Cardiac vagal preganglionic neurones in the intermediate zone of the brainstem in anaesthetized cats.
Cardiac vagal preganglionic neurones (CVPNs) show respiratory modulation in the nucleus ambiguus but not in the dorsal vagal nucleus. Both types of neurones can be activated by pulmonary C fibre afferents. Another brainstem area that has been identified as containing CVPNs is the intermediate zone between the dorsal vagal nucleus and nucleus ambiguus. Experiments were carried out in alpha-chloralose-anaesthetized cats to determine the physiological properties of these CVPNs and their responses to pulmonary C fibre afferent activation. Seven CVPN axons in the right cardiac vagal branches were identified and found to be localized in the intermediate zone with a conduction velocity of between 1.2 and 1.6 m s(-1), in the C fibre range. These seven CVPNs [either showing spontaneous activity (n = 1) or having activity induced by dl-homocysteic acid applied ionophoretically (n = 3)] were neither respiratory modulated nor did they receive a baroreceptor input, thus being similar to those found in the dorsal vagal nucleus. Right atrial injections of phenylbiguanide excited all four CVPNs tested. In conclusion, CVPNs located in the intermediate zone have similar properties to those in the dorsal vagal nucleus but not the nucleus ambiguus.
Kong
Shuzhen
S
Research Centre of Medicinal Chemistry and Chemical Biology, Chongqing Technology and Business University, Chongqing, China.
Liu
Jian-Hui
JH
Ramage
Andrew G
AG
Wang
Yun
Y
D000200:Action Potentials / Q000187:drug effects / Q000502:physiology; D018686:Anesthetics, Intravenous; D000818:Animals; D001339:Autonomic Fibers, Preganglionic / Q000502:physiology; D001645:Biguanides / Q000494:pharmacology; D002415:Cats; D002698:Chloralose; D005260:Female; D006321:Heart / Q000294:innervation* / Q000502:physiology; D006329:Heart Conduction System / Q000166:cytology* / Q000502:physiology; D008297:Male; D008526:Medulla Oblongata / Q000166:cytology* / Q000502:physiology; D036421:Nerve Fibers, Unmyelinated / Q000187:drug effects / Q000502:physiology; D012143:Respiratory Physiological Phenomena; D017366:Serotonin Receptor Agonists / Q000494:pharmacology; D014630:Vagus Nerve / Q000166:cytology* / Q000187:drug effects / Q000502:physiology
D018686:Anesthetics, Intravenous; D001645:Biguanides; D017366:Serotonin Receptor Agonists; D002698:Chloralose; C008846:phenyl biguanide