The Influence of Ammonium Salts on Cell Reaction

The recognition of the importance of the true reaction or hydrogen ion concentration of the blood and body fluids of organisms, as opposed to their titratable acidity, has been responsible in recent years for many important advances in physiology and for a large and rapidly growing body of literature. So great has been the interest in the determination, made possible by the development of the indicator and the electrometric methods, of the pH, as such, in the case of body fluids, sea water, culture media, etc., that the fact has rather generally been overlooked that the pH of the medium to which a cell is exposed bears no necessary relation to the pH produced by that medium within the cell itself. This is particularly true in the case of the most important of all of the various buffer systems found in organisms; namely, the carbonic acid-bicarbonate system. The author 1.~ has shown that the pH produced within a cell by a medium containing both C02 and bicarbonate can by no means be predicted from the pH of the medium as measured with indicators or electrometrically. Thus, cells composing the flowers of Symphytum peregrinum, which contain a natural indicator sensitive to weak acids, when exposed to the slightly alkaline solution resulting from the saturation of ~/2 NaHCO8 with COs, give visible evidence of a rise in intracellular acidity which is almost as rapid and striking as in the case of a strongly acid saturated solution of COs in distilled water, and far more rapid than in the case of solutions of HC1 whose hydrogen ion concentration is still greater.