毒液
克氏原螯虾
粘菌毒素
蝎子
蝎子毒
小龙虾
蝎子毒素
通道阻滞剂
解剖
毒素
生物
药理学
钾通道
生物物理学
医学
内科学
生物化学
生态学
钙
作者
Christian Legros,Marie-France Martin-Eauclaire,Daniel Cattaert
标识
DOI:10.1242/jeb.201.18.2625
摘要
ABSTRACT The resistance of the scorpion Androctonus australis to its own venom, as well as to the venom of other species, was investigated. A comparison of the electrical and pharmacological properties of muscle and nerve fibres from Androctonus australis with those from the crayfish Procambarus clarkii enabled us to understand the lack of effect of scorpion venom (110–180 μg ml−1) and purified toxins, which are active on voltage-gated Na+ and K+ channels, Ca2+-activated K+ channels, on scorpion tissues. Voltage-clamp experiments showed that peptide K+ channel blockers from scorpion and snake have no effect on currents in muscle and nerve fibres from either scorpions or crayfish. The scorpion toxin kaliotoxin (KTX), a specific blocker of Kv1.1 and Kv1.3 K+ channels, had no effect on muscle fibres of A. australis (2 μmol l−1) or P. clarkii (400 nmol l−1). Similarly, charybdotoxin (ChTX) had no effect on the muscle fibres of A. australis (10 μmol l−1) or P. clarkii (200 nmol l−1) and neither did the snake toxin dendrotoxin (DTX) at concentrations of 100 nmol l−1 in A. australis and 200 nmol l−1 in P. clarkii. These three toxins (KTX, ChTX and DTX) did not block K+ currents recorded from nerve fibres in P. clarkii. The pharmacology of the K+ channels in these two arthropods did not conform to that previously described for K+ channels in other species. Current-clamp experiments clearly indicated that the venom of A. australis (50 μg ml−1) had no effect on the shape of the action potential recorded from nerve cord axons from A. australis. At a concentration of 50 μg ml−1, A. australis venom greatly prolonged the action potential in the crayfish giant axon. The absence of any effect of the anti-mammal α-toxin AaH II (100 nmol l−1) and the anti-insect toxin AaH IT1 (100 nmol l−1) on scorpion nerve fibres revealed strong pharmacological differences between the voltage-gated Na+ channels of scorpion and crayfish. We conclude that the venom from A. australis is pharmacologically inactive on K+ channels and on voltage-sensitive Na+ channels from this scorpion.
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