Pharmacological investigation of oedema induced by venom from the wasp Polistes fuscatus.

Subplantar injection of Polistes fuscatus venom induced dose-dependent rat hindpaw oedema. The oedema was significant in the first hour and reached maximum size in the fifth hour after injection of the venom (20-600 micrograms/paw). Low doses of the venom (20-80 micrograms/paw) produced oedema which disappeared within 48 hr after injection, while at doses of 300-600 micrograms/paw, oedema was present in excess of 48 hr. Pharmacological studies suggested that P. fuscatus venom-induced oedema probably has a mechanism which is multimediated. Pretreatment of rats with a combination of cyproheptadine (5 mg/kg)-captopril (2 mg/kg)-dexamethasone (1 mg/kg) inhibited the formation of oedema (maximal swelling) produced by the venom (300 micrograms/paw) by about 79% and improved the time to recovery. Paw swellings caused by 20 and 40 micrograms/paw venom were completely eliminated by the same doses of this drug combination. The kinins, autacoids (histamine and serotonin) and lipogenase derivatives are probably involved in the venom-induced oedema.