Effects of lemakalim and thalium on early afterdepolarization in mouse atrial fibers.
The effects of lemakalim (BRL 38227) and thallium ion (Tl) on action potential (AP) and on early afterdepolarization (EAD) were studied in mouse atrial fibers. Under treatment with lemakalim (25 mcM) or Tl (0.2 mM), the AP was not significantly changed except for the reduction of duration of AP (APD). EAD induced by 3.0 mM K superfusion was abolished by 50 mcM lemakalim and only partially inhibited or was not effected under 25 mcM lemakalim. However, EAD was abolished completely and rapidly by Tl treatment. With addition of K concentration in superfusate to 5.0 mM the EAD could only be partially inhibited. By further increasing the K concentration to 7.0 mM the EAD could be completely abolished. It is suggested that the activator of outward current could inhibit EAD as well as the blockers of inward currents.
Chen
X J
XJ
Department of Biology, Peking University, Beijing, China.
Liu
T F
TF
Liu
K Q
KQ
D000200:Action Potentials / Q000187:drug effects; D000818:Animals; D001578:Benzopyrans / Q000494:pharmacology*; D019806:Cromakalim; D004594:Electrophysiology; D005260:Female; D006325:Heart Atria / Q000187:drug effects*; D066298:In Vitro Techniques; D008297:Male; D051379:Mice; D011188:Potassium / Q000494:pharmacology; D015221:Potassium Channels / Q000187:drug effects*; D011758:Pyrroles / Q000494:pharmacology*; D013793:Thallium / Q000494:pharmacology*
D001578:Benzopyrans; D015221:Potassium Channels; D011758:Pyrroles; D019806:Cromakalim; D013793:Thallium; D011188:Potassium