Acidosis,Hypercalcemia,and Hyperphosphatemia in Rat Fetuses near Term and Effects of Maternal Acid/Base Loading 1

Abstract

Summary

In the rat fetus, under normal conditions, blood calcium, phosphorus, and pCO₂ rise, and pH declines, during the last 6 days of gestation. Little or no correlation is seen between changes noted in the maternal organism and those occurring in her unborn offspring.

Oral administration of NH₄Cl to pregnant females results in a lowering of maternal blood pH, with no change in blood calcium, phosphorus, or respiratory gases. NaHCO₃ administration does not alter any of these parameters. In contrast, profound changes are observed in the fetuses of both acid- and alkali-treated dams. With NH₄Cl feeding, fetal pH falls while blood calcium, phosphorus, and pCO₂ rise; with NaHCO₃ administration, fetal blood pH increases and serum calcium, phosphorus, and pCO₂ decline.

These observations point strongly to an association between fetal blood pH and circulating levels of calcium and phosphorus, and suggest that the levels of these elements may be, in part, determined by the acid/base status of the organism in utero.

The authors wish to express their appreciation to Dr. Carl H. Smith and Mrs. Donna Breidenbach for their help and for making available facilities at Children's Hospital where all pH and blood gas determinations were done.