Bioassay of prostaglandins in the presence of high concentrations of catecholamines.

A column filled with activated aluminium oxide is incorporated into the bioassay system of Vane in which a rat stomach strip, a chick rectum and a rat colon are superfused in cascade. The absorbance of catecholamines by the column and the passage of prostaglandins through the column are almost 100%. This modification of Vane's technique enables PGE1, PGE2, PGF2, F2a to be estimated at concentrations as low as 0-5--1-0 ng/ml in the presence of catecholamines at a concentration as high as 50 ng/ml. Using this method we have demonstrated the release of small amounts (2 ng/ml) of an endogenous PGE-like substance from rabbit ear vessels contracted by an infusion of norepinephrine (500 ng/ml/min).