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Cardiac vagal preganglionic neurones in the intermediate zone of the brainstem in anaesthetized cats
Author(s) -
Kong Shuzhen,
Liu JianHui,
Ramage Andrew G.,
Wang Yun
Publication year - 2007
Publication title -
experimental physiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.925
H-Index - 101
eISSN - 1469-445X
pISSN - 0958-0670
DOI - 10.1113/expphysiol.2007.039230
Subject(s) - nucleus ambiguus , chloralose , brainstem , nucleus , medulla oblongata , dorsal motor nucleus , chemistry , vagus nerve , anatomy , baroreceptor , cats , biology , medicine , neuroscience , heart rate , central nervous system , blood pressure , stimulation
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 α‐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.