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The work of Gomes on the polypeptide in human urine which causes contraction of the rat uterus has been extended. Concentrates were prepared by means of paper pulp columns similar to those used by Rocha e Silva and his colleagues for the purification of bradykinin, and evidence was obtained for the presence of two different active substances not only in human urine but also in a preparation of bradykinin. The effect of human urine on the rat uterus is probably due to bradykinin itself or a mixture of similar substances.

A kininogenase (CGK) in the coagulating gland of the guinea-pig was partially purified, characterized and separated from a kininase also present in the gland. This kininogenase is not inhibited by the usual kininogenase and protease inhibitors. Our results indicate that it is identical with the esterolytic enzyme in the gland which hydrolyses the synthetic ester TAME. The kinin released by CGK from dog's crude pseudoglobulin was purified more than 1500 times and identified as bradykinin by chromatography on paper, on carboxymethyl-cellulose columns, and on silica gel.

Previous work has shown that endogenous chemical mediators, of which histamine is the prototype, increase the permeability of blood vessels by causing gaps to appear between endothelial cells. In the present paper, morphologic and statistical evidence is presented, to suggest that endothelial cells contract under the influence of mediators, and that this contraction causes the formation of intercellular gaps. Histamine, serotonin, and bradykinin were injected subcutaneously into the scrotum of the rat, and the vessels of the underlying cremaster muscle were examined by electron microscopy. To eliminate the vascular collapse induced by routine fixation, in one series of animals (including controls) the root of the cremaster was constricted for 2-4 min prior to sacrifice, and the tissues were fixed under conditions of mild venous congestion. Electron micrographs were taken of 599 nuclei from the endothelium of small blood vessels representing the various experimental situations. Nuclear deformations were classified into four types of increasing tightness (notches, foldsl closing folds, and pinches. In the latter the apposed surfaces of the nuclear membrane are in contact). It was found that: (1) venous congestion tends to straighten the nuclei in al groups; (2) mediators cause a highly significant increase in the number of pinches (P < 0.001), also if the vessels are distended by venous congestion; (3) fixation without venous congestion causes vascular collapse. The degree of endothelial recoil, as measured by nuclear pinches, is very different from that caused by mediators (P < 0.001). (4) Pinched nuclei are more frequent in leaking vessels, and in cells adjacent to gaps (P < 0.001); (5) mediators also induce, in the endothelium, cytoplasmic changes suggestive of contraction, and similar to those of contracted smooth muscle; (6) there is no evidence of pericyte contraction under the conditions tested. Occasional pericytes appeared to receive fine nerve endings. Various hypotheses to explain nuclear pinching are discussed; the only satisfactory explanation is that which requires endothelial contraction.

The biological activity of synthetic polypeptides containing the amino acids of natural pure trypsin-bradykinin and snake-venom-bradykinin has been investigated. A series of tests for bradykinin-like activity in stimulating plain muscle, depressing the blood pressure and increasing capillary permeability was used on various species. A nonapeptide with the following structure: H-L-Arg-L-Pro-L-Pro-Gly-L-Phe-L-Ser-L-Pro-L-Phe-L-Arg-OH elicited qualitatively and quantitatively the effects of the pure natural bradykinins. An octapeptide with the following structure: H-L-Arg-L-Pro-Gly-L-Phe-L-Ser-L-Pro-L-Phe-L-Arg-OH also exerted bradykinin-like effects but was 50 to 100 times less active than the nonapeptide. Three other octapeptides and a heptapeptide were without any significant effect. Further work will demonstrate if the nonapeptide A is synthetic bradykinin or a peptide with bradykinin-like activity.NOTE ADDED SINCE SUBMISSION OF THIS PAPER: The data from this investigation were personally precommunicated to Elliott, Lewis, and Horton, who have since found that the structure of pure trypsin-bradykinin is identical with the structure of the nonapeptide A. Therefore, this synthetic nonapeptide is in fact synthetic bradykinin.

Human urinary kinin (substance Z) has been extracted by modifications of the methods previously described by Gomes (1955) and Jensen (1958). The separation of two oxytocic fractions from such extracts by paper pulp chromatography (Walaszek, 1957; Jensen, 1958) could not be confirmed. Substance Z could not be distinguished from kallidin, bradykinin or glass-activated kinin by parallel quantitative assays, thus confirming that these four substances are very closely related.

The article discusses a study on decompression sickness and the bradykinin that tends to contract the muscles of the body. The research team was led by C. Chryssanthou of the Beth Israel Medical Center, New York City under the contract Office Naval Research. Chryssanthou mentions that a certain substance which he termed as Smooth Muscle Activating Factor or SMAF combines with smooth muscles to respond with bradykinin or histamine. A study of 2-4 phenylpiperazinylmethyl cyclohexanone or PPCH,an anti-gradykinin, anti-histaminic drug, is also presented in the article.