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Differential regulation of Ca 2+ ‐activated Cl − currents in rabbit arterial and portal vein smooth muscle cells by Ca 2+ ‐calmodulin‐dependent kinase
Author(s) -
Greenwood Iain A.,
Ledoux Jonathan,
Leblanc Normand
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.1469-7793.2001.00395.x
Subject(s) - chemistry , pipette , myocyte , biophysics , intracellular , calmodulin , medicine , endocrinology , calcium , biochemistry , biology , organic chemistry
1 Ca 2+ ‐activated chloride currents ( I Cl(Ca) ) were recorded from smooth muscle cells isolated from rabbit pulmonary (PA) and coronary artery (CA) as well as rabbit portal vein (PV). The characteristics and regulation by Ca 2+ ‐calmodulin‐dependent kinase II (CaMKII) were compared between the three cell types. 2 In PA and CA myocytes dialysed and superfused with K + ‐free media, pipette solutions containing fixed levels of free Ca 2+ in the range of 250 n m to 1 μ m evoked well sustained, outwardly rectifying I Cl(Ca) currents in about 90 % of cells. The CaMKII inhibitor KN‐93 (5 μ m ) increased the amplitude of I Cl(Ca) in PA and CA myocytes. However, the threshold intracellular Ca 2+ concentration for detecting this effect was different in the two arterial cell types. KN‐93 also enhanced the rate of activation of the time‐dependent current during depolarising steps, slowed the kinetics of the tail current following repolarisation, and induced a negative shift of the steady‐state activation curve. 3 In PA myocytes, the effects of KN‐93 were not mirrored by its inactive analogue KN‐92 but were reproduced by the inclusion of autocamtide‐2‐related CaMKII inhibitory peptide (ARIP) in the pipette solution. Cell dialysis with constitutively active CaMKII (30 n m ) significantly reduced I Cl(Ca) evoked by 500 n m Ca 2+ . 4 In PV myocytes, I Cl(Ca) was evoked by pipette solutions containing up to 1 μ m free Ca 2+ in less than 40 % of cells. Application of KN‐93 to cells where I Cl(Ca) was sustained produced a small inhibition (≈25 %) of the current in 70 % of the cells. 5 The present study shows that regulation of Ca 2+ ‐dependent Cl − channels by CaMKII differs between arterial and portal vein myocytes.