In Part I the results were reported of experiments on the relation between absorption of water by the gut and its excretion by the kidney. Demonstration was also given to the independence of excretory response and innervation of the kidney. In the present paper, use being largely made of the method detailed in Part I, our object will be to describe the effects of some factors influencing this response, and finally to select the hypothesis which, on the one hand, may best embrace the facts of this and previous work of a relevant nature, and, on the other, serve as a fruitful source and guide for future investigation. II.
Results of Experiments
. (
a
)
The Effect of Exercise on the Responses of the Innervated and Denervated Kidneys to Water-ingestion
.—The inhibition, by exercise, of the response of the kidneys to water-ingestion has been commonly ascribed to a concomitant diminution in the supply of blood to the kidney, either as the passive result of redistribution of capacity in the vascular system, or as the result of an increased activity in the vaso-constrictor nerves. The possibility of its being due, through similar causes, to an inhibition of absorption by the gut must also be considered. MacKeith, Pembrey, Spurrel, Warner, and Westlake (1923), in a paper dealing with the adjustment of the human body to muscular work, report some observations on the effect of exercise on the diuretic response to 560 c. c. hot tea taken by mouth. They were led, by the results of their experiments, to suggest that the suspension of the activity of the kidneys during running arose from an early outflow of constrictor impulses to the renal vessels.
When a large volume of water is given by mouth to the normal dog, there is usually a delay of about 10 minutes before the kidney begins to respond, and of about 50 minutes before the response reaches its maximum intensity, fig. 1. It was with the main object of apportioning this delay between the processes involved in the transport of the water, and of determining the relationship between the water-load of the body and the rate of excretion of water by the kidneys, that the work described in this paper was undertaken. As will be seen later, we have used a method which, in allowing the secretion of one kidney to be collected separately from that of the other, has offered the means of answering cognate questions involving the influence of some factors of physiological significance on the response of the kidney to water-ingestion. To these questions consideration will be given in part II, where all the facts in their theoretical interrelationship will be discussed. The delay referred to above, might be allocated theoretically to one or more of several sites and functions. First, the water might be retained in the stomach, its passage into the small gut being accurately and rapidly reflected in its excretion by the kidney. Second, absorption itself might be the principal seat of delay. Third, there might be a latent period between absorption and excretion, the spatial representation of the events occurring in this time not being, of necessity, restricted to the kidneys.
Somatic ammonia, the daily production of which in the dog is estimated to be about 220 mg. NH3N, is absorbed by the lungs and heart, and probably converted finally into urea, the total production of which amounts to about 4000 mg. urea nitrogen per day.
In oxygen deficiency and in the later hours of an acute experiment the lungs and heart produce large amounts of ammonia, the rate of production being similar to that by the kidneys.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.