Association between cholesterol and 2,3-diphospho¬ glycerate in genetically selected hooded rat lines

We have developed two strains of hooded rats with differing erythrocyte oxygen affinities by selection on red cell 2,3-diphosphoglycerate levels. Genetic studies have shown that these strains differ at one DPG-level-determining locus. This article reports the results of a study whieh involved measurement of plasma cholesterol levels in rats from the strains and the Fe progeny of strain inter-crosses. Low-DPG strain rats, with high oxygen affinity, had significantly higher mean cholesterol levels than High-DPG rats. Animals from the extremes of the F2 distribution of DPG levels showed similar, significantly different mean cholesterol levels, indicating that the negative association between DPG and cholesterol levels in strain rats was not due to inadvertent fixation of unrelated genes during selection on DPG. The possibility is discussed that high oxygen affinity, brought about by low DPG levels, may be causative in increasing cholesterol levels. KEY WORDS: cholesterol; 2,3-diphosphoglycerate; oxygen affinity; hooded rats