title: Regulation of respiratory-related hypoglossal motor output by α₁ adrenergic and serotonin 5-HT₃ receptor activation in isolated adult turtle brainstems.
abstract: The effects of brainstem α(1) adrenergic receptor activation on respiratory control in reptiles are poorly understood. Isolated adult turtle brainstems were exposed to phenylephrine (α(1) adrenergic agonist) and respiratory motor bursts were recorded on hypoglossal nerves. Phenylephrine acutely increased burst frequency, amplitude (low concentrations only), and regularity of the time interval between the start of respiratory events (single or clustered bursts), and decreased bursts/respiratory event. Burst frequency and timing changes persisted during a 2.0 h washout. Acute increases in burst frequency and amplitude were blocked by prazosin (α(1) adrenergic antagonist). Pretreatment with prazosin and tropisetron (5-HT(3) antagonist) blocked the increase in respiratory event regularity, but did not alter the decrease in bursts/respiratory event. Intermittent phenylephrine application (4 × 5.0 min separated by 20 min) did not produce long-lasting changes in burst frequency and amplitude, bursts/respiratory event, or respiratory event regularity. Thus, sustained α(1) adrenergic receptor activation in turtle brainstems produces acute and long-lasting changes in respiratory burst frequency and pattern.
authors.affiliation: Department of Comparative Biosciences, School of Veterinary Medicine, University of Wisconsin, Madison, WI 53706, USA.
authors.forename: Michelle E
authors.initials: ME
authors.lastname: Bartman
authors.forename: Stephen M
authors.initials: SM
authors.lastname: Johnson
mesh_terms: D058646:Adrenergic alpha-1 Receptor Agonists / Q000494:pharmacology; D058668:Adrenergic alpha-1 Receptor Antagonists / Q000494:pharmacology; D000818:Animals; D001933:Brain Stem / Q000187:drug effects / Q000502:physiology*; D055724:Electrophysiological Phenomena / Q000187:drug effects; D007002:Hypoglossal Nerve / Q000187:drug effects / Q000502:physiology*; D007211:Indoles / Q000494:pharmacology; D010656:Phenylephrine / Q000494:pharmacology; D011224:Prazosin / Q000494:pharmacology; D012119:Respiration / Q000187:drug effects; D012137:Respiratory System / Q000187:drug effects / Q000294:innervation*; D012702:Serotonin Antagonists / Q000494:pharmacology; D000077526:Tropisetron; D014426:Turtles / Q000502:physiology*
chemical_list: D058646:Adrenergic alpha-1 Receptor Agonists; D058668:Adrenergic alpha-1 Receptor Antagonists; D007211:Indoles; D012702:Serotonin Antagonists; D010656:Phenylephrine; D000077526:Tropisetron; D011224:Prazosin