ABSTRACT
We studied the effects of BgK toxin on outward K(+) currents in isolated neurons of the snail Helix aspersa, using the whole cell patch clamp technique. BgK partially and reversibly blocked K(+) currents in the 1 pM to 100 nM concentration range (n=53). The dose-response curve for BgK current inhibition had a maximum blocking effect at 100 nM. Our results indicate that BgK is a potent, apparently non-selective, K(+) channel blocker in molluscan neurons.
Subject(s)
Cnidarian Venoms/pharmacology , Neurons/chemistry , Neurons/physiology , Potassium Channel Blockers , Animals , Dose-Response Relationship, Drug , Helix, Snails , Membrane Potentials/drug effects , Patch-Clamp Techniques , Potassium/metabolism , Potassium Channels/physiology , Sea AnemonesABSTRACT
The effects were studied of a toxin (Bainh) isolated from the secretion of the Caribbean sea anemone Bunodosoma granulifera on electrical and mechanical activities of rat ventricular muscle. The effects on the ionic currents of single rat and dog ventricular cardiomyocytes were studied using the whole-cell recording patch-clamp technique. In the concentration range from 1 to 10 mg/ml, Bainh increased the force of contraction and induced an increase in action potential duration of ventricular multicellular preparations. In single cardiomyocytes, at concentrations up to 10 mg/ml Bainh showed no significant effects on the sodium current. However, at 0.5-1 mg/ml it increased the L-type Ca current (ICaL) by 25-50%. This increase in ICaL was not voltage dependent and was reversible after washout. The transient outward current was not significantly affected by Bainh (1-10 mg/ml). In this concentration range, Bainh markedly (approximately 75%) increased the inward-going rectifier current, IKI. This effect that was not voltage dependent and was fully reversible upon returning to control solution. It is suggested that these effects on ionic currents could explain the positive inotropic action of Bainh on cardiac multicellular preparations.
