Cerebral circulation is exquisitely regulated, but mechanisms involved still require considerable investigation. Cerebral arteries are major resistance vessels critical for control of brain regional blood flow. Cerebral artery smooth muscle cell membrane potential controls intracellular calcium ([Ca2+]i) concentration and is a major regulator of contractility. Although several cation channels that regulate arterial smooth muscle cell membrane potential have been identified, vasoregulation by anion channels is poorly understood. In particular, the molecular identity and physiological functions of arterial smooth muscle cell chloride (Cl-) channels is unclear. Hypertension is associated with increased risk for devastating cerebral diseases, including stroke and dementia. Cerebral arteries from hypertensive subjects are depolarized, leading to elevated contractility, but involvement of Cl- channels in this pathological alteration is not known. This application derives from novel preliminary data suggesting that recently discovered transmembrane 16A Cl- (TMEM16A) channels are expressed in cerebral artery smooth muscle cells and regulate arterial contractility. We also provide novel data indicating that hypertension is associated with alterations in TMEM16A channels that elevate cerebral artery contractility.
Three specific aims will be investigated to test the central hypothesis that cerebral artery smooth muscle cell TMEM16A channels control physiological arterial contractility and alterations in TMEM16A channel regulation elevate contractility in hypertension.
Aim 1 will examine the molecular identity and regulation of TMEM16 channels expressed in arterial smooth muscle cells.
Aim 2 will elucidate the functional significance of smooth muscle cell TMEM16A channels in controlling arterial membrane potential, [Ca2+]i and contractility.
Aim 3 will explore the hypothesis that systemic hypertension is associated with an alteration in smooth muscle cell TMEM16A channels and that inhibiting myocyte TMEM16A channels in hypertension induces vasodilation. This proposal will provide significant novel information concerning cerebral artery regulation by smooth muscle cell Cl- channels and will evaluate the potential that TMEM16A channels are a new molecular target for modulating contractility.

Public Health Relevance

Arterial smooth muscle cell ion channels modulate regional blood flow in the brain, but the molecular identity of anion channels, particularly chloride channels, in smooth muscle cells is poorly understood. Pathological alterations in cerebral artery smooth muscle cell ion channels are associated with vascular diseases, including stroke and dementia, but whether chloride channels are involved is unclear. Our proposal will investigate the novel hypothesis that recently discovered TMEM16A chloride channels are expressed in cerebral artery smooth muscle cells where they regulate physiological arterial contraction, and pathological alterations in these channels elevates cerebral artery contractility in hypertension.

Agency
National Institute of Health (NIH)
Institute
National Heart, Lung, and Blood Institute (NHLBI)
Type
Research Project (R01)
Project #
3R01HL110347-03S1
Application #
8791764
Study Section
Special Emphasis Panel (ZRG1-VH-B (02))
Program Officer
Olive, Michelle
Project Start
2011-07-15
Project End
2016-06-30
Budget Start
2014-02-01
Budget End
2014-06-30
Support Year
3
Fiscal Year
2014
Total Cost
$20,861
Indirect Cost
$6,954
Name
University of Tennessee Health Science Center
Department
Physiology
Type
Schools of Medicine
DUNS #
941884009
City
Memphis
State
TN
Country
United States
Zip Code
38163
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Leo, M Dennis; Bulley, Simon; Bannister, John P et al. (2015) Angiotensin II stimulates internalization and degradation of arterial myocyte plasma membrane BK channels to induce vasoconstriction. Am J Physiol Cell Physiol 309:C392-402
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Burris, Sarah K; Wang, Qian; Bulley, Simon et al. (2015) 9-Phenanthrol inhibits recombinant and arterial myocyte TMEM16A channels. Br J Pharmacol 172:2459-68
Kidd, Michael W; Leo, M Dennis; Bannister, John P et al. (2015) Intravascular pressure enhances the abundance of functional Kv1.5 channels at the surface of arterial smooth muscle cells. Sci Signal 8:ra83
Leo, M Dennis; Bannister, John P; Narayanan, Damodaran et al. (2014) Dynamic regulation of β1 subunit trafficking controls vascular contractility. Proc Natl Acad Sci U S A 111:2361-6
Peixoto-Neves, Dieniffer; Leal-Cardoso, Jose Henrique; Jaggar, Jonathan H (2014) Eugenol dilates rat cerebral arteries by inhibiting smooth muscle cell voltage-dependent calcium channels. J Cardiovasc Pharmacol 64:401-6
Nourian, Zahra; Li, Min; Leo, M Dennis et al. (2014) Large conductance Ca2+-activated K+ channel (BKCa) α-subunit splice variants in resistance arteries from rat cerebral and skeletal muscle vasculature. PLoS One 9:e98863
Evanson, Kirk W; Bannister, John P; Leo, M Dennis et al. (2014) LRRC26 is a functional BK channel auxiliary γ subunit in arterial smooth muscle cells. Circ Res 115:423-31
Bulley, Simon; Jaggar, Jonathan H (2014) Cl⁻ channels in smooth muscle cells. Pflugers Arch 466:861-72

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