Mechanism of relaxant action of prostaglandin F2alpha on the guinea-pig isolated trachea.

Prostaglandin F2alpha consistently produced a dose-related triphasic response in guinea-pig isolated tracheal chain preparations. The response consisted of an initial transient contraction followed by a transient relaxation, followed by a further contraction. The relaxant action was not due to adrenergic or histaminergic transmission, but might be due to a PG-like material released by the PGF 2alpha-induced contraction.