Cardiovascular Research Advance Access [Accepted Manuscript] published online on May 8, 2009
Cardiovascular Research, doi:10.1093/cvr/cvp143
Endothelin I and angiotensin II inhibit arterial voltage-gated K+ channels through different PKC isoenzymes
a Department of Cardiovascular Sciences, University of Leicester, Robert Kilpatrick Clinical Sciences Building, Leicester Royal Infirmary, Leicester, LE2 7LX
b Department of Cell Physiology and Pharmacology, University of Leicester, PO Box 138, Leicester LE1 9HN, UK
* Corresponding author: R.D. Rainbow, Department of Cardiovascular Sciences, University of Leicester, Robert Kilpatrick Clinical Sciences Building, Leicester Royal Infirmary, Leicester, LE2 7LX, Tel: 44 116 252 3185, Fax: 44 116 252 3273, Email: rdr8{at}le.ac.uk
Aims: Voltage-gated K+ channels (Kv) of arterial smooth muscle modulate arterial tone and are inhibited by vasoconstrictors through protein kinase C (PKC). We aimed to determine whether endothelin-1 (ET-1) and angiotensin II (AngII ), which cause similar inhibition of Kv, use the same signalling pathway and PKC isoenzyme to exert their effects on Kv and to compare the involvement of PKC isoenzymes in contractile responses to these agents.
Methods and results: Kv currents recorded using the patch clamp technique with freshly-isolated rat mesenteric arterial smooth muscle cells were inhibited by ET-1 or AngII. Inclusion of a PKC
inhibitor peptide in the intracellular solution substantially reduced inhibition by AngII, but did not affect that by ET-1. Kv inhibition by ET-1 was reduced by the conventional PKC inhibitor Gö6976 but not by the PKCβ inhibitor LY333531. Selective peptide inhibitors of PKC
and PKC were linked to a Tat carrier peptide to make them membrane permeable and used to show that inhibition of PKC prevented ET-1 inhibition of Kv current but did not affect that by AngII. In contrast, inhibition of PKC prevented Kv inhibition by AngII but not by ET-1. The Tat-linked inhibitor peptides were also used to investigate the involvement of PKC and in the contractile responses of mesenteric arterial rings, showing that ET-1 contractions were substantially reduced by inhibition of PKC but unaffected by inhibition of PKC. AngII contractions were unaffected by inhibition of PKC but substantially reduced by inhibition of PKC.
Conclusions: ET-1 inhibits Kv channels of mesenteric arterial smooth muscle through activation of PKC, while AngII does so through PKC. This implies that ET-1 and AngII target Kv channels of arterial smooth muscle through different pathways of PKC-interacting proteins, so each vasoconstrictor enables its distinct PKC isoenzyme to interact functionally with the Kv channel.
KEYWORDS Kv channel; endothelin; angiotensin; protein kinase C; arteries
Time for primary review: 27 Days