Normal Metabolism of Ammonia

Mean Ammonia Uptake by Muscle in Eck Fistula Docs in Metabolic 

Dog No. 3 was omitted because of insufficient data. It is apparent that a marked uptake of ammonia occurs in tissues in metabolic acidosis. In alkalosis the uptake by tissues is only slightly greater than normal, and the arterial levels of ammonia are comparable with normal values. The elevation of blood ammonia which occurs on vigorous acidification of the animal might not be due to a drop in permeability with pH, but might be due to a phenomenon reported by Krebs and Henseleit (K4). Urea synthesis by liver slices is directly proportional to the pH and C02 content of the medium. Table 2, constructed from data reported in this paper, shows this dependence. 

Dependence of Urea Synthesis by Liver Slices on pH and COa Content 

Thus the drop in ammonia content of plasma in alkalosis may be related to the pH effect on urea synthesis rather than to the alterations in permeability caused by changes in pNHs. The treatment of hepatic coma by acidification with C02 would lower pH, inhibiting synthesis of urea. This would cause a rise in blood ammonia. The same type of change could be brought about by infusion of HC1, which would have a double effect on urea synthesis by lowering both pH and bicarbonate. It does not appear necessary to invoke a penetration hypothesis to explain the 

The techniques for the determination of quantities of ammonia such as are found in body fluids, that is, of the order of one microgram per milliliter, have been developed only recently. All methods for the determination of ammonia in animal fluids are based on two general processes. The first is the conversion of the ammonium ion to gaseous NH3 and its segregation in a separate aliquot of solution. The second is the application of some technique for the quantitation of this isolated ammonia. 

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