Existence of an Alpha One-Adrenoceptor-Mediated Coronary Vasoconstrictor Reflex During Acute Systemic Hypoxia, in Anesthetized, Open-Chest Dogs
The presence of an alpha-adrenoceptor--mediated coronary vasoconstrictor reflex during acute systemic hypoxia was examined in thirteen chloralose-anesthetized dogs. Local vasodilator effects were avoided by perfusing the left common coronary artery (LCC) with normoxic blood, while the dogs were vent...
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| Format: | Others |
| Language: | English |
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North Texas State University
1987
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| Online Access: | https://digital.library.unt.edu/ark:/67531/metadc501191/ |
| Summary: | The presence of an alpha-adrenoceptor--mediated coronary vasoconstrictor reflex during acute systemic hypoxia was examined in thirteen chloralose-anesthetized dogs. Local vasodilator effects were avoided by perfusing the left common coronary artery (LCC) with normoxic blood, while the dogs were ventilated with 5% 02-95% N2 . Left ventricular afterload was held constant and positive cardiac inotropic responses and beta two-adrenoceptor-mediated coronary vasodilation were blocked by propranolol. Parasympatheticmediated bradycardia and coronary vasodilation were blocked with atropine. Systemic hypoxia decreased LCC flow to normoxic myocardium by 19.4+2.6 %. Although myocardial oxygen extraction increased 9.7+2.9 %, myocardial oxygen consumption decreased 16.5+2.6 %. Intracoronary prazosin prevented the reflex vasoconstriction during repeated hypoxia. |
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