Studies are proposed of synaptic events at neuroeffector junctions in pulmonary artery and in segments of the systemic vasculature from dogs. Our previous work showed that during electrical stimulation norepinephrine (NE) removal from the junctional cleft was facilitated in the saphenous vein but not in the pulmonary artery. Although we originally postulated that the facilitated NE removal was due to activation of membrane-bound catechol methyltransferase, our studies did not confirm this hypothesis. Studies are now proposed to determine whether other processes involved in clearing the synaptic cleft of NE (neuronal and extraneuronal uptakes and monoamine oxidase) can explain the enhanced removal of NE from the synaptic cleft. In addition, physiological studies will examine NE dynamics and contractile tensions in pulmonary artery having undergone changes in anatomical structure caused by chronic hypoxia. Light and electron microscopy studies will attempt to correlate synaptic cleft width with changes in NE dynamics, of particular interest will be whether the cleft width can change during pathological states such as pulmonary hypertension. Included in the proposal are also studies that will determine the effects of general anesthetic agents on neuroeffector junction function in pulmonary artery. Techniques to be used include: superfusion of isolated, helically cut strips of vessels from dogs; electrical stimulation of postganglionic nerves in these vessels; measurement of endogenous NE in tissue and in superfusate by liquid chromatography with electrochemical detection; and labeling of NE stores with [H3]NE and measurement of radiolabeled NE and its metabolites. These studies are important because changes in anatomical structure in pulmonary vasculature precede the development of pulmonary hypertension and changes in NE dynamics at structurally altered neuroeffector junctions may contribute to this hypertension. An understanding of these altered events may open new avenues of therapy directed at pulmonary hypertension.

Agency
National Institute of Health (NIH)
Institute
National Heart, Lung, and Blood Institute (NHLBI)
Type
Research Project (R01)
Project #
5R01HL023217-08
Application #
3337182
Study Section
Respiratory and Applied Physiology Study Section (RAP)
Project Start
1979-08-01
Project End
1987-07-31
Budget Start
1986-08-01
Budget End
1987-07-31
Support Year
8
Fiscal Year
1986
Total Cost
Indirect Cost
Name
Mayo Clinic, Rochester
Department
Type
DUNS #
City
Rochester
State
MN
Country
United States
Zip Code
55905
Tyce, G M; Hunter, L W; Ward, L E et al. (1995) Effluxes of 3,4-dihydroxyphenylalanine, 3,4-dihydroxyphenylglycol, and norepinephrine from four blood vessels during basal conditions and during nerve stimulation. J Neurochem 64:833-41
Brown, D L; Rorie, D K (1994) Altered reactivity of isolated segmental lumbar arteries of dogs following exposure to ethanol and phenol. Pain 56:139-43
Kamath, G S; Rorie, D K; Tyce, G M (1993) Altered release and metabolism of norepinephrine in superfused canine saphenous veins in the presence of halothane and hypoxia. Anesthesiology 78:553-61
Hunter, L W; Rorie, D K; Tyce, G M (1993) Inhibition of aromatic L-amino acid decarboxylase under physiological conditions: optimization of 3-hydroxybenzylhydrazine concentration to prevent concurrent inhibition of monoamine oxidase. Biochem Pharmacol 45:1363-6
Hughes, J M; Sill, J C; Pettis, M et al. (1993) Nitrous oxide constricts epicardial coronary arteries in pigs: evidence suggesting inhibitory effects on the endothelium. Anesth Analg 77:232-40
Hunter, L W; Rorie, D K; Tyce, G M (1992) Dihydroxyphenylalanine and dopamine are released from portal vein together with noradrenaline and dihydroxyphenylglycol during nerve stimulation. J Neurochem 59:972-82
Rorie, D K; Hunter, L W; Tyce, G M (1991) Neuropeptide Y and 3,4-dihydroxyphenylglycol effluxes from artery are oxygen sensitive. Am J Physiol 261:H1371-8
Kristensen, E W; Chinnow, S L; Montreuil, R S et al. (1990) Precursors and metabolites of norepinephrine in sympathetic ganglia of the dog. J Neurochem 54:1782-90
Rorie, D K; Hunter, L W; Lunn, J J (1990) Halothane decreases the release of neuropeptide Y and 3,4-dihydroxyphenylglycol from superfused segments of dog pulmonary artery. Anesthesiology 73:722-30
Lunn, J J; Murray, M J; Rorie, D K (1990) Endotoxin does not directly alter norepinephrine release or vasoactivity in dog pulmonary artery and portal vein. Crit Care Med 18:1408-12

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