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Endothelin‐1 activates a Ca 2+ ‐permeable cation channel with TRPC3 and TRPC7 properties in rabbit coronary artery myocytes
Author(s) -
PeppiattWildman C. M.,
Albert A. P.,
Saleh S. N.,
Large W. A.
Publication year - 2007
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 - 10.1113/jphysiol.2006.126656
Subject(s) - trpc3 , chelerythrine , chemistry , phospholipase c , biophysics , trpc1 , extracellular , myocyte , flufenamic acid , trpc , protein kinase c , trpc6 , reversal potential , diacylglycerol kinase , medicine , endocrinology , transient receptor potential channel , biochemistry , biology , patch clamp , kinase , receptor
In the present work we used patch pipette techniques to study the properties of a novel Ca 2+ ‐permeable cation channel activated by the potent coronary vasoconstrictor endothelin‐1 (ET‐1) in freshly dispersed rabbit coronary artery myocytes. With cell‐attached recording bath application of 10 n m ET‐1 evoked cation channel currents ( I cat ) with subconductance states of about 18, 34 and 51 and 68 pS, and a reversal potential of 0 mV. ET‐1 evoked channel activity when extracellular Ca 2+ was the charge carrier, illustrating significant Ca 2+ permeability. ET‐1‐induced responses were inhibited by the ET A receptor antagonist BQ123 and the phospholipase C (PLC) inhibitor U73122. The diacylglycerol analogue 1‐oleoyl‐2‐acetyl‐ sn ‐glycerol (OAG) also stimulated I cat , but the protein kinase C (PKC) inhibitor chelerythrine did not inhibit either the OAG‐ or ET‐1‐induced I cat . Inositol 1,4,5‐trisphosphate (IP 3 ) did not activate I cat , but greatly potentiated the response to OAG and this effect was blocked by heparin. Bath application of anti‐TRPC3 and anti‐TRPC7 antibodies to inside‐out patches markedly inhibited ET‐1‐evoked I cat , but antibodies to TRPC1, C4, C5 and C6 had no effect. Immunocytochemical studies demonstrated preferential TRPC7 expression in the plasmalemma, whereas TRPC3 was distributed throughout the myocyte, and moreover co‐localization of TRPC3 and TRPC7 signals was observed at, or close to, the plasma membrane. Flufenamic acid, Gd 3+ , La 3+ and extracellular Ca 2+ inhibited I cat with IC 50 values of 2.45 μ m , 3.8 μ m , 7.36 μ m and 22 μ m , respectively. These results suggest that in rabbit coronary artery myocytes ET‐1 evokes a Ca 2+ ‐permeable non‐selective cation channel with properties similar to TRPC3 and TRPC7, and indicates that these proteins may be important components of this conductance.