Vascular smooth muscle (VSM) contractility, which underlies the regulation of circulation, is closely coupled to metabolism. We have shown that VSM metabolism is functionally compartmentalized, i.e., oxidative metabolism is strongly correlated with force whereas aerobic glycolysis is independently correlated with the Na-pump. Our central hypothesis is that this observed functional compartmentation is a reflection of the cytosolic compartmentation of metabolism in VSM. The testing of this hypothesis and its implications for VSM energetics, the coupling of metabolism with function and in particular, to our understanding of the mechanisms for control of VSM metabolism, forms the basis of this work. The first major goal is the elucidation of the compartmentation of glycolysis and glycogenolysis. Our studies will involve the determination of the metabolic fate of 14C from glycogen, the specific activities of glycolytic intermediates, and the mechanisms of its regulation. These studies will lead to the broader question of the nature of the substrate(s) for oxidative metabolism and its dependence on function. This will be addressed by measurement of oxygen consumption and CO2 production to establish the respiratory quotient, and, of the fate of 14C from various substrates. The second major specific aim involves elucidation of the functional compartmentation. The mechanism for the coupling of the Na-pump and aerobic glycolysis is poorly understood. Our hypothesis is that this coupling reflects the localization of a glycolytic enzyme cascade on the plasmalemma in close apposition to the Na+-K+ ATPase. This will be tested by quantitation of Na-pump function and aerobic glycolysis first in intact vessels, utilizing K+-electrodes to continuously monitor Na-pump function and high resolution fluorometric measurement of lactate. This will further be tested by cell fractionation studies including: localization and quantitation of the major oxidative and glycolytic enzymes, particularly, glycolytic enzymes in a purified plasma membrane preparation; and quantitation of Na-pump activity and glycolysis in this cell fraction. The last major specific aim involves the elucidation of the control mechanisms for coordination of metabolism with VSM function, testing the hypothesis that cyclic nucleotides and high energy phosphates, both likely metabolic regulators, are compartmentalized. Studies will include the correlation of the activities of cAMP-dependent protein kinases with the functional compartmentation, localization of these enzymes, determination of the role of cAMP in coordinating glycolysis and Na-pump function in purified plasma membranes, and isotachophoretic measurement of the tissue phosphagen and metabolites under various functional loading conditions. Coronary and carotid arteries will be the major vessels studied with the long term goal of relating metabolism to normal VSM function in order to detect and characterize the mechanisms underlying vascular disease.

Agency
National Institute of Health (NIH)
Institute
National Heart, Lung, and Blood Institute (NHLBI)
Type
Research Project (R01)
Project #
5R01HL023240-11
Application #
3337195
Study Section
Physiology Study Section (PHY)
Project Start
1978-07-01
Project End
1991-06-30
Budget Start
1989-07-01
Budget End
1990-06-30
Support Year
11
Fiscal Year
1989
Total Cost
Indirect Cost
Name
University of Cincinnati
Department
Type
Schools of Medicine
DUNS #
City
Cincinnati
State
OH
Country
United States
Zip Code
45221
Szymanski, P T; Ferguson, D G; Paul, R J (2002) Polylysine binding to unphosphorylated smooth muscle myosin enhances formation and stabilizes myosin filaments in vitro. Acta Physiol Scand 174:337-46
Shimizu, S; Bowman, P S; Thorne 3rd, G et al. (2000) Effects of hypoxia on isometric force, intracellular Ca(2+), pH, and energetics in porcine coronary artery. Circ Res 86:862-70
Shimizu, S; Paul, R J (1999) Hypoxia and alkalinization inhibit endothelium-derived nitric oxide but not endothelium-derived hyperpolarizing factor responses in porcine coronary artery. J Pharmacol Exp Ther 291:335-44
Tosun, M; Paul, R J; Rapoport, R M (1998) Role of extracellular Ca++ influx via L-type and non-L-type Ca++ channels in thromboxane A2 receptor-mediated contraction in rat aorta. J Pharmacol Exp Ther 284:921-8
Liu, L H; Paul, R J; Sutliff, R L et al. (1997) Defective endothelium-dependent relaxation of vascular smooth muscle and endothelial cell Ca2+ signaling in mice lacking sarco(endo)plasmic reticulum Ca2+-ATPase isoform 3. J Biol Chem 272:30538-45
Lorenz, J N; Paul, R J (1997) Dependence of Ca2+ channel currents on endogenous and exogenous sources of ATP in portal vein smooth muscle. Am J Physiol 272:H987-94
Shimizu, S; Shimizu, K; Paul, R J (1997) Cold storage induces an endothelium-independent relaxation to hypoxia/reoxygenation in porcine coronary arteries. J Vasc Res 34:399-407
Obara, K; Bowman, P S; Ishida, Y et al. (1997) Effects of hypoxia on [Ca2+]i, pHi and myosin light chain phosphorylation in guinea-pig taenia caeci. J Physiol 503 ( Pt 2):427-33
Shimizu, S; Paul, R J (1997) The endothelium-dependent, substance P relaxation of porcine coronary arteries resistant to nitric oxide synthesis inhibition is partially mediated by 4-aminopyridine-sensitive voltage-dependent K+ channels. Endothelium 5:287-95
Tosun, M; Paul, R J; Rapoport, R M (1997) Intracellular Ca2+ elevation and contraction due to prostaglandin F2alpha in rat aorta. Eur J Pharmacol 340:203-8

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