CHANGES IN VASOACTIVE PROPERTIES OF BLOOD PRODUCTS WITH TIME AND ATTEMPTED IDENTIFICATION OF THE SPASMOGENS

The contractile activity of various fresh, or incubated blood fractions was studied in vitro using the isolated canine basilar artery. Significantly greater contraction was induced by fresh platelet rich plasma (PRP) and serum compared to red blood cells (RBC). Following incubation, the contractile activity of RBC increased, reaching a plateau at day-3 and it was maintained for at least 14 days, while both PRP and serum lost most of their activity after 24 h of incubation. The contractions induced by fresh blood fractions were only partially blocked by desensitization of 5-hydroxytryptamine (5-HT) receptors or by the 5-HT antagonist methysergide. D-600 [methoxyverapamil] effectively antagonized the response to all blood fractions. Biochemical analysis of the incubated RBC by means of Sephacryl S-200 column chromatography and SDS[sodium dodecylsulfate]-urea polyacrylamide gel electrophoresis revealed that the contractile substance possessed a MW of .apprx. 60,000 dltons. Vasoactivity was only present in 1 peak of the chromatographically eluted fractions which was shown to possess a similar absorption spectrum to that of Hb. Hb concentration was highest in day 3, 7 and 14 fractions and may be correlated with the contractile activity of incubated samples.