The Effect of Liver Extract on Ducks.

Abstract

In previous communications 1 it was pointed out that liver extract contained both histamine and cholin, and that the depressor effect was possibly due to these substances. As a further link in the evidence leading to these conclusions the effect of liver extract has been tried on ducks. Hogben 2 has stated that a 1 per cent extract of liver is without effect on ducks, that ducks are less susceptible to depressor bases, and that a pressor effect is more likely, as in rabbits.

The ducks used were fairly uniform in size, weighing about 2 kilos each. Intravenous injections of liver extract (kindly furnished by the Connaught Laboratory) were made in doses ranging from 0.25 to 1 cc. The blood pressure was taken from the carotid artery by the usual method. Such injections are practically without effect on the blood pressure. Sometimes there is a slight rise, sometimes a slight fall (usually due to manipulations), but never the abrupt fall so characteristic of the depressor effect in mammals. As liver extract contains histamine and cholin, the conclusion is still further justified that it is these substances that are responsible for its depressor effect.

Incidentally, it may be stated that Miss Ruth Holzapfel finds radiation with ultraviolet light has no injurious effect on the depressor substance of liver. We know from Ellis and Newton 3 that ultraviolet rays destroy the potency of insulin. It was thought the same might be true for liver extract, if the depressor substance was in the nature of an autocoid. This is a tentative statement as her experiments are yet too few to be conclusive.