Regulation of respiratory-related hypoglossal motor output by α1 adrenergic and serotonin 5-HT3 receptor activation in isolated adult turtle brainstems

Department of Comparative Biosciences, School of Veterinary Medicine, University of Wisconsin, Madison, WI 53706, USA.
Respiratory Physiology & Neurobiology (Impact Factor: 1.97). 03/2012; 181(2):202-13. DOI: 10.1016/j.resp.2012.03.004
Source: PubMed

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.

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