title: Functional coupling of TRPV4, IK, and SK channels contributes to Ca(2+)-dependent endothelial injury in rodent lung.
abstract: Our previous work has shown that the increased lung endothelial permeability response to 14,15-epoxyeicosatrienoic acid (14,15-EET) in rat lung requires Ca(2+) entry via vanilloid type-4 transient receptor potential (TRPV4) channels. Recent studies suggest that activation of TRPV4 channels in systemic vascular endothelium prolongs agonist-induced hyperpolarization and amplifies Ca(2+) entry by activating Ca(2+)-activated K(+) (KCa) channels, resulting in vessel relaxation. Activation of endothelial KCa channels thus has potential to increase the electrochemical driving force for Ca(2+) influx via TRPV4 channels and to amplify permeability responses to TRPV4 activation in lung. To examine this hypothesis, we used Western blot analysis, electrophysiological recordings, and isolated-lung permeability measurements to document expression of TRPV4 and KCa channels and the potential for functional coupling. The results show that rat pulmonary microvascular endothelial cells express TRPV4 and 3 KCa channels of different conductances: large (BK), intermediate (IK), and small (SK3). However, TRPV4 channel activity modulates the IK and SK3, but not the BK, channel current density. Furthermore, the TRPV4-mediated permeability response to 14,15-EET in mouse lung is significantly attenuated by pharmacologic blockade of IK and SK3, but not BK, channels. Collectively, this functional coupling suggests that endothelial TRPV4 channels in rodent lung likely form signaling microdomains with IK and SK3 channels and that the integrated response dictates the extent of lung endothelial injury caused by 14,15-EET.
authors.affiliation: Department of Physiology and Cell Biology, University of South Alabama, Mobile, Alabama, USA ; These authors contributed equally to this work.
authors.forename: Mike T
authors.initials: MT
authors.lastname: Lin
authors.affiliation: Department of Physiology and Cell Biology, University of South Alabama, Mobile, Alabama, USA ; Center for Lung Biology, University of South Alabama, Mobile, Alabama, USA ; Present address: Department of Anesthesiology, University of Alabama at Birmingham, Birmingham, Alabama, USA. ; These authors contributed equally to this work.
authors.forename: Ming-Yuan
authors.initials: MY
authors.lastname: Jian
authors.affiliation: Department of Physiology and Cell Biology, University of South Alabama, Mobile, Alabama, USA.
authors.forename: Mark S
authors.initials: MS
authors.lastname: Taylor
authors.affiliation: Center for Lung Biology, University of South Alabama, Mobile, Alabama, USA ; Department of Biochemistry and Molecular Biology, University of South Alabama, Mobile, Alabama, USA.
authors.forename: Donna L
authors.initials: DL
authors.lastname: Cioffi
authors.affiliation: Department of Physiology and Cell Biology, University of South Alabama, Mobile, Alabama, USA.
authors.forename: Fui C
authors.initials: FC
authors.lastname: Yap
authors.affiliation: Departments of Medicine, Neurology and Neurobiology, Duke University, Durham, North Carolina, USA.
authors.forename: Wolfgang
authors.initials: W
authors.lastname: Liedtke
authors.affiliation: Department of Physiology and Cell Biology, University of South Alabama, Mobile, Alabama, USA ; Center for Lung Biology, University of South Alabama, Mobile, Alabama, USA ; Department of Medicine, University of South Alabama, Mobile, Alabama, USA.
authors.forename: Mary I
authors.initials: MI
authors.lastname: Townsley
keywords: BK; IK1; KCa; SK3; lung injury