Effects of divalent cations on the E-4031-sensitive repolarization current, I(Kr), in rabbit ventricular myocytes.
Biophys J
; 74(3): 1278-85, 1998 Mar.
Article
in En
| MEDLINE
| ID: mdl-9512025
ABSTRACT
The effects of divalent cations on the E-4031-sensitive repolarization current (I(Kr)) were studied in single ventricular myocytes isolated from rabbit hearts. One group of divalent cations (Cd2+, Ni2+, Co2+, and Mn2+) produced a rightward shift of the I(Kr) activation curve along the voltage axis, increased the maximum I(Kr) amplitude (i.e., relieved the apparent inward rectification of the channel), and accelerated I(Kr) tail current kinetics. Another group (Ca2+, Mg2+ and Sr2+) had relatively little effect on I(Kr). The only divalent cation that blocked I(Kr) was Zn2+ (0.1-1 mM). Under steady-state conditions, Ba2+ caused a substantial block of I(K1) as previously reported. However, block by Ba2+ was time dependent, which precluded a study of Ba2+ effects on I(Kr). We conclude that the various effects of the divalent cations can be attributed to interactions with distinct sites associated with the rectification and/or inactivation mechanism of the channel.
Full text:
1
Collection:
01-internacional
Database:
MEDLINE
Main subject:
Piperidines
/
Pyridines
/
Potassium Channels
/
Cations, Divalent
/
Potassium Channels, Voltage-Gated
/
Cation Transport Proteins
/
Membrane Potentials
/
Anti-Arrhythmia Agents
Type of study:
Diagnostic_studies
Limits:
Animals
Language:
En
Journal:
Biophys J
Year:
1998
Document type:
Article
Affiliation country:
Canada