Effects of Efferent Neurotransmitters on Intracellular Ca<sup>2+</sup>Concentration in Vestibular Hair Cells of the Guinea Pig

Yamashita, Toshio; Ohnishi, Shiho; Ohtani, Makiko; Kumazawa, Tadami

doi:10.3109/00016489309126173

Cited by 20 publications

(9 citation statements)

References 21 publications

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“…These findings may indicate that isolated ES epithelial cells preserve their cellular activity both morphologically and physiologically. Similar findings were also observed in chick isolated hair cells [11], in guinea pig outer hair cells [12] and in guinea pig vestibular sensory cells [7]. The ATP-activated channels provide a pathway for Ca 2+ entry with biophysical and pharmacological properties quite different from the voltage-gated L-or T-type Ca 2+ channel [13].…”

Section: Discussionsupporting

confidence: 69%

“…), which records fura-2 fluorescence using an ultrasensitive camera and measures the Ca 2+ concentration by means of a real-time digital image processor. A calcium concentration image (fluorescence ratio) is presented by mathematical processing (division of the images and background cut) of fluorescence images, under two excitation lights [7,8].…”

Section: Isolation Of Es Epithelial Cellsmentioning

confidence: 99%

“…The light was focused on a low-light, silicon-intensified target camera with its material fed into the computer system, ARGUS 100/CA. 340/380 fluorescence intensity ratio was used to assess the intracellular Ca 2+ concentration [7,8]. For exposure to ATP, the cells were superfused by means of a peristaltic pump with artificial perilymph containing 200 ÌM ATP and adjusted to 300 mosm with glucose.…”

Section: Analysis Of Ca 2+ Concentration In Isolated Es Epithelial Cellsmentioning

confidence: 99%

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Calcium Mobilization in Isolated Epithelial Cells of the Endolymphatic Sac

Arishige¹,

Takumida²,

Yajin³

1998

ORL

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Endolymphatic sac epithelial cells were isolated from the endolymphatic sac of the guinea pig by enzymatic and mechanical dissociation. The intracellular free calcium ion concentrations ([Ca²⁺]i) of the isolated cells were determined using the Ca²⁺-sensitive dye fura-2. The isolated cells were classified into two types, i.e. light and dark cells. In the resting state, [Ca²⁺]i in the cells was variable in both types of cells. In the presence of 200 µM ATP, there was a rapid rise in [Ca²⁺]i. These findings suggest that endolymphatic sac epithelial cells may have receptor-mediated Ca channels which may play an important role for a nerve-mediated local feedback system of the endolymphatic sac to regulate homeostasis of endolymph volume, pressure and electrolyte balance.

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Section: Discussionsupporting

confidence: 69%

Section: Isolation Of Es Epithelial Cellsmentioning

confidence: 99%

Section: Analysis Of Ca 2+ Concentration In Isolated Es Epithelial Cellsmentioning

confidence: 99%

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Calcium Mobilization in Isolated Epithelial Cells of the Endolymphatic Sac

Arishige¹,

Takumida²,

Yajin³

1998

ORL

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“…These and later findings were interpreted to indicate that calcium was released from intracellular stores which caused increased K 1 conductance, possibly through activation of muscarinic receptors, G-protein, and inositol 1,4,5-triphosphate (Shigemoto and Ohmori, 1991). In further studies of this calcium-induced, hyperpolarizing effect, Yamashita et al, (1993) demonstrated that application of ACh to isolated vestibular hair cells of guinea pigs causes a rapid rise in intracellular calcium.…”

