Stonefish (Synanceia spp.) antivenom neutralises the in vitro and in vivo cardiovascular activity of soldierfish (Gymnapistes marmoratus) venom

The soldierfish (Gymnapistes marmoratus), which is related to the stonefish (Synanceia spp.), inhabits the western, southern and lower eastern coastli nes of Australia. We have previously found that G. marmoratus venom possess es pharmacological activity similar to Synanceia trachynis venom (Hopkins, B.J., Hodgson, W.C., 1998. Cardiovascular studies on venom from the soldier fish (Gymnapistes marmoratus). Toxicon 36, 973-872; Church, J.E., Hodgson, W.C., 2000. Dose-dependent cardiovascular and neuromuscular effects of ston efish (Synanceja trachynis) venom. Toxicon 38, 391-407), namely an action a t muscarinic receptors and adrenoceptors. The aim of this study was to dete rmine the effectiveness of Synanceia antivenom in neutralising the in vitro and in vivo cardiovascular activity of G. marmoratus venom. Venom extract (0.4-12 mu g protein/ml) caused dose- and endothelium-dependent relaxation in porcine U46619-precontracted coronary arteries. This relaxation was abol ished by 10 min prior exposure of the tissue to Synanceia antivenom (3 unit s/ml). In rat paced (5 ms, 2 Hz, 7-12 V) left atria, G. marmoratus venom ex tract (40 mu g protein/ml) produced a transient negative, followed by a sus tained positive inotropic response. In spontaneously beating right atria, v enom extract (40 mu g protein/ml) produced similar changes in rate. Prior i ncubation of venom extract with Synanceia antivenom (1 unit/4 mu g venom ex tract protein, 10 min) significantly attenuated both components of the inot ropic response, and abolished the positive chronotropic response. In the an aesthetised rat, venom extract (400 mu g protein/kg, i.v.) produced a trans ient depressor response, followed by a more sustained presser response. Pri or incubation of venom extract with Synanceia antivenom (1 unit/4 mu g veno m extract protein, 10 min) significantly attenuated both components of the in vivo response. As Synanceia antivenom neutralised the cardiovascular act ivity of G. marmoratus venom both in vitro and in vivo, we suggest that the venoms of the two species may share a similar component(s). (C) 2000 Elsev ier Science Ltd. All rights reserved.