Arterial diameter, a principal modulator of systemic blood pressure and organ blood flow is regulated by changes in the contractility of arterial myocytes. The contractile status of arterial myocytes is determined by several local and global intracellular calcium([Ca2+]i) signals. Ca2+ signal and diameter regulation byinositol 1,4,5-trisphophate (IPS), a phospholipase C-generated second messenger is poorly understood. The conventional view has been that IPS constricts arteries by stimulatingsarcoplasmic reticulum(SR) Ca2+ release in myocytes. Our recently published data indicateda novel mechanism of IPS-induced vasoconstriction that occurred independentlyof SRCa2+ release, and via IPS receptor (IP3R)-and canonicaltransient receptor potential (TRPC) 3-dependent cation current (ICat) activation.However, mechanisms by which IP3R activation stimulates TRPC channelsin arterial myocytes to regulate arterial diameter are unclear. Preliminary data suggest that physical couplingbetween myocyte IPSRs and TRPC3 channels regulates IPS-induced vasoconstriction. Data also indicate that arterial myocyte caveolae facilitate this IP3R-TRPCchannel vasoregulatory mechanism. The central hypothesis ofthis proposal is that in cerebral artery myocytes, caveolae facilitate TRPC3 channel couplingwith IPSRs to mediate vasoconstrictor and IPS-induced membrane depolarization, voltage-dependent Ca2+ channel activation, [Ca2+]i elevation, and contraction. This proposal will investigate 3 specific aims:
Aim 1 will test the hypothesis that in cerebral artery myocytes, IP3R to TRPC3 channel physical couplingis required for IPS-inducedICat activation.
Aim 2 will test the hypothesis that IP3R to TRPC3 couplingmediates IPS-induced membrane depolarization, [Ca2+]i elevation, and constriction in cerebral arteries.
Aim 3 will examine the hypothesis that arterial myocyte caveolae mediate physical and functional coupling of TRPC3 channelsto IPSRs. Experiments to study these aims will integrate techniques performed at molecular, cellular,and intact tissue levels, including Ca2+ imaging,FRET, electrophysiology, pressurized artery myography, and gene suppression.

Public Health Relevance

Mechanisms that regulate blood pressure and flow are incompletely understood. Alterations in arterial contractility are associated with vascular diseases, including stroke and hypertension. This proposal will enhance our knowledge of a novel signaling event that modulates arterial contractility, and will ultimately lead to better insights into alterations that occur in vascular disease.

Agency
National Institute of Health (NIH)
Institute
National Heart, Lung, and Blood Institute (NHLBI)
Type
Research Scientist Development Award - Research & Training (K01)
Project #
5K01HL096411-02
Application #
7804568
Study Section
Special Emphasis Panel (ZHL1-CSR-R (F2))
Program Officer
Meadows, Tawanna
Project Start
2009-04-15
Project End
2014-03-31
Budget Start
2010-04-01
Budget End
2011-03-31
Support Year
2
Fiscal Year
2010
Total Cost
$114,256
Indirect Cost
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
Adebiyi, Adebowale (2014) RGS2 regulates urotensin II-induced intracellular Ca2+ elevation and contraction in glomerular mesangial cells. J Cell Physiol 229:502-11
Narayanan, Damodaran; Adebiyi, Adebowale; Jaggar, Jonathan H (2012) Inositol trisphosphate receptors in smooth muscle cells. Am J Physiol Heart Circ Physiol 302:H2190-210
Adebiyi, Adebowale; Thomas-Gatewood, Candice M; Leo, M Dennis et al. (2012) An elevation in physical coupling of type 1 inositol 1,4,5-trisphosphate (IP3) receptors to transient receptor potential 3 (TRPC3) channels constricts mesenteric arteries in genetic hypertension. Hypertension 60:1213-9
Adebiyi, Adebowale; Narayanan, Damodaran; Jaggar, Jonathan H (2011) Caveolin-1 assembles type 1 inositol 1,4,5-trisphosphate receptors and canonical transient receptor potential 3 channels into a functional signaling complex in arterial smooth muscle cells. J Biol Chem 286:4341-8
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