1905-6.] Standardising Suprarenal Preparations. 
165 
Many commercial preparations of sodium nitrite are very 
impure and contain considerable quantities of the nitrate. The 
sodium nitrite of Merck is practically pure. The crystals were 
kept dry and the solutions were freshly made. When made in 
this way, the solution of nitrite is practically of uniform 
strength. 
Nitrites have been largely used in perfusion experiments. 
Atkinson * perfused frogs with solutions of sodium nitrite (con- 
taining 99 per cent, of nitrite by the permanganate method), 
and he got dilatation of the vessels in solutions of from 1 in 100 
to 1 in 100,000 — the increased flow in the latter case being from 
16-18 per cent. A solution of 1 in 200,000 was without effect. 
He also perfused nitroglycerin, and got an increased flow up to 
a dilution of 1 in 1,000,000. 
Leech f perfused decapitated tortoises with solutions of sodium 
nitrite and collected the fluid in graduated flasks. After a 
preliminary contraction, dilatation of the vessel wall resulted 
with strengths of from 1 in 1000 to 1 in 10,000. This preliminary 
contraction was not seen on perfusing the kidneys of warm- 
blooded animals. He also found marked dilatation on perfusion 
of the lungs of a cat killed by chloroform. Leech calls attention 
to a certain resemblance between the action of alcohol and that 
of the nitrites, but he states that the nitrites are more rapid and 
also more evanescent in their action. Marshall,! in the course 
of his experiments on the antagonism of digitalis and the nitrites, 
perfused sheep’s kidneys with sheep’s blood, and demonstrated 
that there was not chemical antagonism, but that each drug 
produced its own effect, which varied with the length of time 
and the rapidity of action, and also with the strength of the 
solution. 
Both the perfusion method in pithed frogs and blood pressure 
in rabbits were used as a means of estimating the effect of 
adrenalin and a nitrite given together. 
(i a ) Perfusion . — A solution of adrenalin of the strength of 
005 per cent, of 1 in 1000 gives a marked constriction when 
perfused in a pithed frog. Sodium nitrite (Merck) was added 
* Loc. cit. 
f Brit. Med. Journal , vol. i., 1893, p. 1305. + Loc. cit. 
