Effects of a toxin from the mucus of the Caribbean sea anemone (Bunodosoma granulifera) on the ionic currents of single ventricular mammalian cardiomyocytes.
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.
Salinas
E M
EM
Instituto de Fisiologia, Universidad Autónoma de Puebla, México.
Cebada
J
J
Valdés
A
A
Garateix
A
A
Aneiros
A
A
Alvarez
J L
JL
D000200:Action Potentials / Q000187:drug effects; D000818:Animals; D015220:Calcium Channels / Q000187:drug effects; D002478:Cells, Cultured; D004285:Dogs; D006321:Heart / Q000187:drug effects* / Q000502:physiology; D006352:Heart Ventricles / Q000187:drug effects; D066298:In Vitro Techniques; D007473:Ion Channels / Q000187:drug effects*; D008387:Marine Toxins / Q000302:isolation & purification / Q000494:pharmacology*; D009200:Myocardial Contraction / Q000187:drug effects*; D018408:Patch-Clamp Techniques; D015221:Potassium Channels / Q000187:drug effects; D051381:Rats; D012615:Sea Anemones / Q000737:chemistry*; D015222:Sodium Channels / Q000187:drug effects; D013268:Stimulation, Chemical; D016276:Ventricular Function
D015220:Calcium Channels; D007473:Ion Channels; D008387:Marine Toxins; D015221:Potassium Channels; D015222:Sodium Channels