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Topography of preganglionic parasympathetic cardiac motor neurons labeled after underwater submersion.
Author(s) -
Panneton W. Michael,
Anch Michael A.,
Gan Qi
Publication year - 2007
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.21.6.a1360-b
Subject(s) - anatomy , medulla , rostral ventrolateral medulla , medulla oblongata , bradycardia , medicine , nucleus ambiguus , biology , heart rate , central nervous system , blood pressure
The mammalian diving response is marked by a robust bradycardia. Preganglionic parasympathetic cardiac motor neurons (PCMNs) are distributed in the ventrolateral medulla from the facial motor nucleus to the spinomedullary junction (see Panneton et al., Brain Res. 738 :, 1996). It has been suggested that chrono‐, dromo‐ and inotropic neurons are segregated in this column; we wished to find which neurons may be responsible for the negative chronotropism seen in diving. Rats were trained to dive underwater and then telemetric transmitters for monitoring arterial pressure implanted into their abdomens. After recovery, a thoracotomy was done and 8–20μl of 0.5–1.0% choleragenoid mixed with the vital dye fast green injected into their pericardial sacs. After 60–72 hrs, the rats dove underwater 3 times; bradycardia was dramatic with each dive, averaging near 80%. After 2 hrs, the rats were killed and their brains stained immunohistochemically for antibodies against choleragenoid and cFos. Labeled PCMNs were found throughout the ventrolateral medulla; very few were observed in the dorsal motor nucleus. Double labeled neurons also were found throughout the rostral‐caudal extent of the column of PCMNs, but more were found rostrally. Supported by NIH grant HL 64772.