title: Differential effects of cardiac sympathetic afferent stimulation on neurons in the nucleus tractus solitarius.
abstract: Activation of the cardiac "sympathetic afferent" reflex (CSAR) has been reported to depress the arterial baroreflex and enhance the arterial chemoreflex via a central mechanism. In the present study, we used single-unit extracellular recording techniques to examine the effects of stimulation of cardiac sympathetic afferents on baro- or chemosensitive neurons in the nucleus tractus solitarius (NTS) in anesthetized rats. Of 54 barosensitive NTS neurons tested for their response to epicardial application of capsaicin (0.4 microg), 38 were significantly (P<0.01) inhibited by 38% while 16 did not respond. Of 42 NTS chemosensitive neurons tested for their response to capsaicin, 33 were significantly (P<0.01) excited by 47% while 9 did not respond. In addition, of 12 both barosensitive and chemosensitive NTS neurons tested for capsaicin, 2 were excited, 7 were inhibited, and 3 did not respond. In conclusion, this study indicates that CSAR activation inhibited NTS barosensitive neurons and excited NTS chemosensitive neurons, suggesting that the NTS plays an important role in processing the interactions between these cardiovascular reflexes.
authors.affiliation: Department of Cellular and Integrative Physiology, University of Nebraska Medical Center, Omaha, NE 68198-5850, USA.
authors.forename: Wei-Zhong
authors.initials: WZ
authors.lastname: Wang
authors.forename: Lie
authors.initials: L
authors.lastname: Gao
authors.forename: Yan-Xia
authors.initials: YX
authors.lastname: Pan
authors.forename: Irving H
authors.initials: IH
authors.lastname: Zucker
authors.forename: Wei
authors.initials: W
authors.lastname: Wang
mesh_terms: D000818:Animals; D001794:Blood Pressure / Q000187:drug effects / Q000502:physiology; D002211:Capsaicin / Q000494:pharmacology; D002628:Chemoreceptor Cells / Q000187:drug effects / Q000502:physiology; D004558:Electric Stimulation; D006321:Heart / Q000187:drug effects / Q000294:innervation* / Q000502:physiology*; D006339:Heart Rate / Q000187:drug effects / Q000502:physiology; D008297:Male; D009474:Neurons / Q000187:drug effects / Q000502:physiology*; D011311:Pressoreceptors / Q000187:drug effects / Q000502:physiology; D051381:Rats; D017207:Rats, Sprague-Dawley; D012018:Reflex / Q000502:physiology; D017552:Solitary Nucleus / Q000166:cytology / Q000187:drug effects / Q000502:physiology*; D013268:Stimulation, Chemical; D013564:Sympathetic Nervous System / Q000166:cytology / Q000187:drug effects / Q000502:physiology*
chemical_list: D002211:Capsaicin