AJP - Regulatory, Integrative and Comparative Physiology, Vol 264, Issue 3 481-R486, Copyright © 1993 by American Physiological Society
Biochemical bases for difference in oxygen affinity of maternal and fetal red blood cells of rattlesnakes
F. R. Ragsdale and R. L. Ingermann
Department of Biological Sciences, University of Idaho, Moscow 83843.
Pregnancy in Crotalus viridis oreganus is associated with an increase in
the nucleoside triphosphate (NTP) concentration and a concomitant decrease
in the oxygen affinity of the adult red blood cell. However, although the
red blood cells of non-pregnant adults and fetuses have indistinguishable
NTP concentrations, they have different oxygen affinities. Therefore, red
blood cell NTP concentrations alone cannot account for the oxygen-affinity
difference between fetal and maternal red blood cells. Hemoglobins from
adult and fetal snakes had similar intrinsic oxygen affinities; however,
adult hemoglobin was more responsive to organic phosphate modulation
compared with fetal hemoglobin. Structural differences, indicated by native
gel electrophoresis and electrophoresis of the globins under denaturing
conditions at high pH, corroborated functional differences of hemoglobins
from fetus and adult. Therefore, the biochemical basis for the
oxygen-affinity difference between maternal and fetal red blood cells in
this rattlesnake appears to be unique. It appears to be caused by a
functionally distinct fetal hemoglobin and the pregnancy-associated rise in
red blood cell NTP levels in the mother.
