The smooth muscle relaxant effects of venom from the inland taipan (Oxyuranus microlepidotus)

摘要

Venom (10 #mu#g/ml) relaxed phenylephrine-precontracted aortae. This relaxation was unaffected by removal of the endothelium or a combination of N~g -nitro-L-arginine (L-NOARG; 0.1 mM), oxyhaemoglobin (10 #mu#M) and indomethacin (10 #mu#M). 4-BPB (0.78 mM), propranolol (1 #mu#M), or a combination of apamin (0.1 #mu#M), charybdotoxin (0.1 #mu#M) and glibenclamide (10 #mu#M) did not effect endothelium-independent relaxation, suggesting a lack of PLA_2 activity or an effect at #beta#-adrenoceptors or K~+ channels. Venom (10 #mu#g/ml) reversed Bay K 8644 (0.1 #mu#M)-induced contraction indicating the venom may have an effect on L-type Ca~(2+) channels.