Glutaminase Activity of the Fœtal Membranes and Kidneys of Pigs

Abstract

AT a Ciba Foundation Colloquium on the effects of ageing on electrolyte metabolism, Widdowson and McCance¹ reported the pH of allantoic fluid to be between 5.5 and 6 at 46 and 67 days of gestation. Ammonia accounted for about 25 per cent of the “titratable acidity + ammonia” of these fluids. The total osmolar concentration of the allantoic fluid had been shown before to be only one-third to one-half that of fœtal serum at the same times of gestation, mainly due to the low concentration of sodium in the fluid². When, therefore, Widdowson and McCance found that the acidity of allantoic fluid was largely due to high concentrations of carbonic acid, they suggested that active sodium re-absorption by hydrogen-ion exchange might be occurring in the fœtal membranes and kidneys. In support of this, they reported considerable carbonic anhydrase activity in the fœtal kidneys and membranes lining the allantoic sac.