Vestibular Type I and Type II Hair Cells. 2: Morphometric Comparisons of Dissociated Pigeon Hair Cells

1997 ◽  
Vol 7 (5) ◽  
pp. 407-420
Author(s):  
Anthony J. Ricci ◽  
Stephen L. Cochran ◽  
Katherine J. Rennie ◽  
Manning J. Correia
Keyword(s):  
Hair Cells ◽  
Semicircular Canals ◽  
Columba Livia ◽  
Hair Bundle ◽  
Type I ◽  
Type Ii ◽  
Cell Groups ◽  
Hair Bundles

Morphometric properties of solitary hair cells dissociated from the semicircular canals (SCC), utricles (UTR), and lagenas (LAG) of adult white king pigeons, Columba livia, were compared. Measurements were made of the cell body, cuticular plate and hair bundle. Cells were divided into two groups: type 1 (group 1) was predominantly type I hair cells, and type 2 (group 3) was primarily type II hair cells. Comparisons are made initially between end organs for each group. A subpopulation of short otolith hair cells was identified. Quantitative comparisons between isolated type 1 and type 2 hair cells demonstrated that type 1 hair cells were more homogeneous both within and between vestibular end organs; while they had shorter, thinner neck regions, narrower apical surfaces, with longer and thinner bodies than did type 2 hair cells. Generally, for both type 1 and type 2 hair cells, two different hair bundle shapes were present, those (unimodal) with a single sharp taper from longest to shortest stereocilia, and those (bimodal) with an initial steep tape-followed by a less steep taper. An additional subtype of type 1 hair cells with short hair bundles was identified. SCC hair cells have fewer hair bundles with bimodal tapers across all cell groups when compared to UTR or LAG. All cell subtypes identified for dissociated hair cells were corroborated using histologic sections.

Potassium currents in mammalian and avian isolated type I semicircular canal hair cells

1994 ◽  
Vol 71 (1) ◽  
pp. 317-329 ◽  
Author(s):  
K. J. Rennie ◽  
M. J. Correia
Keyword(s):  
Membrane Potential ◽  
Hair Cells ◽  
Potassium Current ◽  
Columba Livia ◽  
Membrane Properties ◽  
Delayed Rectifier ◽  
Type I ◽  
Type Ii ◽  
Current Clamp ◽  
Whole Cell

1. Type I vestibular hair cells were isolated from the cristae ampullares of the semicircular canals of the Mongolian gerbil (Meriones unguiculatus) and the white king pigeon (Columba livia). Dissociated type I cells were distinguished from type II hair cells by their neck to plate ratio (NPR) and their characteristic amphora shape. 2. The membrane properties of gerbil and pigeon type I hair cells were studied in whole-cell voltage- and current-clamp using the perforated patch technique with amphotericin B as the perforating agent. 3. In whole-cell current-clamp, the average zero-current potential, Vz, measured for pigeon type I hair cells, was -70 +/- 7 (SD) mV (n = 18) and -71 +/- 11 mV (n = 83) for gerbil type I hair cells. 4. At Vz, for both gerbil and pigeon type I hair cells, a potassium current (IKI) was > or = 50% activated. This current deactivated rapidly when the membrane potential was hyperpolarized below -90 mV. 5. IKI was blocked by externally applied 4-aminopyridine (4-AP) (5 mM) and by internally applied 20 mM tetraethylammonium (TEA). It was also reduced when 4 mM barium was present in the external solution. The degree of block by barium increased as the membrane potential became more positive. External cesium (5 mM) blocked the inward component of IKI. When IKI was pharmacologically blocked, Vz depolarized by approximately 40 mV. Therefore IKI appears to be a delayed rectifier and to set the more negative Vz noted for isolated type I hair cells when compared to isolated type II hair cells, which do not have IKI. 6. A second, smaller potassium current was present at membrane potential depolarizations above -40 mV. This current was blocked by 30-50 mM, externally applied TEA, 100 microM quinidine, 100 nM apamin, but not 100 nM charybdotoxin, indicating that this is a calcium-activated potassium current, IK(Ca), different from the maxi-K calcium-activated potassium current found in most other hair cells.

scholarly journals The Activation of Type 1 and Type 2 Plasminogen by Type I and Type II Tissue Plasminogen Activator

