Continuous monitoring of prostacyclin production by the isolated, intact, rat aorta using a bioassay technique

Abstract

Isolated rat aortae were perfused with Krebs buffer in vitro and the synthesis of prostacyclin-like material (PGI 2-L) was continuously monitored by measuring the contraction of a superperfused rat stomach strip exposed to the aortic perfusate. PGI 2-L release was high after initiation of the aorta perfusion but then gradually declined and stabilized at a basal rate of production that was maintained for at least 180 min. Levels of 6 keto prostaglandin F 1α(6ketoPGF 1α), the stable breakdown product of PGI 2, in the aortic perfusate reflected the changes in biological activity. The concentration of PGE 2 in the aortic perfusate remained constant throughout the experiment while the level of thromboxane (Tx)B 2 (the stable product of TxA 2) decreased with time to below the level of detection of the radioimmunoassay (RIA) used. All biological activity was abolished by heating the aortic perfusate for 30 min at 37°C, while perfusing with 30 μM indomethacin inhibited aorta PGI-L formation. Analysis (by linear regression) of the relationship between PGI 2-L formation and the body weight or age of the animals used revealed that PGI 2-L synthesis was better related to body weight ( r 2 = 0.90) than age ( r 2 = 0.75).