Glomus cells

Non-neuronal transplants such as adrenal chromaffin cells have been tried but do not survive although some L-dopa-producing cell lines (e.g. PC 12) or glomus cells of the carotid body do produce DA in vivo and may provide the equivalent of a continuous infusion of dopa (and DA) directly into the brain. Expression of tyrosine hydroxylase to promote dopa and DA synthesis in striatal cells by direct gene transfer in vivo or in cultures for subsequent transplanting, may also be possible. (See Dunnett and Bjorklund 1999 for a review of these approaches.)... 

Neuronal nicotinic receptors are present on sensory nerve endings—especially afferent nerves in coronary arteries and the carotid and aortic bodies as well as on the glomus cells of the latter. Activation of these receptors by nicotinic stimulants and of muscarinic receptors on glomus cells by muscarinic stimulants elicits complex medullary responses, including respiratory alterations and vagal discharge. 

A Representative Conserved Control System The Glomus Cell -> Vagal Control of the Heart... 

Carotid body glomus cell (Signal transduction pathways) -----------7-------- -----------... 

Lopez-Barneo J. 2003. Oxygen and glucose sensing by carotid body glomus cells. Curr Opin Neurobiol 13 493-499. 

Oligomycim and Antimycin A Abolished the Calcium Response of the Glomus Cells but... 

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... 

Glomus cell responses (a) Oligomycin abolished the calcium response to hypoxia (Hx), but exaggerated the same to hypercapnia, (b) 2-APB (IP3 antagonist) drastically reduced (From Lahiri, 2004)... 

A decrease below the threshold Pq, normally close to 50 Torr, in glomus cells of the carotid body or in the neonatal ductus arteriosus results in an inhibition of the tonic K current. Such oxygen-regulated inhibition of K+ channels, which may be mediated by mitochondria-derived hydrogen peroxide (Archer et al., 2004), results in an increase in cellular excitability, increased Ca + influx, and a resultant increase in the level of Ca + in the cytosol (reviewed by Lopez-Barneo et al., 1999). 

Excitable Cells Carotid Body Glomus Cell as a Primary Example... 

A schematic representation of how a decrease in oxygen tension (hypoxia) may affect carotid body glomus cell function. In the mitochondrial model, hypoxia affects either reactive oxygen species (ROS) production or ATP production of mitochondria. Both of these may affect the outward flux of potassium via the potassium channel with the downstream effects shown in the diagram. In the membrane model, the ROS production by membrane-bound molecules (cytochromes) is oxygen sensitive, and thereby affected by hypoxia. Thus, these membrane-bound molecules function as proximal oxygen sensors and cause effects on potassium channels with the downstream effects described in the figure and in the text... 

Roy A, Rozanov C, Mokashi A, Daudu P, Al-mehdi AB, et al. 2000. Mice lacking in gp91 phox subunit of NAD(P)H oxidase showed glomus cell [Ca ] and respiratory responses to hypoxia. Brain Res 872 188-193. 

Summers BA, Overholt JL, Prabhakar NR. 2000. Augmentation of calcium current by hypoxia in carotid body glomus cells. Adv Exp Med Biol 475 589-599. 

Verna, A., Rowny, M., and Leitner, L.M., Loss of chemoreceptor properties of the rabbit carotid body after destruction of the glomus cells. Brain Res., 100, 13-23, 1975. 

Glomovenous malformations are venous malformations associated with glomus cells. The smooth layer is formed hy glomus cells, which are smooth muscle precursor cells [11]. Glomovenous malformations frequently recur. Sclerotherapy can he useful for their treatment. 

Hypoxia in the CB may (1) inhibit K" " current producing depolarization of the chemosensitive cells (glomus cells), (2) lead to the opening of voltage-gated Ca " "... 

Around birth the CB increase in size. In the cat, between the late fetal and the early postnatal period, the CB volume increases by over 50% in vascular and nonvascular compartments (61). In the rat, glomus cells occasionally have been reported to undergo mitosis during the late fetal and early postnatal period (62,63). The number of nerve terminals increases about fourfold during the neonatal period (64). These morphological changes could participate in the functional and neurochemical maturation of this tissue. 

Fishman MC, Schaffner AE. Carotid body cell culture and selective growth of glomus cells. Am J Physiol 1984 246 C106-C113. 

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