Involvement of prostaglandins in the inhibitory response of adrenoceptor agonists in the rat isolated uterus

1. The possible involvement of intramurally generated prostaglandins in the responses produced by noradrenaline (NA), adrenaline (ADR) and salbutamol (SAL) has been investigated in the rat isolated uterus. 2. NA, ADR and SAL produced concentration-related inhibition of acetylcholine-induced tone in preparations from the proestrus, oestrus, metoestrus and dioestrus phases of the oestrous cycle, and from ovariectomized animals. 3. The cyclo-oxygenase inhibitor, flurbiprofen (FBF), enhanced uterine inhibitory response to all three agonists under the different hormonal conditions. 4. The dual inhibitor of cyclo-oxygenase and lipoxygenase, 3-amino-l-(m-trifluoromethyl)-phenyl-2-pyrazolone (BW 755C) also potentiated uterine response to NA, ADR and SAL, but the effect produced by BW 755C was similar to that achieved in the presence of FBF. 5. In contrast, the inhibition elicited by histamine and papaverine were unaffected by FBF treatment. 6. The above results provide pharmacological evidence that adrenoceptor agonists may influence prostaglandin production in the rat uterus both in the presence, and absence of the ovarian hormones.