Two types of rhythm in the respiratory network output in the isolated ventrolateral medulla in the neonatal rats.
Effects of substance P and extracellular [K(+)](o) on respiratory motor activity in the ventrolateral medulla in neonatal rat (0-4 days old) brainstem-spinal cord preparation were studied. In addition to fictive eupneic rhythm (8-13 bursts/minute), the respiratory motor output was composed of biphasic bursts which might underlie the sigh pattern in vivo. These bursts had considerably lower frequency (0.15-0.86 bursts/minute) and appeared when inspiratory neurons generated augmented biphasic discharges. The two rhythms were differently affected when the respiratory network excitability was increased by substance P or decreased by lowering external [K(+)](o), the effects on biphasic burst frequency being considerably greater. The augmented bursts could suppress inspiratory, but not pre-inspiratory neuron discharge, suggesting that pre-inspiratory neurons formed a supplementary rhythmic network which was not directly affected by biphasic burst generation.
Shvarev
Y N
YN
Department of Woman and Child Health, Q2: 07, Neonatal Research Unit, Astrid Lindgren Children's Hospital, Karolinska Institutet, SE-171 76, Stockholm, Sweden. yuri.shvarev@kbh.ki.se
Lagercrantz
H
H
Yamamoto
Y
Y
D000818:Animals; D000831:Animals, Newborn; D066298:In Vitro Techniques; D008526:Medulla Oblongata / Q000166:cytology / Q000187:drug effects / Q000502:physiology*; D009415:Nerve Net / Q000166:cytology / Q000187:drug effects / Q000502:physiology*; D009474:Neurons / Q000187:drug effects / Q000502:physiology; D018408:Patch-Clamp Techniques; D010507:Periodicity; D011188:Potassium / Q000378:metabolism; D051381:Rats; D017208:Rats, Wistar; D012125:Respiratory Center / Q000166:cytology / Q000187:drug effects / Q000502:physiology*; D015656:Respiratory Mechanics; D013373:Substance P / Q000494:pharmacology / Q000502:physiology
D013373:Substance P; D011188:Potassium