Summary
The toxic fraction PhTx2 of the spider Phoneutria nigriventer was studied with a modified loose patch clamp technique on frog skeletal muscle. At saturating concentration (8 μg/ml) potassium currents were unaffected whereas there was a 7-fold increase in the time constant of sodium current inactivation (at −13 mV test potential). The time course of tail current deactivation was at least 3-fold slower than the control. The steady state (100 ms) inactivation and the conductance activation were shifted toward more negative potentials by 12.2 and 7.0 mV, respectively. The reversal of the sodium current was shifted 7.6 mV to more negative potential. We conclude that PhTx2 prolongs the inactivation and deactivation processes of sodium ion channels. These effects may account for the toxicity of PhTx2.
This is a preview of subscription content, log in via an institution to check access.
Similar content being viewed by others
References
Almers W, Stanfield PR, Stühmer W (1983) Lateral distribution of sodium and potassium channels in frog skeletal muscle: measurements with a patch-clamp technique. J Physiol (Lond) 336:261–284
Barrio A (1955) Spastic action of the venom of the spider Phoneutria fera. Acta Physiol Latino Americana 5:132–143
Brazil V, Vellard J (1925) Contribuição ao estudo do veneno das aranhas. Mem Inst Butantan 2:1–70
Campbell DT, Hille B (1976) Kinetic and pharmacological properties of the sodium channel of frog skeletal muscle. J Gen Physiol 67:309–323
Fontana MD, Brazil OV (1985) Mode of action of Phoneutria nigriventer spider venom at the isolated phrenic nerve diaphragm of the rat. Brazilian J Med Biol Res 18:557–565
Gillespie JI, Hutter OF (1975) The actions of 4-aminopyridine on the delayed potassium current in skeletal muscle fibres. J Physiol (Lond) 252:70P
Gonoi T, Hille B (1987) Gating of Na channels. Inactivation modifiers discriminate among models. J Gen Physiol 89:253–274
Jackson H, Parks T (1989) Spider toxins: recent applications in neurobiology. Ann Rev Neurosci 12:405–414
Kawai N, Miwa A, Shimakazi K, Sahara Y, Robinson HPC, Nakajima T (1991) Spider toxin and the glutamate receptors. Comp Biochem Physiol 98C:87–95
Rezende Jr. L, Cordeiro MN, Oliveira EB, Diniz CR (1991) Isolation of neurotoxic peptides from the venom of the ‘armed’ spider Phoneutria nigriventer. Toxicon 29:1225–1233
Roberts WM, Almers W (1984) An improved loose patch voltage clamp method using concentric pipettes. Pflügers Arch 402:190–196
Schenberg S, Pereira-Lima FA (1971) Phoneutria nigriventer venom In: Bucherl W, Bukley EE (eds) Venomous animals and their venoms, vol 3. Academic Press, New York, pp 279–297
Stühmer W, Roberts WM, Almers W (1983) The loose patch clamp. In: Sakmann B, Neher E (eds) Single channel recording. Plenum Press, New York, pp 123–132
Author information
Authors and Affiliations
Additional information
Recipient of a Doctoral Fellowship from the Universidade Federal de Alagoas
Correspondence to P. S. L. Beirão at the above address
Rights and permissions
About this article
Cite this article
Arújo, D.A.M., Cordeiro, M.N., Diniz, C.R. et al. Effects of a toxic fraction, PhTx2, from the spider Phoneutria nikriventer on the sodium current. Naunyn-Schmiedeberg's Arch Pharmacol 347, 205–208 (1993). https://doi.org/10.1007/BF00169268
Received:
Accepted:
Issue Date:
DOI: https://doi.org/10.1007/BF00169268