Levallorphan antagonizes the antidiuretic effect of morphine. It is at least 25 times as potent as nalorphine in this respect. However, neither levallorphan nor adiphenine antagonized the antidiuretic action of nicotine.Morphine and nicotine are both known to inhibit the diuretic response to water, an action mediated through the hypothalamic neurohypophysial system (De Bodo, 1944;Burn, Truelove, and Burn, 1945;Bisset and Walker, 1957). Nalorphine has been shown to antagonize the antidiuretic effect of one of these compoundsnamely, morphine (Winter, Gaffney, and Flataker, 1954;Schnieden and Blackmore, 1955) and levallorphan is known to be a very potent antagonist of certain of the actions of morphine (Fromherz and Pellmont, 1952). It therefore seemed of interest to see if this latter compound antagonized the antidiuretic effects of both morphine and nicotine. In addition, adiphenine hydrochloride (" Trasentin ") has also been reported to have certain antinicotinic actions (Tripod, 1949), and this compound was therefore also tested to see if it would antagonize the antidiuretic effects of nicotine. Ravent6s, and Walpole, 1946). To avoid injury to the animal's tail exposure was limited to 15 sec.; failure of the animals to react in this time was considered to indicate " complete analgesia."
METHODS
RESULTSLevallorphan and nalorphine are capable of antagonizing the inhibition of the renal response to a water load produced by morphine as illustrated in Table I. This Table also Neither adiphenine nor levallorphan antagonized the antidiuretic effect of nicotine, and adiphenine had no significant effect on the renal response to a water load (Table II); when comparing the effect of 0.9% sodium chloride solution with adiphenine, t = 1.9 P<0.1>0.05. However, adiphenine in a dose of 21 mg./kg. enhanced the antidiuretic effect of nicotine; when comparing nicotine with nicotine plus adiphenine, t = 2.4 P<0.05>0.01.