EVIDENCE THAT HISTAMINE IS THE PRINCIPAL PHARMACOLOGICAL COMPONENT OFVENOM FROM AN AUSTRALIAN WOLF SPIDER (LYCOSA-GODEFFROYI)

Wolf spiders are common throughout Australia and have been known to ca use severe reactions in both animals and humans. However, little work has been done on the pharmacological activity of Australian lycosids. The purpose of this study was to obtain a preliminary pharmacological profile of the venom from an Australian wolf spider (Lycosa godeffroyi ). The venom caused dose-dependent contractions of guinea-pig isolated ileum (1-4 mu g/ml): endothelium-dependent relaxation in rat isolated aortae (10 mu g/ml), a decrease in mean arterial blood pressure in th e anaesthetised rat (100 mu g/kg, i.v.) and an increase in insufflatio n pressure in the anaesthetised guinea-pig (50 mu g/kg, i.v.). All of these responses were significantly inhibited by the HI-receptor antago nist mepyramine at concentrations that selectively inhibited responses to histamine. Venom (5 mu g/ml) caused a decrease in twitch height of the rat stimulated (0.3msec, 0.2Hz, 100V) vas deferens (prostatic seg ment). A fluorometric assay for histamine detected a concentration of 44.5 ng/mu g venom protein. It appears that the in vitro and in vivo a ctivity of L. godeffroyi venom observed in the present study is due to the presence of histamine. (C) 1998 Elsevier Science Ltd. All rights reserved.