1995 ◽  
Vol 270 (7) ◽  
pp. 3261-3267 ◽  
Author(s):  
Kazuya Mori ◽  
Raymond A. Dwek ◽  
A. Kristina Downing ◽  
Ghislain Opdenakker ◽  
Pauline M. Rudd
Keyword(s):  
Plasminogen Activator ◽  
Tissue Plasminogen Activator ◽  
Type I ◽  
Type Ii ◽  
Tissue Plasminogen

Alternative splicing of human insulin receptor gene (INSR) in type I and type II skeletal muscle fibers of patients with myotonic dystrophy type 1 and type 2

2013 ◽  
Vol 380 (1-2) ◽  
pp. 259-265 ◽  
Author(s):  
Massimo Santoro ◽  
Marcella Masciullo ◽  
Davide Bonvissuto ◽  
Maria Laura Ester Bianchi ◽  
Fabrizio Michetti ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Receptor Gene ◽  
Type I ◽  
Myotonic Dystrophy Type 1 ◽  
Type Ii ◽  
Myotonic Dystrophy Type ◽  
Insulin Receptor Gene ◽  
Human Insulin Receptor

Na+ Currents in Vestibular Type I and Type II Hair Cells of the Embryo and Adult Chicken

2003 ◽  
Vol 90 (2) ◽  
pp. 1266-1278 ◽  
Author(s):  
S. Masetto ◽  
M. Bosica ◽  
M. J. Correia ◽  
O. P. Ottersen ◽  
G. Zucca ◽  
...  
Keyword(s):  
Cell Membrane ◽  
Hair Cells ◽  
Regional Distribution ◽  
Semicircular Canals ◽  
Voltage Response ◽  
Fast Time ◽  
Type I ◽  
Type Ii ◽  
Adult Chicken ◽  
Voltage Dependent

In birds, type I and type II hair cells differentiate before birth. Here we describe that chick hair cells, from the semicircular canals, begin expressing a voltage-dependent Na current ( INa) from embryonic day 14 (E14) and continue to express the current up to hatching (E21). During this period, INa was present in most (31/43) type I hair cells irrespective of their position in the crista, in most type II hair cells located far from the planum semilunatum (48/63), but only occasionally in type II hair cells close to the planum semilunatum (2/35). INa activated close to –60 mV, showed fast time- and voltage-dependent activation and inactivation, and was completely, and reversibly, blocked by submicromolar concentrations of tetrodotoxin ( Kd = 17 nM). One peculiar property of INa concerns its steady-state inactivation, which is complete at –60 mV (half-inactivating voltage = –96 mV). INa was found in type I and type II hair cells from the adult chicken as well, where it had similar, although possibly not identical, properties and regional distribution. Current-clamp experiments showed that INa could contribute to the voltage response provided that the cell membrane was depolarized from holding potentials more negative than –80 mV. When recruited, INa produced a significant acceleration of the cell membrane depolarization, which occasionally elicited a large rapid depolarization followed by a rapid repolarization (action-potential-like response). Possible physiological roles for INa in the embryo and adult chicken are discussed.

scholarly journals Diabetic Retinopathy and Central Corneal Thickness

2019 ◽  
Vol 3 (3) ◽  
Keyword(s):  
Diabetes Mellitus ◽  
Diabetic Retinopathy ◽  
Central Corneal Thickness ◽  
Corneal Thickness ◽  
Diabetic Patients ◽  
Type I ◽  
Type Ii ◽  
The Mean

Background: Diabetes mellitus (DM) is a metabolic disease that can lead to many ocular complications such as increased Central Corneal Thickness (CCT), cataracts, and diabetic retinopathy. The aim of this study was to compare the CCT between subjects with type I and type II diabetes. Method: This was a retrospective study which included subjects with diabetes (with and without Diabetic Retinopathy (DR)) aged between 18 to 80 years old. The data collected were type and duration of diabetes mellitus, diabetes treatment, glycated hemoglobin level, visual acuity, CCT, and intra ocular pressure. Subjects were divided into subgroup (with and without DR). Statistical program (SPSS) was used to compare the central corneal thickness between the groups. Result: A total of 205 subjects with type I (n=100) and type II (n=105) diabetes were included in this study. In type 1 DM, the mean CCT was 547.06±27.3 microns in patients with diabetic retinopathy (DR) and 533.85±26.8 microns in patients without DR. In type 2 DM, the mean CCT was 542.85±39.3 microns in patients with DR and 532.44±27.4 microns in patients without DR. The CCT in type 1 diabetic patients was higher in both groups (with and without DR) than the CCT in type 2 diabetic patients in both groups (with and without DR). However, this was not statistically significant. Conclusion: The type of diabetes mellitus did not affect CCT. The presence of diabetic retinopathy in either type I or type II diabetes mellitus can affect the measurements of CCT.

