Inhibition of Paf-acether-induced edema of the rat's paw

Three classes of drugs were found, after their i.p. administration, to inhibit Paf-acether-induced edema of the rat's paw. These were beta-adrenergic agonists (isoproterenol, salbutamol), alpha-adrenergic antagonists (prazosin, ergotamine, yohimbine, phenoxybenzamine), and calcium entry blockers (nifedipine, verapamil, diltiazem). A number of other drugs including steroidal and nonsteroidal antiinflammatory agents, alpha-agonists, beta-antagonists, pyrilamine, atropine, methysergide, a lipoxygenase inhibitor, and a leukotriene antagonist did not inhibit the development of the edema. Propranolol, but not practolol, antagonized the inhibitory effect of isoproterenol which provided evidence for involvement of beta-2 receptors in the mechanism of action of the beta agonists. It is suggested that cellular calcium influx is involved in the edemagenic response observed after the injection of Paf-acether into the rat's paw.