Control of negative inotropic vagal preganglionic neurons in the dog: synaptic interactions with substance P afferent terminals in the nucleus ambiguus?

Autor: Blinder KJ; Department of Pharmacology, Howard University College of Medicine, 50 W Street, NW, Washington, DC 20059, USA., Dickerson LW, Gray AL, Lauenstein JM, Newsome JT, Bingaman MT, Gatti PJ, Gillis RA, Massari VJ
Jazyk: angličtina
Zdroj: Brain research [Brain Res] 1998 Nov 09; Vol. 810 (1-2), pp. 251-6.
DOI: 10.1016/s0006-8993(98)00877-4
Abstrakt: Previous research from this laboratory has shown that substance P-immunoreactive (SP) terminals synapse upon negative chronotropic vagal preganglionic neurons (VPNs), but not upon negative dromotropic VPNs, of the ventrolateral nucleus ambiguus (NA-VL). Moreover, SP agonists injected into NA-VL cause bradycardia without decreasing AV conduction. In the current study, we have: (1) defined the electron microscopic characteristics of the SP neurons of NA-VL in dog; and (2) tested the hypothesis that SP nerve terminals synapse upon negative inotropic VPNs of NA-VL, retrogradely labeled from the cranial medial ventricular (CMV) ganglion. Numerous SP terminals and a few SP neurons were observed in the vicinity of retrogradely labeled neurons. SP terminals were observed forming synapses with unlabeled dendrites and with SP dendrites, but never with the retrogradely labeled neurons. Together, these results and earlier findings suggest that SP agonists may be able to induce bradycardia without decreasing AV conduction or ventricular contractility.
(Copyright 1998 Elsevier Science B.V.)
Databáze: MEDLINE
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