Rabbit aorta contracting substance

It is of interest how the presently accepted concept of aspirin and aspirinlike compounds involvement with PGs came about. The last of the aspirin theories to arise proposed that aspirin interfered with leukocyte migration to the site of injury, thus inhibiting the inflammatory process. A prostaglandin phase of inflammation, where PGs arose in the exudate of experimentally induced edema after the appearance of histamine and bradykinin, was already known. These two events appeared to coincide in the inflammatory process. Thus, the time was ripe. In studying the mediators responsible for the anaphylactic response in sensitized guinea pig lungs, Piper and Vane (1969) isolated histamine, SRS-A, and a new substance they called rabbit aorta contracting substance (RCS), a very unstable material (1 to 2 min) whose release, and presumably production, was selectively inhibited by aspirin-... 

Nykarnp FP, Flower RJ, Moncada S, Vane JR Partial purification of rabbit aorta contracting substance-releasing factor and inhibition of its activity by anti-inflammatory steroids. Ncutu/iz 263 479, 1976. 

Palmer MA, Piper PJ, Vane JR (1970) The release of rabbit aorta contracting substance (RCS) from chopped lung and its antagonism by anti-inflammatory drugs. Br J Pharmacol 40 581P-582P... 

Palmer, M. A., Piper, P. J., Vane, J. R., 1973 Release of rabbit aorta contracting substance (RCS) and prostaglandins induced by chemical or mechanical stimulation of guinea pig lungs. Br. J. Pharmacol. 49, 226-242. 

Administration of papaverine along with trichloroisobutyl alcohol and acetylbromodiethylacetylurea increases the effect of the latter two substances (333). In mice, small doses of papaverine reduce the convulsive effect of procaine not however the lethal dose (334). Papaverine inhibits contractions of excised muscles induced by adenosine derivatives (335). j8-Phenylisopropylamine in relatively high concentration increases the tonus of the vascular musculature of the surviving isolated rabbit aorta. This effect was inhibited by papaverine (336). The effect of papaverine on respiration, blood pressure in dogs and cats, on isolated vessels, on the intestine in situ and in vitro as well as its toxicity in rats was not affected by Nalorphine (337). Premedication... 

One draw-back of bioassay however is its inherent non-specificity. Reactions to bioactive substances not related to this field of biochemistry can generally be blocked by pretreatment of the assay organ with specific antagonists and inhibitors [212]. However, even using these precautions, many bioassay systems for detection and assay of TXAj are not entirely specific for this compound but react in a similar fashion also to the endoperoxides. This is the case with two of the most frequently used systems platelets and the rabbit aorta. Since endoperoxides may be present in parallel with TXA 2 in many biological situations, this non-specificity may create a problem. One possible solution is to use an assay more specific for TXAj the rabbit mesenteric artery, for example, has been reported to be contracted only by TXA 2 [215]. 

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