Leiurus quinquestriatus venom inhibits BRL 34915-induced 86Rb+ efflux from the rat portal vein.
The effect of the crude venom of the Israeli scorpion Leiurus quinquestriatus hebraeus on the 86Rb+ efflux stimulated by the K+ channel opener BRL 34915 in the rat portal vein was examined. Applied alone, the venom greatly increased the spontaneous mechanical activity of and the concomitant 86Rb+ efflux from the vessel. When the excitability of the vein was suppressed by the dihydropyridine calcium antagonist, PN 200-110, the 86Rb+ efflux stimulated by BRL 34915 could be shown to be inhibited by the venom. From the concentration dependence of this inhibition an IC50 value of 0.17 +/- 0.01 mg/ml was estimated. This venom is thus the most potent blocker of BRL 34915-evoked 86Rb+ efflux reported so far.
D000818:Animals; D001578:Benzopyrans / Q000037:antagonists & inhibitors / Q000494:pharmacology*; D002118:Calcium / Q000378:metabolism; D019806:Cromakalim; D004305:Dose-Response Relationship, Drug; D066298:In Vitro Techniques; D007473:Ion Channels / Q000187:drug effects; D017275:Isradipine; D010069:Oxadiazoles / Q000494:pharmacology; D011169:Portal Vein / Q000187:drug effects* / Q000378:metabolism; D011188:Potassium / Q000378:metabolism*; D011758:Pyrroles / Q000037:antagonists & inhibitors / Q000494:pharmacology*; D051381:Rats; D012414:Rubidium Radioisotopes; D012604:Scorpion Venoms / Q000494:pharmacology*; D014665:Vasodilator Agents / Q000494:pharmacology*
D001578:Benzopyrans; D007473:Ion Channels; D010069:Oxadiazoles; D011758:Pyrroles; D012414:Rubidium Radioisotopes; D012604:Scorpion Venoms; D014665:Vasodilator Agents; D019806:Cromakalim; D011188:Potassium; D002118:Calcium; D017275:Isradipine