Adenosine receptors (AR) play a major role in maintaining and regulating cardiovascular function. The physiological effects of adenosine range from control of chronotropy and ionotropy to vasoregulation and the modulation of growth and migration of smooth muscle cells. Congestive heart failure is associated with decreased vasoregulatory response to adenosine and small vessel vasospasm. In this project, the investigators will characterize AR mediated transmembrane signalling in vascular smooth muscle cells (VSMC) including a delineation of which AR are present, which effector systems are utilized in signalling, how AR regulate growth and differentiation, how elevated levels of adenosine regulate these receptor systems and how these functions can be modified through creation of mutant ARs with particular emphasis on AZARs. Evidence will also be sought to determine if the newly found A2b and A3AR are present in VSMC since physiological data are consistent with their presence. Studies will be carried out in primary cultures of VSMCs, a transformed VSMC line and in CHO and COS7 cells transfected with wild type or mutant receptors. The process of desensitization will be probed in detail concerning the role of phosphorylation of the receptor, mechanisms by which the cell cycles AR and how mutation of potential regulatory sites on the AR changes the patterns of desensitization. Strong evidence exists that the A1AR can regulate multiple effector systems in VSMCs including adenylylcyclase, phospholipase C and guanylate cyclase. A2AR receptors appear to only stimulate adenylylcyclase. Evidence suggests that activation of A2ARs inhibit and A1ARs stimulate growth and DNA synthesis in VSMC. These pathways will be studied in detail and approaches to selectively differentiate pathways that lead to regulation of muscle tone such as inhibition of adenylylcyclase versus regulation of growth and DNA synthesis which may well be mediated by phospholipase C will be undertaken. Attempts to modulate growth of SMCs through transfection (infection) of mutant receptors such as constitutively active AR or dominant negative AR will be undertaken using high efficiency adenovirus vectors. The overall goal will be to understand AR mediated transmembrane signalling in VSMCs, how it is regulated and how it is possible to manipulate these pathways via recombinant DNA techniques for potential therapeutic benefit.

Agency
National Institute of Health (NIH)
Institute
National Heart, Lung, and Blood Institute (NHLBI)
Type
Specialized Center (P50)
Project #
5P50HL054314-04
Application #
6273040
Study Section
Project Start
1998-01-26
Project End
1998-12-31
Budget Start
1997-10-01
Budget End
1998-09-30
Support Year
4
Fiscal Year
1998
Total Cost
Indirect Cost
Name
Duke University
Department
Type
DUNS #
071723621
City
Durham
State
NC
Country
United States
Zip Code
27705
Dun, N J; Le Dun, S; Chen, C T et al. (2000) Orexins: a role in medullary sympathetic outflow. Regul Pept 96:65-70
Palmer, T M; Stiles, G L (2000) Identification of threonine residues controlling the agonist-dependent phosphorylation and desensitization of the rat A(3) adenosine receptor. Mol Pharmacol 57:539-45
Palmer, T M; Stiles, G L (1999) Stimulation of A(2A) adenosine receptor phosphorylation by protein kinase C activation: evidence for regulation by multiple protein kinase C isoforms. Biochemistry 38:14833-42
Brahmajothi, M V; Campbell, D L; Rasmusson, R L et al. (1999) Distinct transient outward potassium current (Ito) phenotypes and distribution of fast-inactivating potassium channel alpha subunits in ferret left ventricular myocytes. J Gen Physiol 113:581-600
Ren, H; Stiles, G L (1999) Dexamethasone stimulates human A1 adenosine receptor (A1AR) gene expression through multiple regulatory sites in promoter B. Mol Pharmacol 55:309-16
Ren, H; Stiles, G L (1998) A single-stranded DNA binding site in the human A1 adenosine receptor gene promoter. Mol Pharmacol 53:43-51
Rigolin, V H; Li, J S; Hanson, M W et al. (1997) Role of right ventricular and pulmonary functional abnormalities in limiting exercise capacity in adults with congenital heart disease. Am J Cardiol 80:315-22
Liu, S; Rasmusson, R L (1997) Hodgkin-Huxley and partially coupled inactivation models yield different voltage dependence of block. Am J Physiol 272:H2013-22
Palmer, T M; Harris, C A; Coote, J et al. (1997) Induction of multiple effects on adenylyl cyclase regulation by chronic activation of the human A3 adenosine receptor. Mol Pharmacol 52:632-40
Brahmajothi, M V; Morales, M J; Rasmusson, R L et al. (1997) Heterogeneity in K+ channel transcript expression detected in isolated ferret cardiac myocytes. Pacing Clin Electrophysiol 20:388-96

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