Evidence for release of prostaglandin F2 alpha in contractile response of guinea pig trachea to norepinephrine.

The concentration (10(-8)-10(-5) M)-dependent contractile response of norepinephrine was completely inhibited by cyclooxygenase inhibitors but not by a thromboxane synthetase inhibitor. The amount of prostaglandin F2 alpha was significantly increased in the presence of norepinephrine (10(-5) M). Norepinephrine increased the amount of prostaglandin D2, although not significantly. The norepinephrine-evoked prostaglandin release was inhibited by tolazoline (3 x 10(-5) M). These results suggest that norepinephrine evoked the release of prostaglandins, mainly prostaglandin F2 alpha to induce the contraction of the guinea pig trachea.