Serotonin 1A-receptor activation suppresses respiratory apneusis in the cat.
Malfunction of inhibitory synaptic processes in the brainstem result in abnormal prolonged inspiration (apneusis). Since we previously found that the serotonin (5-hydroxytryptamine; 5-HT) 5-HT1A receptor agonist 8-hydroxy-dipropylaminotetralin (8-OH-DPAT) shortens inspiratory discharges, we tested its ability to suppress apneusis. We recorded phrenic nerve activity and the membrane potential of medullary expiratory (E-2) and postinspiratory (PI) neurons in 14 anaesthetized, paralyzed, artificially ventilated cats. Systemic hypoxia or i.v. injection of pentobarbital sodium or the N-methyl-D-aspartate (NMDA) receptor blocker ketamine induced apneustic phrenic nerve discharges, delayed depolarization to threshold of E-2 neurons and prolonged hyperpolarization in PI neurons. 8-OH-DPAT (10-40 micrograms/kg i.v.) produced partial to complete restoration of normal phrenic nerve discharges and membrane potential.
Lalley
P M
PM
II. Institute of Physiology, University of Goettingen, FRG.
Bischoff
A M
AM
Richter
D W
DW
D017371:8-Hydroxy-2-(di-n-propylamino)tetralin / Q000008:administration & dosage / Q000494:pharmacology*; D000818:Animals; D002415:Cats; D005260:Female; D000860:Hypoxia / Q000503:physiopathology; D007276:Injections, Intraventricular; D007649:Ketamine / Q000037:antagonists & inhibitors / Q000494:pharmacology; D008297:Male; D008564:Membrane Potentials / Q000187:drug effects; D010424:Pentobarbital / Q000037:antagonists & inhibitors / Q000494:pharmacology; D010791:Phrenic Nerve / Q000187:drug effects / Q000503:physiopathology; D011985:Receptors, Serotonin / Q000187:drug effects / Q000378:metabolism*; D015656:Respiratory Mechanics / Q000187:drug effects*; D013569:Synapses / Q000187:drug effects
D011985:Receptors, Serotonin; D007649:Ketamine; D017371:8-Hydroxy-2-(di-n-propylamino)tetralin; D010424:Pentobarbital