[An nonselective cation current in rabbit ventricle myocytes].
OBJECTIVE
Currents contributing repolarization in rabbit ventricular myocyte are very complex since the I(To.s) covers almost the whole repolarization phase of the action potential. The other components of repolarizing currents, as I(Kr) and I(Ks) are small. The purpose of this study is to investigate whether or not there are other currents in rabbit ventricular repolarization.


METHODS
Ion currents of rabbit ventricular myocyte were recorded using the whole-cell patch-clamp technique.


RESULTS
In the present work, an nonselective cation current was identified by replacing the K(+) with Cs(+) in the bathing and pipette solutions. The outward current elicited by depolarizing potentials could be inhibited by Gd(3+), an effective inhibitor of nonselective cation currents. Depleting Ca(2+) and Mg(2+) in the bathing solution, the amplitudes of this outward current increased by 40%-116% at +60 mV, and adding 2 micromol/L insulin to the solution (with normal concentration of Ca(2+) and Mg(2+) in Tyrode's solution), the amplitude increased by 30%-60% at +60 mV.


CONCLUSIONS
It is suggested that a nonselective cation current in rabbit ventricular myocytes may play an important role in the repolarization of the action potential in rabbit ventricle. Changes of nonselective cation current will lead to induce or inhibit arrhythmia.
Song
Yan-dong
YD
Emergency Center for Cardiopulmonary Disease, Beijing Anzhen Hospital, Capital University of Medical Science, 100029 Beijing, China.
Yang
Xin-chun
XC
Liu
Tai-feng
TF
Gu
Zhong-wei
ZW
D000818:Animals; D008564:Membrane Potentials; D032383:Myocytes, Cardiac / Q000502:physiology*; D018408:Patch-Clamp Techniques; D011817:Rabbits