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Titolo:
Role of glutamate receptors in transmission of vagal cardiac input to neurones in the nucleus tractus solitarii in dogs
Autore:
Seagard, JL; Dean, C; Hopp, FA;
Indirizzi:
Med Coll Wisconsin, Zablocki Vet Adm Med Ctr, Milwaukee, WI 53295 USA Med Coll Wisconsin Milwaukee WI USA 53295 ed Ctr, Milwaukee, WI 53295 USA Med Coll Wisconsin, Dept Anesthesiol, Milwaukee, WI 53295 USA Med Coll Wisconsin Milwaukee WI USA 53295 hesiol, Milwaukee, WI 53295 USA
Titolo Testata:
JOURNAL OF PHYSIOLOGY-LONDON
fascicolo: 1, volume: 520, anno: 1999,
pagine: 243 - 253
SICI:
0022-3751(19991001)520:1<243:ROGRIT>2.0.ZU;2-F
Fonte:
ISI
Lingua:
ENG
Soggetto:
AMINO-ACID RECEPTORS; CAROTID-SINUS BARORECEPTORS; IN-VIVO MICRODIALYSIS; NON-NMDA RECEPTORS; ELECTRICAL-STIMULATION; CONVERGENCE PROPERTIES; SYNAPTIC TRANSMISSION; VAGUS NERVE; RAT VAGAL; CAT;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Life Sciences
Citazioni:
40
Recensione:
Indirizzi per estratti:
Indirizzo: Seagard, JL Med Coll Wisconsin, Zablocki Vet Adm Med Ctr, 5000 W Natl Ave,Milwaukee, WI 53295 USA Med Coll Wisconsin 5000 W Natl Ave Milwaukee WI USA 53295 USA
Citazione:
J.L. Seagard et al., "Role of glutamate receptors in transmission of vagal cardiac input to neurones in the nucleus tractus solitarii in dogs", J PHYSL LON, 520(1), 1999, pp. 243-253

Abstract

1.. Vagal afferent input from cardiac mechanoreceptors excites neurones inthe nucleus tractus solitarii (NTS), but discharge patterns evoked by physiological activation of pressure-sensitive cardiac mechanoreceptors have not been studied in, vivo. The role of glutamate receptor subtypes in transmission of afferent activity to the NTS neurones has not been determined. Thepresent study therefore has two aims: first, to characterise the dischargepatterns of neurones in the NTS that receive pressure-sensitive vagal cardiac receptor input and second, to determine the roles of ionotropic glutamate receptor subtypes in the transmission of this putative cardiac mechanoreceptor-related activity to NTS neurones.2. Pulse-synchronous activity of neurones in the NTS evoked by vagal afferent input was recorded extracellularly in an anaesthetised dog model using multibarrel glass electrodes, which allowed picoejection of the glutamate receptor antagonists NBQX or AP5 to block either non-NMDA or NMDA receptors,respectively, during the neuronal recording. Pressure sensitivity of the recorded neurones was examined by monitoring their response to a small increase in arterial blood pressure. Selective pressure activation of carotid sinus baroreceptors in an isolated sinus or selective denervation of aortic baroreceptors were used to test for convergent excitation of the neurones byarterial baroreceptors.3. Pulse-synchronous cardiac-related neuronal activity recorded from neurones in both the Fight and left NTS was eliminated following section of the left (n = 17) or right (n = 1) vagus nerves. No spontaneous, non-pulsatile activity was observed in these neurones before or after vagotomy. Activity transmitted via left vagal afferents was found to be sensitive to changes in arterial blood pressure. In these neurones, activity was blocked in 13 of17 neurones by picoejection of NBQX, with the remainder requiring both NBQX and AP5. None of the cardiac-related neurones responded to activation of carotid baroreceptors or denervation of aortic baroreceptors, indicating noconvergence of activity from carotid baroreceptors or aortic baroreceptorswith pressure thresholds of approximately 130 mmHg or less.4. The results suggest that vagal pressure-sensitive afferent input from cardiac mechanoreceptors is transmitted primarily by left vagal afferent fibres via non-NMDA receptors to neurones in both the ipsilateral and contralateral NTS. NMDA receptors were also found to have a role in the activation of a small subpopulation of neurones.

ASDD Area Sistemi Dipartimentali e Documentali, Università di Bologna, Catalogo delle riviste ed altri periodici
Documento generato il 09/07/20 alle ore 14:22:34