ACh and ATP mediate excitatory transmission in cat carotid identified chemoreceptor units in vitro

Varas, R.; Alcayaga J.; Iturriaga R.

Abstract

Several molecules have been proposed as excitatory transmitters between glomus (type 1) cells and nerve terminals of petrosal ganglion (PG) neurons in the carotid body (CB). We tested whether ACh and ATP have a role to play as excitatory transmitters in the cat CB by recording intracellularly from identified PG neurons functionally connected to the CB in vitro. PG neurons projecting to the CB were classified according to their intracellular responses as: (a) neurons with humped action potentials (hAP neurons) responding phasically to long-lasting depolarizing pulses (53/67), and (b) neurons with smooth action potentials (non-hAP neurons) that fire tonically during long-lasting depolarizations (14/67). CB stimulation by stop flow and/or acidosis induced activity in 28 of 39 hAP-type neurons, being classified as chemosensory, but in none of the non-hAP neurons. Hexamethonium (10 ?M) and suramin (100 ?M) reversibly abolished the increased discharges evoked in chemosensory neurons (8/9) by stop flow or acidosis. Moreover, 24 of 27 chemosensory neurons responded to ganglionar application of ACh and ATP, while two neurons responded only to ACh and one to ATP. Mechanical deformation of the carotid sinus induced firing activity in 10 of 13 non-hAP neurons, but in none of the hAP neurons tested. Interestingly, 4/10 non-hAP neurons, which responded to carotid sinus mechanical stimulation also responded to ganglionar application of ATP, but were insensitive to ACh. Present results favor the hypothesis that ACh and ATP are excitatory transmitters in the cat CB, acting - at least - on the PG neuron terminals in the CB. © 2003 Elsevier B.V. All rights reserved.

Más información

Título según WOS: ACh and ATP mediate excitatory transmission in cat carotid identified chemoreceptor units in vitro
Título según SCOPUS: ACh and ATP mediate excitatory transmission in cat carotid identified chemoreceptor units in vitro
Título de la Revista: BRAIN RESEARCH
Volumen: 988
Número: 01-feb
Editorial: Elsevier
Fecha de publicación: 2003
Página de inicio: 154
Página final: 163
Idioma: English
URL: http://linkinghub.elsevier.com/retrieve/pii/S0006899303033663
DOI:

10.1016/S0006-8993(03)03366-3

Notas: ISI, SCOPUS