The biological activities of phthalate esters on rat gastric muscle

Monoethylhexyl phthalate, at concentrations that can occur in blood stored in plastic bags (0.1-0.5 mg/ml), reduced contractions of rat isolated gastric fundus to PGE2 and acetylcholine; the diethyl compound was less effective. In contrast, dibutyl phthalate (1 and 10 micrograms/ml) and, to a lesser extent di-isobutyl phthalate, increased the muscle tone. These results are discussed in relation to blood transfusion, and to structural similarities between phthalates and prostaglandins.