MCT2, anti-MCT4, anti-MCT6, and anti-MCT8 antibodies resulted in no signal. No correlation was found between the amount of MCT1 or MCT7 and lactate transport activity, but the ancillary protein CD147 that is needed for the activity of MCT1 had a positive linear correlation with the rate of lactate influx. The apparent Michael is constant for the lactate influx in canine RBCs was 8.8 +/- 0.9mM. Results of in vitro incubation studies revealed that at lactate concentrations of 5 to 15mM, equilibrium of lactate was rapidly obtained between plasma and RBCs.


CONCLUSIONS
These results indicated that at least half of the lactate transport in canine RBCs occurs via MCT1, whereas MCT7 may be responsible for the rest, although an additional transporter was not ruled out. For practical purposes, the rapid equilibration of lactate between plasma and RBCs indicated that blood lactate concentrations may be estimated from plasma lactate concentrations.
Koho
Ninna M
NM
Department of Basic Veterinary Sciences, University of Helsinki, POB 66, FIN-00014 Helsinki, Finland.
Raekallio
Marja
M
Kuusela
Erja
E
Vuolle
Jaana
J
Pösö
A Reeta
AR
D000818:Animals; D001692:Biological Transport; D004285:Dogs; D004912:Erythrocytes / Q000378:metabolism*; D007700:Kinetics; D007773:Lactates / Q000097:blood* / Q000493:pharmacokinetics; D027501:Monocarboxylic Acid Transporters / Q000097:blood / Q000378:metabolism
D007773:Lactates; D027501:Monocarboxylic Acid Transporters