Premium
Heterogeneous expression of the delayed‐rectifier K + currents i K,r and i K,s in rabbit sinoatrial node cells
Author(s) -
Lei M.,
Honjo H.,
Kodama I.,
Boyett M. R.
Publication year - 2001
Publication title -
the journal of physiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.802
H-Index - 240
eISSN - 1469-7793
pISSN - 0022-3751
DOI - 10.1111/j.1469-7793.2001.t01-1-00703.x
Subject(s) - sinoatrial node , chemistry , biophysics , capacitance , patch clamp , medicine , receptor , electrode , biology , biochemistry , heart rate , blood pressure
1 The electrical activity of sinoatrial node cells is heterogeneous. To understand the reasons for this, the density of the delayed‐rectifier K + current and its two components, i K,r and i K,s , as a function of the size (as measured by cell capacitance) of rabbit sinoatrial node cells was investigated using the whole‐cell voltage‐clamp technique at 35 °C. 2 iK,r and i K,s were isolated using E‐4031 and 293B. Features of the E‐4031‐sensitive and 293B‐insensitive currents corresponded well to those of i K,r , while features of the E‐4031‐insensitive and 293B‐sensitive currents corresponded well to those of i K,s . 3 The densities of the outward current under control conditions and the drug‐sensitive and ‐insensitive currents were significantly ( P < 0.01) correlated with cell capacitance, with current densities being greater in larger cells. 4 The effects of partial blockade of i K,r by 0.1 μ m E‐4031 on spontaneous action potentials were greater in smaller cells. 5 It is concluded that there are cell size‐dependent differences in the density of the i K,r and i K,s components, and these may be involved in the heterogeneity of the electrical activity of single sinoatrial node cells as well as that of the intact sinoatrial node.