Nature of the depressor agent in extracts of rabbit kidneys

Abstract

The nature of the depressor substance in extracts of rabbit kidneys was investigated. In addition to lowering blood pressure the extracts were found to inhibit motility of isolated rabbit intestine, stimulate isolated uterus, cause blanching of rabbit and rat kidney, cause slowing of the heart and prolongation of the P-R interval. These same effects are produced by adenosine and its nucleotides. The depressor substance was shown not to be acetylcholine, choline, histamine or kallikrein. Analysis of the kidney tissue extract by means of column chromatography and measurement of ultraviolet absorption revealed the presence of approximately equal amounts of adenosine mono-, di- and triphosphate as well as lesser amounts of other nucleotides. The amounts of the adenosine derivatives present are sufficient to account for the degree of blood pressure lowering produced by the unfractionated kidney extract. On the basis of this quantitative agreement and the pharmacological effects noted it is concluded that the depressor action of rabbit kidney extract is due to its content of adenosine nucleotides.