Substance P Content and Effect on Capillary Permeability of Extract of Various Parts of Human Brain

Abstract

CHEMICALLY pure substance P, apart from causing vasodilatation and stimulation of smooth muscle¹, also increases capillary permeability². We have now tested extracts of four parts of human brain, containing different amounts of substance P, for their effectiveness in increasing capillary permeability. The effects on the guinea pig ileum of acid-boiled extracts of substantia nigra, basal ganglia, cortex and cerebellum were compared with the effect of a standard preparation of substance P made from bovine intestine (for methods, see ref. 3). The results are listed in Table 1, col. 3. For estimating the effects of the brain extracts on capillary permeability, other vasoactive substances (acetyl choline, adrenergic amines, histamine, serotonin, ATP, ADP and AMP) had to be removed so far as possible; this was done by successive precipitations with ammonium sulphate and acetic acid-ether. The resulting ‘purified extracts’ were tested for activity in increasing capillary permeability of rabbit skin, using a modification of the method of Frimmer and Müller⁴.