OBSERVATIONS ON THE EFFECTS OF RENAL ISCHÆMIA UPON ARTERIAL PRESSURE AND URINE FLOW IN THE DOG
Authors: Verney E. B. , Vogt Marthe 
Published: December 2014

1. Methods for producing temporary obstruction, complete or partial, of the renal artery in the dog are described.

2. Occlusion of the artery to a sole remaining kidney for periods ranging between 2 sec. and 600 sec. produces, subject to the reservation in paragraph 3 below, contemporary suppression of urine flow without accompanying or subsequent change in arterial pressure as measured by the method of the carotid loop with denervated sinus.

3. In some animals long lasting suppression of urine, and hypertension, have been observed to follow short periods (from 5 to 120 sec.) of arterial occlusion (figs. 4 and 5). These responses resemble those accompanying prolonged but partial obstruction of the renal artery (see paragraph 4 below). The conditions of their occurrence are not known.

4. When the artery to a sole remaining kidney is partially obstructed, the arterial pressure is rising some 8 to 18 minutes later towards a plateau from which it slowly falls when the obstruction is released. The results suggest that the period of recovery in blood pressure is a function of the period of arterial obstruction (Table I). They occur whether or no the splanchnic and the renal nerves have been divided. No rise in pressure has been observed unless the urine flow, during water‐diuresis, has been at least strongly inhibited by the arterial obstruction.

5. When the renal artery on one side is partially obstructed, the contralateral kidney being present, either no rise in arterial pressure ensues, or a rise from which recovery occurs apparently more quickly than in comparable experiments in which the contralateral kidney is absent.

6. The view that the increase in arterial pressure referred to in paragraph 4 above is of humoral origin, is confirmed by the occurrence of a similar phenomenon in preparations in which a kidney has been transplanted to the neck of a decerebrated and nephrectomised dog. Either release of the obstruction, or removal of the kidney, is followed by a gradual return of the arterial pressure to its original value. In order to produce increases in general arterial pressure in such preparations, the reduction in renal arterial pressure needs to be severe: the resultant increases in general arterial pressure are, notwithstanding, much smaller than in survival experiments.

7. The results suggest that the cause of the rapid blood‐pressure response to compression of the renal artery by means of a previously implanted unit, is the same as that of the persistent hypertension which follows permanent obstruction of the renal artery by operative procedures.

8. Functional removal of a chronically ischæmic and sole remaining kidney was followed by a gradual fall in arterial pressure. The hypertension had disappeared within 4 hours, and thereafter the pressure remained constant for 16 hours.

9. Animals in which an anastomosis has so been made between the renal segment of the I. V. C. and the portal vein that all the renal venous blood is conducted directly to the liver, respond to the induction of renal ischæmia in ways similar to those in which normal animals respond. It is improbable, therefore, that the liver plays an elective rôle in the inactivation of either the pressor agent or, if we assume these substances not to be identical, the agent responsible for convulsive “uræmia.”

10. Consideration of the results reported in this paper shows them to be compatible with the view that normal renal tissue both depresses the rate of formation of the pressor agent by ischæmic renal tissue, and accelerates, by a process of excretion or inactivation, the rate of its disappearance from the blood; further, that when the period of renal ischæmia is long (e.g. 3 hours) the production of the pressor agent continues for some hours after the mechanical release of the obstruction to the renal artery.

Grateful acknowledgment is made to the Government Grant Committee of the Royal Society for defraying part of the expenses incurred in this work.