Effects of chronic hypoxia on opioid peptide and catecholamine levels and on the release of dopamine in the rabbit carotid body.
Carotid body catecholamine and opioid levels were measured in rabbits exposed for 8 days to an atmosphere of 11% O2 in N2 (PO2 of approximately 80 mm Hg) and during an identical period of recovery, i.e., after 8 days of returning to the control normoxic atmosphere. Carotid bodies show a decrease in dopamine content at day 2. Thereafter, the levels of this biogenic amine increase progressively to peak at day 10, that is, 2 days after returning to a normoxic atmosphere. Finally, dopamine levels start to decrease and reach prehypoxic control levels at day 16, that is, after 8 days of recovery. In contrast, levels of native opioid peptides remain unchanged during the whole duration of the experiment, except for a decrease at day 2 of the hypoxic exposure. Levels of total opioid peptides are also below control values at day 2 of hypoxia, increase above control values on returning to a normoxic atmosphere (maximal levels at days 10-12), and later decrease to reach prehypoxic levels at day 16. As a result of these changes the ratios of dopamine to opioid levels show a progressive increase from day 0 to day 10 of the experiment and then return to control prehypoxic values. Carotid bodies isolated from animals that have been exposed to hypoxia for 8 days synthesize [3H]dopamine from its natural precursor [3H]tyrosine at a rate of 175 pmol/mg of protein/h, which is about double the rate of synthesis found in the carotid bodies of control animals and those allowed to recover for 8 days.(ABSTRACT TRUNCATED AT 250 WORDS)
González-Guerrero
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Departamento de Bioquímica y Biología Molecular y Fisiologia, Facultad de Medicina, Universidad de Valladolid, Spain.
Rigual
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González
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D000818:Animals; D002344:Carotid Body / Q000378:metabolism*; D002395:Catecholamines / Q000378:metabolism*; D002908:Chronic Disease; D004298:Dopamine / Q000378:metabolism*; D004723:Endorphins / Q000378:metabolism*; D000860:Hypoxia / Q000378:metabolism*; D010100:Oxygen / Q000494:pharmacology; D011817:Rabbits; D012016:Reference Values
D002395:Catecholamines; D004723:Endorphins; D010100:Oxygen; D004298:Dopamine