Oxygen transport properties in malaria-infected rodents--a comparison
between infected and noninfected erythrocytes
W Schmidt, R Correa, D Boning, JH Ehrich and C Kruger
Department of Physiology, Medical School Hannover, Germany.
This study was performed to investigate oxygen transport properties in
whole blood (WB) of malaria-infected rats as well as in infected
erythrocytes (IE) and noninfected erythrocytes (NIE) separated by density
centrifugation. One week after inoculation with Plasmodium berghei, mean
parasitemia was 26.5% and high correlations were found between parasitemia
and hemoglobin concentration ([Hb]; r = -.902), mean cellular Hb
concentration (MCHC; r = -.712), MetHb (r = .923), and base excess (r =
-.922). Compared with control animals (C), the oxygen affinity was lower in
WB under standard (pH 7.40) and simulated "in vivo" (pH 7.00) conditions
(difference in P50, 5.7 and 5.1 mm Hg, respectively; 2P < .01, 2P <
.05). In IE Hb and 2,3-biphosphoglycerate (2,3-BPG) concentrations were
decreased (MCHC: IE 14.6 +/- 1.0, NIE 33.1 +/- 1.7 g/100 mL; [2,3-BPG]: IE
2.0 +/- 0.6, NIE 7.6 +/- 1.8 mmol/L), whereas [MetHb] and [ATP] were
increased ([MetHb]: IE 19.0 +/- 3.7, NIE 0.7% +/- 0.8%; [ATP]: IE 33.5 +/-
2.4, NIE 6.2 +/- 1.0 mumol/g Hb). At pH 7.40, half-saturation oxygen
tension (P50) was reduced in IE (29.6 +/- 2.6, NIE 39.2 +/- 5.4 mm Hg, 2P
< .001), which correlates with lower [2,3-BPG], increased MetHb content,
and higher intrinsic Hb- O2 affinity. However, at pH 7.00, the oxygen
affinity was lower in IE when compared with NIE, which was most likely due
to high [ATP] in IE. The resulting Bohr coefficients (BC) calculated for
CO2 and lactic acid were extremely high in IE and low in NIE (at 50%
O2-saturation BCCO2: IE -1.04 +/- 0.06, NIE -0.26 +/- 0.10, 2P < .001;
BCLac: IE -0.82 +/- 0.16, NIE -0.47 +/- 0.07, 2P < .001), which was
caused by different [2,3-BPG] and [ATP] as well as probably by structural
changes of the Hb molecule. The O2 capacity was 14.1 mL per 100 mL
erythrocytes in IE compared with 44.4 mL/100 mL in NIE. On the basis of the
calculated arterio-venous O2 difference under "in vivo" conditions, the
infected red blood cell fraction transports 30% of the O2 amount delivered
to the tissues by the noninfected cells (IE 8.0, NIE 26.9 mL/100 mL red
blood cells). We conclude that the O2 transport in malaria infected blood
is not only affected by the degree of anemia but also by the percentage of
infected erythrocytes.
Volume 83,
Issue 12,
pp. 3746-3752,
06/15/1994
Copyright © 1994 by The American Society of Hematology
