Role of phospholipase D and diacylglycerol in activating constitutive TRPC-like cation channels in rabbit ear artery myocytes
Previously we have described a constitutively active Ca 2+ -permeable non-selective cation channel in freshly dispersed rabbit ear artery myocytes that has similar properties to canonical transient receptor potential (TRPC) channel proteins. In the present study we have investigated the transduction...
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Published in | The Journal of physiology Vol. 566; no. 3; pp. 769 - 780 |
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Main Authors | , , |
Format | Journal Article |
Language | English |
Published |
9600 Garsington Road , Oxford , OX4 2DQ , UK
The Physiological Society
01.08.2005
Blackwell Science Ltd Blackwell Science Inc |
Subjects | |
Online Access | Get full text |
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Summary: | Previously we have described a constitutively active Ca 2+ -permeable non-selective cation channel in freshly dispersed rabbit ear artery myocytes that has similar properties to canonical
transient receptor potential (TRPC) channel proteins. In the present study we have investigated the transduction pathways
responsible for stimulating constitutive channel activity in these myocytes. Application of the pharmacological inhibitors
of phosphatidylcholine-phospholipase D (PC-PLD), butan-1-ol and C2 ceramide, produced marked inhibition of constitutive channel
activity in cell-attached patches and also butan-1-ol produced pronounced suppression of resting membrane conductance measured
with whole-cell recording whereas the inactive isomer butan-2-ol had no effect on constitutive whole-cell or channel activity.
In addition butan-1-ol had no effect on channel activity evoked by the diacylglycerol (DAG) analogue 1-oleoyl-2-acetyl- sn -glycerol (OAG). Inhibitors of PC-phospholipase C (PC-PLC) and phospholipase A 2 (PLA 2 ) had no effect on constitutive channel activity. Application of a purified PC-PLD enzyme and its metabolite phosphatidic
acid to inside-out patches markedly increased channel activity. The phosphatidic acid phosphohydrolase (PAP) inhibitor dl -propranolol also inhibited constitutive and phosphatidic acid-induced increases in channel activity but had no effect on
OAG-evoked responses. The DAG lipase and DAG kinase inhibitors, RHC80267 and R59949 respectively, which inhibit DAG metabolism,
produced transient increases in channel activity which were mimicked by relatively high concentrations (40 μ m ) of OAG. The protein kinase C (PKC) inhibitor chelerythrine did not prevent channel activation by OAG but blocked the secondary
inhibitory response of OAG. It is proposed that endogenous DAG is involved in the activation of channel activity and that
its effects on channel activity are concentration-dependent with higher concentrations of DAG also inhibiting channel activity
through activation of PKC. This study indicates that constitutive cation channel activity in ear artery myocytes is mediated
by DAG which is generated by PC-PLD via phosphatidic acid which represents a novel activation pathway of cation channels in
vascular myocytes. |
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Bibliography: | ObjectType-Article-1 SourceType-Scholarly Journals-1 ObjectType-Feature-2 content type line 23 |
ISSN: | 0022-3751 1469-7793 |
DOI: | 10.1113/jphysiol.2005.090852 |