Hemodynamic interaction of chloralose pretreatment with subsequent beta-adrenergic receptor antagonism in lambs

• Published in: Biology of the neonate Vol. 66; no. 6; p. 316
• Main Authors: Covert, R F, Drummond, W H
• Format: Journal Article
• Language: English
• Published: Switzerland 1994
• Subjects: Adrenergic beta-Antagonists - pharmacology; Animals; Animals, Newborn - physiology; Blood Gas Analysis; Blood Pressure - drug effects; Blood Pressure - physiology; Cardiac Output - drug effects; Cardiac Output - physiology; Cardiovascular Physiological Phenomena; Cardiovascular System - drug effects; Chloralose - pharmacology; Drug Interactions; Female; Heart Rate - drug effects; Heart Rate - physiology; Hemodynamics - drug effects; Hemodynamics - physiology; Isoproterenol - pharmacology; Male; Propranolol - pharmacology; Receptors, Adrenergic, beta - drug effects; Receptors, Adrenergic, beta - physiology; Sheep - physiology; Vascular Resistance - drug effects; Vascular Resistance - physiology
• ISSN: 0006-3126
• DOI: 10.1159/000244124

alpha-Chloralose is a commonly used anesthetic agent in cardiovascular research despite a paucity of information whether it may have important pharmacologic interaction with subsequently given adrenergic drugs. To assess any potential pharmacologic interaction, we studied the cardiovascular response to beta-adrenergic receptor antagonism (propranolol, 1 mg/kg i.v.) after either chloralose (30 mg/kg i.v.) or saline control in paired studies in 10 chronically instrumented neonatal lambs. Chloralose increased heart rate by 46% as compared to control (283 +/- 37 vs. 194 +/- 48 beats/min, p = 0.0002) and had no significant effect on cardiac output; chloralose also increased mean pulmonary arterial pressure by 45% (27 +/- 13 vs. 19 +/- 6 mm Hg, p = 0.050) and pulmonary vascular resistance by 79% (0.211 +/- 0.13 vs. 0.118 +/- 0.04 mm Hg/ml/kg/min, p = 0.050). The group pretreated with chloralose had significantly elevated heart rate (186 +/- 23 vs. 157 +/- 31 beats/min, p = 0.03), mean pulmonary arterial pressure (29 +/- 9 vs. 22 +/- 6 mm Hg, p = 0.03) and pulmonary vascular resistance (0.228 +/- 0.13 vs. 0.130 +/- 0.05 mm Hg/ml/kg/min, p = 0.05) after propranolol as compared to the conscious saline-treated group. We conclude that pretreatment with chloralose as an anesthetic agent may produce important pharmacologic interaction with subsequent adrenergic drugs in neonatal lambs. While anesthesia may be necessary in animal research, investigators should be aware that the anesthetic agent may also qualitatively and quantitatively influence measured outcome variables.