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Modulation of respiratory rhythm by alpha 2-adrenoceptors in awake and anesthetized goats. J Appl Physiol (1985) 1994 Aug;77(2):742-50 PMID: 8002523

Pubmed ID

8002523

Abstract

The purpose of this study was to examine the effects of alpha 2-adrenoceptor agonists in the control of breathing with goats that were either awake (n = 7) or anesthetized and artificially ventilated (n = 11). Awake goats infused intravenously with either of the alpha 2-agonists clonidine (1.0-6.0 micrograms/kg) or guanabenz (15.0-63.0 micrograms/kg) exhibited two distinct ventilatory patterns. One pattern was characterized by tachypnea in which respiratory frequency and minute ventilation increased to approximately 50% above control values. A second ventilatory pattern consisted of slow breathing with reductions of respiratory frequency and minute ventilation and highly variable expiratory duration intervals. These two patterns were unaffected by bilateral carotid body denervation. In anesthetized goats, alpha 2-agonists also caused an arrhythmia in phrenic nerve activity that was similar to the slow breathing pattern seen in awake goats. Respiratory disturbances were abolished by the selective alpha 2-receptor antagonist SKF-86466 (100-500 micrograms/kg), indicating that the effects are mediated by alpha 2-receptors. The results suggest that stimulation of alpha 2-adrenoceptors generally has an inhibitory effect on breathing in goats. The disruption of ventilation with clonidine or guanabenz suggests that alpha 2-adrenoceptors may play an important role in the control of central respiratory rhythm.

Author List

Hedrick MS, Ryan ML, Pizarro J, Bisgard GE

Author

Melinda R. Dwinell PhD Center Associate Director, Associate Professor in the Physiology department at Medical College of Wisconsin




Scopus

2-s2.0-0027981310   27 Citations

MESH terms used to index this publication - Major topics in bold

Adrenergic alpha-2 Receptor Agonists
Adrenergic alpha-Antagonists
Anesthesia
Animals
Benzazepines
Blood Gas Analysis
Blood Pressure
Carotid Body
Clonidine
Goats
Guanabenz
Heart Rate
Hypercapnia
Phrenic Nerve
Respiration, Artificial
Respiratory Mechanics
Vagotomy
jenkins-FCD Prod-300 626508253d14e4184314fb9f66322a03a5906796