Petrosal ganglion

The only other group of neurons responsive exclusively to salts was the rat PG salt unit group (Fig. 3). These units of the petrosal ganglion responded to a variety of Cl salts, not showing the Na,... 

Geniculate Ganglion (Facial Nerve) GG. Petrosal Ganglion (Glossopharyngeal Nerve) PG... 

Present in the rat petrosal ganglion was another set of acid units responsive primarily to certain carboxylic acids. Unlike the cat (7), the rat was unresponsive to some carboxylic acids even though they were in low pH solutions (2). Possibly the same is true for the rat GG acid units which were not investigated in as much detail. PG acid units, unlike all other acid unit groups, responded in a "grouping" discharge fashion. 

List of Abbreviations CA, carbonic anhydrase Hx, hypoxia IbTX, iberiotoxin PGN, Petrosal ganglion neurons RTN, retrotrapezoid VLM, ventrolateral medullary area... 

Using the same coculture techniques, glomus cells with petrosal ganglion cells (PGN) and recording from the PGN neurons, it was shown that PGN cells and their terminals responded to hypoxia and CO2/PH and not the PGN cells alone (Zhong et al., 1997 Prasad et al., 2001 Zhang and Nurse, 2004). This means that neurotransmitters released from the glomus cells excited the PGN cells. These transmitters consisted of ATP and ACh. Similar results were obtained by Varas et al. (2003). Recorded intracellularly from identified PGN functionally connected with the carotid body (CB) in vitro, and which responded to CB stimulation by stop... 

More recently, successful reinnervation of carotid body glomus cells, changes in the electrical properties, pharmacological sensitivity, and reappearance of hypoxic chemosensitivity in petrosal ganglion cells have been reported when explants of both organs are cultured together (31-35). Petrosal ganghon neurons acutely disconnected from the carotid body and superfused in vitro are not excited by hypoxic hypoxia (36). 

Alcayaga J, Arroyo J. Responses of cat petrosal ganglion neurons are modified by the presence of carotid body cells in tissue cultures. Adv Exp Med Biol 1996 410 195-201. Zhong H, Zhang M, Nurse C. Synapse formation and hypoxic signaling in co-cultures of rat petrosal neurones and carotid body type 1 cells. J Physiol (Lond) 1997 503 ... 

Ishizawa Y, Fitzgerald RS, Shirahata M, Schofield B. Localization of nicotinic acetylcholine receptors in cat carotid body and petrosal ganglion. Adv Exp Med Biol 1996 410 253-256. 

Figure 1 Model of cat carotid body s components thought to he involved in carotid body chemotransduction. NTS nucleus tractus solitarii in the hrainstem PG petrosal ganglion Al, A2a adenosine receptors P2X2 purinoceptor Ml, M2 types of muscarinic receptors N nicotinic receptors Dl, D2 dopamine receptors K potassium channels VGCC voltagegated calcium channels Ach acetylcholine DA dopamine NE norepinephrine SP substance P ATP adenosine triphosphate NO nitric oxide. The glomus cell, embraced by the calyx type sensory afferent fiber, contains several putative neurotransmitters. It is highly unlikely that every glomus cell contains all the listed neurotransmitters. Presumably the neurotransmitter can act wherever the appropriate receptors are located, postsynaptically as well as presynaptically. See text for postulated steps in the release of the neurotransmitters.

II. Nitric Oxide Synthase Localization in the Carotid Body and Petrosal Ganglion... 

Alcayaga J, Iturriaga R, Varas R, Arroyo J, Zapata P. Selective activation of carotid nerve fibers by acetylcholine applied to the cat petrosal ganglion in vitro. Brain Res 1998 786 47-54. 

Alcayaga J, Barrios M, Bustos F, Miranda G, Molina y Iturriaga R. Modulatory effect of nitric oxide on acetylchohne-induced activation of cat petrosal ganglion neurons in vitro. Brain Res 1999 825 194-198. 

Petrosal ganglion Nodose ganglion Carotid body ... 

Figure 8 Integrated antidromic neural activity in the carotid sinus nerve (CSN) and lingual nerve (LN) branches of the glossopharyngeal nerve (IXth n.). Nerve preparation was superfused in vitro. Superimposed traces show that application of a 100-pg bolus (arrows) of ACh to the petrosal ganglion evokes a substantial increase in the CSN and LN nerve discharge, which is inhibited in the presence of 100 pM mecamylamine, a nicotinic receptor antagonist.

Chen J, He L, Dinger B, Stensaas L, Fidone S. Chronic hypoxia upregulates connexin43 expression in rat carotid body and petrosal ganglion. J Appl Physiol 2002. In press. 

Figure 1 Intracellularly recorded action potentials, evoked by brief pulses, from cat petrosal ganglion neurons in tissue culture, (a) A neuron that responds with a brief action potential with a smooth repolarizing phase, (b) A neuron responding with an action potential presenting a clear hump, or inflection, in the repolarizing phase.

Figure 2 ACh-induced responses in the cat petrosal ganglion and in isolated neurons in culture, (a) Increases in the carotid sinus nerve frequency discharge ( csn) evoked by the application of increasing AQi doses (2-500 pg) to the ganglion (arrowhead), (b) Dose-response relationship for the significant increases in csn (Afew) observed in (a), (c) Depolarization and firing of multiple action potentials, recorded with intracellular microelectrode, elicited by application of an ACh (200 pM) bolus (arrowhead), (d) Inwardly directed inactivating current, recorded in whole-cell voltage-clamp configuration at Vm = —60 my induced by a 4-sec ACb (500 pM) pulse (continuous line).

Figure 3 ATP-induced responses in the cat petrosal ganglion and in isolated neurons in...

Alcayaga J, Arroyo J, Font MI, Gutierrez O. The petrosal ganglion of the adult cat neuronal count, sectional area, and their respective distributions. Biol Res 1996 29 189-... 

Morales A, Ivorra I, Gallego R. Membrane properties of glossopharyngeal sensory neurons in the petrosal ganglion of the cat. Brain Res 1987 401 340-346. 

Alcayaga J, Arroyo J. Responses of cat petrosal ganglion neurons are modified by the presence of carotid body cells in tissue cultures. Adv Exp Med Biol 1996 410 195-201. 

Andrews EM, Kunze DL. Voltage-gated K+ channels in chemoreceptor sensory neurons of rat petrosal ganglion. Brain Res 2001 897 199-203. 

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