In vitro effect of prostaglandine F2alpha on the motility of the myometrium. Interactions with adrenergic and cholinergic receptors.

The in vitro effects of prostaglandine F2alpha(PGF2alpha) on the spontaneous contractile activity of the myometrium of rat, guinea-pig and rabbit and its interactions with adrenergic and cholinergic receptors were studied. All animals were with oestrogen domination. One myometral strip of each animal species was placed under identical conditions in a common bath with Krebbs solution. Each strip was connected to a strain gauge for the recording of the contractile activity. L-Noradrenaline (N) and Adrenaline (A) in doses of 10(-6) g/ml inhibit the contractile activity of rat myometrium (stimulation of the beta-receptors) and this effect is antagonized by beta-blocking agents. Conversely, N and A stimulate the myometrium of guinea-pigs and rabbits (stimulation of the alpha-receptors) and this effect is antagonized by the alpha-blocking agents. Unlike N and A, PGF2alpha stimulates the contractile myometral activity in all three species and its effect is not antagonized either by adrenergic or by cholinergic blocking agents. The stimulating effect of PGF2alpha antagonizes the inhibitory effect of N and A on rat myometrium and potentiates their stimulating effect on the myometrium of guinea-pigs and rabbits with a noncompetitive mechanism.