Depressor and Pressor Activity of Extracts from the Aortic Wall of Cattle.

Summary The depressor and pressor activity of extracts from the aortic walls of cattle have been investigated, using the extraction method described by Euler. The depressor action seems to a great extent to be due to the presence of histamine in the extracts. The pressor action of the extracts is due to some substance which in most cases mimics the action of nor‐adrenaline but in some cases is more like adrenaline. This difference in the action of the extracts is not due to the presence of different pressor substances but to the presence of contaminating histamine. Traces of histamine, though masked in its action on the blood pressure by the pressor substance, may cause a liberation of adrenaline in the test‐animal itself. The expenses of this investigation were defrayed by a grant from the Therese and John Andersson Memorial Foundation.