166 Proceedings of Poyal Society of Edinburgh. [sess. 
to the solution. Until 6 per cent, of the nitrite was added, the 
adrenalin constriction was still given. When this strength was 
reached, no constriction appeared even with continued perfusion, 
but a slight dilatation was present. When the perfusion of the 
mixture was stopped and Locke’s solution was used, the nitrite 
effect rapidly passed off, and a prolonged adrenalin effect was 
given. The nitrite apparently could only antagonise the effect 
of the adrenalin or delay its action while the two drugs were 
being perfused through the vessels. 
A typical experiment in which antagonism was not established 
may be given, as it demonstrates the influence of both drugs on 
the vessels. 
After perfusion for 35 minutes. 
Solution. 
Time. 
Drops per minute. 
1-25 
20 
Locke’s. 
1-27 
20 
1'28 
Sod. nitrite, 0'5 per cent. 
1-38 
46 
1-41 
44 
1*43 
48 
1*48 
44 
1*50 
Locke’s. 
1-56 
40 
2*0 
40 
2‘4 
28 
2‘8 
22 
2*25 
Sod. nitrite, 0’25 per cent. ; 
2*28 
adrenalin, 0 *05 per cent. 
2*35 
6 
2*38 
10 
(b) Blood Pressure. — The effect of nitrites on the blood 
pressure has been extensively studied. 
Lauder Brunton * investigated the fall of blood pressure caused 
by the inhalation of amyl nitrite. Atkinson,! in experiments 
on rabbits with their vagi intact, got a fall of blood pressure and 
acceleration of the pulse with a dose of J grain of sodium nitrite. 
A similar result was obtained with much smaller doses of nitro- 
glycerin. The pressure fell with 1 in 1500, hut with 1 in 50,000 
* Journal of Anatomy and Physiology, vol. v. p. 92. 
t Log. cit. 
