O'Connor & Verney (1945) and Verney (1947) showed that in dogs the inhibition of water diuresis resulting from an emotional stimulus was of two types, a rapid inhibition which could be abolished by section of the splanchnic nerves and denervation of the kidneys and suprarenals, and a slow inhibition due to the release of the antidiuretic hormone from the posterior lobe of the pituitary. The slow inhibition could be prevented by the injection intravenously of adrenaline i min. before the application of the emotional stimulus. These and other observations led them to the conclusion that adrenaline in some way prevented the release of the antidiuretic hormone, but not its action on the kidneys, i.e. that it acted centrally.Some observations made by Pickford (1939Pickford ( , 1947, and Duke, Pickford & Watt (1950) have shown that intravenously administered acetylcholine (ACh) in unanaesthetized atropinized dogs leads to the liberation of antidiuretic hormone, probably by an action on the supraoptic nuclei. It seemed worth testing whether adrenaline could prevent the ACh-induced release of the antidiuretic hormone, and the following observations were made with this object in view.
METHODSTrained dogs, after hydration and during water diuresis, were given intravenous injections of adrenaline chloride and ACh HCI dissolved in 1 ml. 0 9 % NaCl solution. The doses of adrenaline varied from 5 to 30 pg. and those of ACh from 0 5 to 3 mg. The drugs were injected either mixed in the syringe immediately before use, or the adrenaline was given 5-35 sec. before the ACh. In the latter case the needle was left in the malleolar vein and the syringe changed. The volumes of urine excreted over short intervals oftime both before and after the injections were noted. Ifthe duration of the diuresis allowed, the response to the mixed drugs was tested between two responses to ACh alone, or the injection of ACh was placed between two injections of the mixed drugs. Sometimes there was time for only two injections in the course of a water diuresis. Occasionally a second dose of water was given so that further responses could be observed at least on the same day. On three occasions measurements were made of the clearances of creatinine and diodone on urine samples collected over short intervals of time.Of the thirteen dogs on which observations were made, six had had their kidneys denervated by stripping the renal pedicle and dividing the capsule from all abdominal connexions.