A pharmacologically active substance in mammalian tissue extracts

Publisher Website
Google Scholar
Abstract
Isolated goldfish intestine may be used to detect and measure very small amounts of the pharmacologically active polypeptide known as substance P in a purified extract of mammalian brain or intestine. However, when this test was applied to crude extracts of guinea-pig tissues, the estimate was more than 1000 times too high. The substance responsible for this effect was purified by gel filtration and anion exchange chromatography. Spectral data on the purified material, before and after hydrolysis, coupled with the appearance of a pentose sugar and uracil as products of hydrolysis, suggested that a uridine nucleotide was present. Uridine diphosphate and uridine triphosphate were both active in this test. Purified extracts were compared with authentic samples of these two nucleotides by bioassay and by optical density measurements. The active substance in liver extract was identified as uridine diphosphate since the 2 results agreed quantitatively when this substance was used as a standard. The effective dose is about 1 ng, which is the amount present in less than 5 [mu]g of guinea-pig liver. Goldfish intestine may thus be used to estimate small amounts of either substance P or uridine diphosphate, but, if both are present, steps must be taken to separate them.