The action of inorganic salts on the secretion of the isolated kidney

Abstract

In a recent paper by Starling and Verney (1) an attempt was made to study the functions of the kidney by the synthetic method. The organ cut out of the body was perfused with blood at the normal temperature and at any desired pressure from a heart-lung preparation. Under these conditions it was found to retain a considerable proportion at any rate of its fundamental functions. It gave a copious secretion of hypotonic urine, the amount varying with the blood pressure and with the dilution of the blood. By means of this preparation it seemed possible to build up the complete activities of the organ as they are found in the living body, by alteration of the conditions of the experiment, and thus to form an idea of the different factors involved in its normal activities. Thus, the low chloride content of the urine obtained from the perfused kidney shows that some factor is absent in the conditions of the experiment which is present in the kidney in situ . Reabsorption of chloride is evidently at its maximum, and we can raise the chloride percentage, either by restoring the factors which are normally present in the intact animal, or by paralysing all the activities of the tubules which tend to modify the composition of the glomerular filtrate. The method also allows us to use two kidneys at the same time, fed from the same heart-lung preparation. These two kidneys may be identical, so that one serves as a control of the other, or they may be from different dogs, or in different conditions resulting from varying periods of interruption of the circulation through them, or from the natural occurrence or experimental induction of nephritis. The use of two kidneys allows us to distinguish between effects in the urine due to changes in the circulating fluid and those which are due to alterations in the kidney itself. If the changes in the one kidney are localized, as apparently occurs in some forms of nephritis, we may use this method for attacking the question of the localization of function in the kidney. The work of Hamburger (2) and his pupils on the perfusion of frogs’ kidneys has shown the part played by the relative properties of Ca, K and NaHCO 3 in the Ringer’s fluids used in the perfusion. Our knowledge of the influence of the normal saline constituents of the blood on the secretion of the kidney in situ or fed with blood is extremely scanty. We propose in this paper to deal with the effect produced on the functions of the kidney by alterations in the amounts of K, Ca and phosphate ions present in the blood circulating through the kidney.