scholarly journals Current Response in CaV1.3–/– Mouse Vestibular and Cochlear Hair Cells

2021 ◽  
Vol 15 ◽  
Author(s):  
Marco Manca ◽  
Piece Yen ◽  
Paolo Spaiardi ◽  
Giancarlo Russo ◽  
Roberta Giunta ◽  
...  
Keyword(s):  
Hair Cells ◽  
Signal Transmission ◽  
Basolateral Membrane ◽  
Semicircular Canals ◽  
Type I ◽  
Current Response ◽  
Type Ii ◽  
Current Profile ◽  
Cochlear Hair Cells ◽  
Vestibular Hair Cells

Signal transmission by sensory auditory and vestibular hair cells relies upon Ca2+-dependent exocytosis of glutamate. The Ca2+ current in mammalian inner ear hair cells is predominantly carried through CaV1.3 voltage-gated Ca2+ channels. Despite this, CaV1.3 deficient mice (CaV1.3–/–) are deaf but do not show any obvious vestibular phenotype. Here, we compared the Ca2+ current (ICa) in auditory and vestibular hair cells from wild-type and CaV1.3–/– mice, to assess whether differences in the size of the residual ICa could explain, at least in part, the two phenotypes. Using 5 mM extracellular Ca2+ and near-body temperature conditions, we investigated the cochlear primary sensory receptors inner hair cells (IHCs) and both type I and type II hair cells of the semicircular canals. We found that the residual ICa in both auditory and vestibular hair cells from CaV1.3–/– mice was less than 20% (12–19%, depending on the hair cell type and age investigated) compared to controls, indicating a comparable expression of CaV1.3 Ca2+ channels in both sensory organs. We also showed that, different from IHCs, type I and type II hair cells from CaV1.3–/– mice were able to acquire the adult-like K+ current profile in their basolateral membrane. Intercellular K+ accumulation was still present in CaV1.3–/– mice during IK,L activation, suggesting that the K+-based, non-exocytotic, afferent transmission is still functional in these mice. This non-vesicular mechanism might contribute to the apparent normal vestibular functions in CaV1.3–/– mice.

Morphology of electrophysiologically identified myenteric neurons in the guinea pig rectum

1992 ◽  
Vol 262 (3) ◽  
pp. G545-G552 ◽  
Author(s):  
K. Tamura
Keyword(s):  
Guinea Pig ◽  
Circular Muscle ◽  
Type I ◽  
Type Ii ◽  
Fiber Tracts ◽  
Single Spike ◽  
Type 3 ◽  
Dogiel Type Ii

Dye-filled microelectrodes were used to investigate relations between morphology and electrophysiological behavior of neurons in the myenteric plexus of the guinea pig rectum. The neurons were divided into two general classes on the basis of morphology. The first class had smooth ovoid somas with multiple long processes that exited the ganglion in several different fiber tracts and fit the description of Dogiel type II neurons. Neurons of the second class had a single long process that exited the ganglion in a fiber tract and sometimes projected to the circular muscle. Neurons of the second class were subdivided into three groups. One of these had short club-shaped dendrites like Dogiel type I neurons. Another had short tapering filamentous processes. Neurons with a single long neurite that could not be classified made up the third group. AH/type 2 electrophysiological behavior was found in both general classes of neurons. S/type 1 electrophysiological behavior occurred only in neurons of the general class with a single long neurite. Type 3 electrical behavior, characterized by robust fast synaptic input in inexcitable neurons, was found only in the cells defined by a single long neurite. Single-spike neurons behaved electrophysiologically like AH/type 2 neurons without long-lasting hyperpolarizing afterpotentials. This behavior was limited to the class of neurons characterized morphologically by a single long neurite.

scholarly journals Steady-state stiffness of utricular hair cells depends on macular location and hair bundle structure

