Dibenzylamine--a novel blocker of the voltage-dependent K+ current in myocardial mouse cells.
Ventricular myocytes of the mouse ventricle were voltage clamped with a patch-clamp technique in the whole-cell configuration. At depolarizing voltage pulses, these myocytes develop a large voltage-dependent K+ outward current. Application of the drug dibenzylamine (DBA) to the bath solution blocked the voltage-dependent K+ current. The concentration/response relationship for the peak current at +40 mV indicates a 1:1 binding of the drug to the receptor with a concentration of half maximum effect of 43.1 micromol/l. The block did not require activation of the channels by depolarizing pulses. At concentrations causing partial block (25 micromol/l), the block was independent of voltage. At the same concentration, DBA completely blocked the slow component of the recovery from inactivation (-80 mV) whereas steady-state inactivation was not altered. It is concluded that DBA is a novel blocker of the voltage-dependent K+ current in mouse cardiac myocytes which preferentially affects the current component generating the slow recovery from inactivation.
Doepner
B
B
Institut für Physiologie der Friedrich-Schiller-Universität Jena, Abteilung Herz-Kreislauf-Physiologie, Germany.
Koopmann
R
R
Knopp
A
A
Hirche
H
H
Benndorf
K
K
D000818:Animals; D001596:Benzylamines / Q000494:pharmacology*; D002478:Cells, Cultured; D006321:Heart / Q000187:drug effects*; D006352:Heart Ventricles; D008564:Membrane Potentials / Q000187:drug effects; D051379:Mice; D009206:Myocardium / Q000378:metabolism*; D018408:Patch-Clamp Techniques; D011188:Potassium / Q000378:metabolism; D026902:Potassium Channel Blockers / Q000494:pharmacology*; D015221:Potassium Channels / Q000378:metabolism*
D001596:Benzylamines; D026902:Potassium Channel Blockers; D015221:Potassium Channels; C005051:dibenzylamine; D011188:Potassium