Section: Possible Roles Of Vesiculated Presynaptic Processes: Relatementioning

confidence: 99%

Morphological evidence for local microcircuits in rat vestibular maculae

Ross

1997

J. Comp. Neurol.

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Previous studies suggested that intramacular, unmyelinated segments of vestibular afferent nerve fibers and their large afferent endings (calyces) on type I hair cells branch. Many of the branches (processes) contain vesicles and are presynaptic to type II hair cells, other processes, intramacular nerve fibers, and calyces. This study used serial section transmission electron microscopy and three-dimensional reconstruction methods to document the origins and distributions of presynaptic processes of afferents in the medial part of the adult rat utricular macula. The ultrastructural research focused on presynaptic processes whose origin and termination could be observed in a single micrograph. Results showed that calyces had 1) vesiculated, spine-like processes that invaginated type I cells and 2) other, elongate processes that ended on type II cells pre- as well as postsynaptically. Intramacular, unmyelinated segments of afferent nerve fibers gave origin to branches that were presynaptic to type II cells, calyces, calyceal processes, and other nerve fibers in the macula. Synapses with type II cells occurred opposite subsynaptic cisternae (C synapses); all other synapses were asymmetric. Vesicles were pleomorphic but were differentially distributed according to process origin. Small, clear-centered vesicles, approximately 40-60 nm in diameter, predominated in processes originating from afferent nerve fibers and basal parts of calyces. Larger vesicles approximately 70-120 nm in diameter having approximately 40-80 nm electron-opaque cores were dominant in processes originating from the necks of calyces. Results are interpreted to indicate the existence of a complex system of intrinsic feedforward (postsynaptic)-feedback (presynaptic) connections in a network of direct and local microcircuits. The morphological findings support the concept that maculae dynamically preprocess linear acceleratory information before its transmission to the central nervous system.

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“…These findings suggest that Ca 2+ is released from intracellular stores and causes increased K + conductance. In this framework, the efferent vestibular pathway would regulate hair cell threshold and gain by controlling intracellular Ca 2+ release from the cisternae, and therefore Ca 2+ -activated K + conductance (Shigemoto and Ohmori 1990;Fuchs and Murrow 1992;Yamashita et al 1993). If so, then differences in cisternal size would predict regional differences in Ca 2+ storage capabilities, as well as more generally in the regulation of cytosolic free Ca 2+ concentration.…”

Section: Discussionmentioning

confidence: 99%

Ultrastructural observations of efferent terminals in the crista Ampullaris of the toadfish, opsanus tau

Holstein

Martinelli

Boyle

et al. 2004

Experimental Brain Research

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The present study was conducted to visualize the ultrastructural features of vestibular efferent boutons in the oyster toadfish, Opsanus tau. The crista ampullaris of the horizontal semicircular canal was processed for and examined by routine transmission electron microscopy. The results demonstrate that such boutons vary in size and shape, and contain a heterogeneous population of lucent vesicles with scattered dense core vesicles. Efferent contacts with hair cells are characterized by local vesicle accumulations in the presynaptic terminal and a subsynaptic cistern in the postsynaptic region of the hair cell. Serial efferent to hair cell to afferent synaptic arrangements are common, particularly in the central portion of the crista. However, direct contacts between efferent terminals and afferent neurites were not observed in our specimens. The existence of serial synaptic contacts, often with a row of vesicles in the efferent boutons lining the efferent-afferent membrane apposition, suggests that the efferent influence on the crista may involve both synaptic and nonsynaptic, secretory mechanisms. Further, it is suggested that differences in more subtle aspects of synaptic architecture and/or transmitter and receptor localization and interaction may render the efferent innervation of the peripheral crista less effective in influencing sensory processing.

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Effects of Efferent Neurotransmitters on Intracellular Ca²⁺Concentration in Vestibular Hair Cells of the Guinea Pig

Cited by 20 publications

References 21 publications

Calcium Mobilization in Isolated Epithelial Cells of the Endolymphatic Sac

Calcium Mobilization in Isolated Epithelial Cells of the Endolymphatic Sac

Morphological evidence for local microcircuits in rat vestibular maculae

Ultrastructural observations of efferent terminals in the crista Ampullaris of the toadfish, opsanus tau

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Effects of Efferent Neurotransmitters on Intracellular Ca2+Concentration in Vestibular Hair Cells of the Guinea Pig

Cited by 20 publications

References 21 publications

Calcium Mobilization in Isolated Epithelial Cells of the Endolymphatic Sac

Calcium Mobilization in Isolated Epithelial Cells of the Endolymphatic Sac

Morphological evidence for local microcircuits in rat vestibular maculae

Ultrastructural observations of efferent terminals in the crista Ampullaris of the toadfish, opsanus tau

Contact Info

Product

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Effects of Efferent Neurotransmitters on Intracellular Ca²⁺Concentration in Vestibular Hair Cells of the Guinea Pig