Bicarbonate concentration in rhesus monkey and guinea pig fetal lung liquid

Fetal lung liquid secretion is essential for the normal growth of the lung in utero. Previous studies of fetal lung liquid secretion, mostly performed in lambs, have demonstrated that it has high Cl and very low HCO3- concentrations relative to plasma values. Because it is unknown whether primates have a similar electrolyte profile in their lung liquid, we sampled the lung liquid from rhesus monkeys (Macaca mulatta) at 127 to 128 days gestation (0.8 gestation). Although we found that lung liquid Cl concentration was higher than plasma values (p < 0.05), the HCO3- concentration was the same as in the plasma. This indicates that nonhuman primates, relative to lambs, have different cellular mechanisms for regulating fetal lung liquid HCO3- concentrations.