2011 ◽  
Vol 106 (6) ◽  
pp. 2950-2963 ◽  
Author(s):  
Corrie Spoon ◽  
W. J. Moravec ◽  
M. H. Rowe ◽  
J. W. Grant ◽  
E. H. Peterson
Keyword(s):  
Steady State ◽  
Hair Cells ◽  
Head Movement ◽  
Time Course ◽  
Hair Bundle ◽  
Type I ◽  
Response Dynamics ◽  
Functional Interpretation ◽  
Hair Bundles ◽  
Bundle Structure

Spatial and temporal properties of head movement are encoded by vestibular hair cells in the inner ear. One of the most striking features of these receptors is the orderly structural variation in their mechanoreceptive hair bundles, but the functional significance of this diversity is poorly understood. We tested the hypothesis that hair bundle structure is a significant contributor to hair bundle mechanics by comparing structure and steady-state stiffness of 73 hair bundles at varying locations on the utricular macula. Our first major finding is that stiffness of utricular hair bundles varies systematically with macular locus. Stiffness values are highest in the striola, near the line of hair bundle polarity reversal, and decline exponentially toward the medial extrastriola. Striolar bundles are significantly more stiff than those in medial (median: 8.9 μN/m) and lateral (2.0 μN/m) extrastriolae. Within the striola, bundle stiffness is greatest in zone 2 (106.4 μN/m), a band of type II hair cells, and significantly less in zone 3 (30.6 μN/m), which contains the only type I hair cells in the macula. Bathing bundles in media that break interciliary links produced changes in bundle stiffness with predictable time course and magnitude, suggesting that links were intact in our standard media and contributed normally to bundle stiffness during measurements. Our second major finding is that bundle structure is a significant predictor of steady-state stiffness: the heights of kinocilia and the tallest stereocilia are the most important determinants of bundle stiffness. Our results suggest 1) a functional interpretation of bundle height variability in vertebrate vestibular organs, 2) a role for the striola in detecting onset of head movement, and 3) the hypothesis that differences in bundle stiffness contribute to diversity in afferent response dynamics.

scholarly journals ELMOD1 stimulates ARF6-GTP hydrolysis to stabilize apical structures in developing vestibular hair cells

2017 ◽  
Author(s):  
Jocelyn F. Krey ◽  
Rachel A. Dumont ◽  
Philip A. Wilmarth ◽  
Larry L. David ◽  
Kenneth R. Johnson ◽  
...  
Keyword(s):  
Hair Cells ◽  
Membrane Trafficking ◽  
Apical Membrane ◽  
Small Gtpase ◽  
Hair Bundle ◽  
Type I ◽  
Sensory Hair ◽  
Cuticular Plate ◽  
Sensory Hair Cells ◽  
Hair Bundles

AbstractSensory hair cells require control of physical properties of their apical plasma membranes for normal development and function. Members of the ARF small GTPase family regulate membrane trafficking and cytoskeletal assembly in many cells. We identified ELMOD1, a guanine nucleoside triphosphatase activating protein (GAP) for ARF6, as the most highly enriched ARF regulator in hair cells. To characterize ELMOD1 control of trafficking, we used a mouse strain lacking functional ELMOD1 (roundabout; rda). In rda/rda mice, cuticular plates of utricle hair cells initially formed normally, then degenerated after postnatal day 5 (P5); large numbers of vesicles invaded the compromised cuticular plate. Hair bundles initially developed normally, but the cell’s apical membrane lifted away from the cuticular plate, and stereocilia elongated and fused. Membrane trafficking in type I hair cells, measured by FM1-43 dye labeling, was altered in rda/rda mice. Consistent with the proposed GAP role for ELMOD1, the ARF6 GTP/GDP ratio was significantly elevated in rda/rda utricles as compared to controls, and the level of ARF6-GTP was correlated with the severity of the rda/rda phenotype. These results suggest that conversion of ARF6 to its GDP-bound form is necessary for final stabilization of the hair bundle.Significance StatementAssembly of the mechanically sensitive hair bundle of sensory hair cells requires growth and reorganization of apical actin and membrane structures. Hair bundles and apical membranes in mice with mutations in the Elmod1 gene degenerate after formation, suggesting that the ELMOD1 protein stabilizes these structures. We show that ELMOD1 is a GTPase-activating protein in hair cells for the small GTP-binding protein ARF6, known to participate in actin assembly and membrane trafficking. We propose that conversion of ARF6 into the GDP-bound form in the apical domain of hair cells is essential for stabilizing apical actin structures like the hair bundle and ensuring that the apical membrane forms appropriately around the stereocilia.

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