Some effects of the venom of the Chilean spider Latrodectus mactans on endogenous ion-currents of Xenopus laevis oocytes.
A study was made of the effects of the venom of the Chilean spider Latrodectus mactans on endogenous ion-currents of Xenopus laevis oocytes. 1 microg/ml of the venom made the resting plasma membrane potential more negative in cells voltage-clamped at -60 mV. The effect was potentially due to the closure of one or several conductances that were investigated further. Thus, we determined the effects of the venom on the following endogenous ionic-currents: (a) voltage-activated potassium currents, (b) voltage-activated chloride-currents, and (c) calcium-dependent chloride-currents (Tout). The results suggest that the venom exerts its action mainly on a transient outward potassium-current that is probably mediated by a Kv channel homologous to shaker. Consistent with the electrophysiological evidence we detected the expression of the mRNA coding for xKv1.1 in the oocytes.
Parodi
Jorge
J
Laboratorio de Neurociencias-CEBIOR, Departamento de Ciencias Preclínicas, Facultad de Medicina, Universidad de la Frontera, Av. Francisco Salazar 01145, P.O. Box 54-D, Temuco, Chile. jparodi@ufro.cl
Romero
Fernando
F
Miledi
Ricardo
R
Martínez-Torres
Ataúlfo
A
D000818:Animals; D001740:Black Widow Spider; D002118:Calcium / Q000378:metabolism; D002712:Chlorides / Q000378:metabolism; D051662:Kv1.1 Potassium Channel / Q000235:genetics / Q000378:metabolism*; D009865:Oocytes / Q000187:drug effects* / Q000378:metabolism / Q000502:physiology; D011188:Potassium / Q000378:metabolism; D012333:RNA, Messenger / Q000378:metabolism; D013111:Spider Venoms / Q000494:pharmacology*; D029867:Xenopus Proteins / Q000235:genetics / Q000378:metabolism*; D014982:Xenopus laevis
D002712:Chlorides; D012333:RNA, Messenger; D013111:Spider Venoms; D029867:Xenopus Proteins; C084069:kcna1 protein, Xenopus; D051662:Kv1.1 Potassium Channel; D011188:Potassium; D002118:Calcium