Portal de Periódicos da CAPES

The influence of the rate of electrical stimulation on the effects of the Anemonia sulcata toxin ATX II in guinea pig papillary muscle

1982; Elsevier BV; Volume: 79; Issue: 3-4 Linguagem: Inglês

10.1016/0014-2999(82)90632-x

1879-0712

László Béress, Reni Ritter, Ursula Ravens,

Ion channel regulation and function

In guinea pig papillary muscle, the rate of electrical stimulation (0.1–2 Hz) strongly influenced the effects of the Anemonia sulcata toxin ATX II on action potential duration (APD) and contractile force. In the concentration range studied (10−8−10−7 M), ATX II always produced a larger prolongation in APD at low rates of stimulation. At 0.1 Hz there was a temporal dissociation between the onset of the APD-prolonging and the positive inotropic effect. However, under equilibrium conditions there was a positive relationship between the APD expressed as a fraction of the time during which the membrane was depolarized, and the contractile force irrespective of the change in experimental conditions being variation in stimulation frequency or the addition of ATX II. The results suggest that the positive inotropic effects of both ATX II and increased stimulation frequency could be induced by a similar mechanism, e.g. an increase in sodium load of the heart muscle.