Comparative transduction mechanisms of hair cells in the bullfrog utriculus. I. Responses to intracellular current

1994 ◽  
Vol 71 (2) ◽  
pp. 666-684 ◽  
Author(s):  
R. A. Baird
Keyword(s):  
B Cells ◽  
Hair Cell ◽  
Hair Cells ◽  
Hair Bundle ◽  
C Cells ◽  
Type B ◽  
Lateral Border ◽  
Utricular Macula ◽  
Type C ◽  
Current Steps

1. Hair cells in whole-mount in vitro preparations of the utricular macula of the bullfrog (Rana catesbeiana) were selected according to their macular location and hair bundle morphology. The voltage responses of selected hair cells to intracellular current steps and sinusoids in the frequency range of 0.5-200 Hz were studied with conventional intracellular recordings. 2. The utricular macula is divided into medial and lateral parts by the striola, a 75- to 100-microns zone that runs for nearly the entire length of the sensory macula near its lateral border. The striola is distinguished from flanking extrastriolar regions by the elevated height of its apical surface and the wider spacing of its hair cells. A line dividing hair cells of opposing polarities, located near the lateral border of the striola, separates it into medial and lateral parts. On average, the striola consists of five to seven medial and two to three lateral rows of hair cells. 3. Utricular hair cells were classified into four types on the basis of hair bundle morphology. Type B cells, the predominant hair cell type in the utricular macula, are small cells with short sterocilia and kinocilia 2-6 times as long as their longest stereocilia. These hair cells were found throughout the extrastriola and, more rarely, in the striolar region. Three other hair cell types were restricted to the striolar region. Type C cells, found primarily in the outer striolar rows, resemble enlarged versions of Type B hair cells. Type F cells have kinocilia approximately equal in length to their longest stereocilia and are restricted to the middle striolar rows. Type E cells, found only in the innermost striolar rows, have short kinocilia with prominent kinociliary bulbs. 4. The resting potential of 99 hair cells was -58.0 +/- 7.6 (SD) mV and did not vary significantly for hair cells in differing macular locations or with differing hair bundle morphology. The RN of hair cells, measured from the voltage response to current steps, varied from 200 to > 2,000 M omega and was not well correlated with cell size. On average, Type B cells had the highest RN, followed by Type F, Type E, and Type C cells. When normalized to their surface area, the membrane resistance of hair cells ranged from < 1,000 to > 10,000 k omega.cm2. The input capacitance of hair cells ranged from < 3 to > 15 pA, corresponding on average to a membrane capacitance of 0.8 +/- 0.2 pA/cm2.(ABSTRACT TRUNCATED AT 400 WORDS)

Comparative transduction mechanisms of hair cells in the bullfrog utriculus. II. Sensitivity and response dynamics to hair bundle displacement

1994 ◽  
Vol 71 (2) ◽  
pp. 685-705 ◽  
Author(s):  
R. A. Baird
Keyword(s):  
Hair Cells ◽  
Linear Displacement ◽  
Linear Range ◽  
Hair Bundle ◽  
Morphological Data ◽  
C Cells ◽  
Type B ◽  
Response Dynamics ◽  
Displacement Response ◽  
Type C

1. Hair cells in whole-mount in vitro preparations of the utricular macula of the bullfrog (Rana catesbeiana) were selected according to their macular location and hair bundle morphology. The sensitivity and response dynamics of selected hair cells to natural stimulation were examined by recording their voltage responses to step and sinusoidal hair bundle displacements applied to their longest stereocilia. 2. The voltage responses of 31 hair cells to sinusoidal hair bundle displacements were characterized by their gains and phases, taken with respect to peak hair bundle displacement. The gains of Type B and Type C cells at both 0.5 and 5.0 Hz were markedly lower than those of Type F and Type E cells. Phases, with the exception of Type C cells, lagged hair bundle displacement at 0.5 Hz. Type C cells had phase leads of 25-40 degrees. At 5.0 Hz, response phases in all cells were phase lagged with respect to those at 0.5 Hz. Type C cells had larger gains and smaller phase leads at 5.0 Hz than at 0.5 Hz, suggesting the presence of low-frequency adaptation. 3. Displacement-response curves, derived from the voltage responses to 5.0-Hz sinusoids, were sigmoidal in shape and asymmetrical, with the depolarizing response having a greater magnitude and saturating less abruptly than the hyperpolarizing response. When normalized to their largest displacement the linear ranges of these curves varied from < 0.5 to 1.25 microns and were largest in Type B and smallest in Type F and Type E cells. Sensitivity, defined as the slope of the normalized displacement-response curve, was inversely correlated with linear range. 4. The contribution of geometric factors associated with the hair bundle to linear range and sensitivity were predicted from realistic models of utricular hair bundles created using morphological data obtained from light and electron microscopy. Three factors, including 1) the inverse ratio of the lengths of the kinocilium and longest stereocilia, representing the lever arm between kinociliary and stereociliary displacement; 2) tip link extension/linear displacement, largely a function of stereociliary height and separation; and 3) stereociliary number, an estimate of the number of transduction channels, were considered in this analysis. The first of these factors was quantitatively more important than the latter two factors and their total contribution was largest in Type B and Type C cells. Theoretical models were also used to calculate the relation between rotary and linear displacement.(ABSTRACT TRUNCATED AT 400 WORDS)

Loss of hamster Leydig cells during regression after exposure to a short photoperiod

2018 ◽  
Vol 30 (8) ◽  
pp. 1137 ◽  
Author(s):  
E. Beltrán-Frutos ◽  
V. Seco-Rovira ◽  
J. Martínez-Hernández ◽  
C. Ferrer ◽  
L. M. Pastor
Keyword(s):  
B Cells ◽  
Leydig Cells ◽  
Light And Electron Microscopy ◽  
Type A ◽  
Nuclear Antigen ◽  
Control Group ◽  
C Cells ◽  
Type B ◽  
A Cells ◽  
Type C

The aim of the present study was to evaluate the changes that occur in hamster Leydig cells during regression. Animals were divided into control, mild regression (MR), strong regression (SR) and total regression (TR) groups. Leydig cells were characterised by light and electron microscopy. Terminal deoxyribonucleotidyl transferase-mediated dUTP–digoxigenin nick end-labelling (TUNEL) and proliferating cell nuclear antigen (PCNA) antibodies were used to detect apoptosis and proliferation respectively. Three types of Leydig cells (A, B and C) could be differentiated. Type A cells were small in size compared with Leydig cells from animals exposed to a long photoperiod, which was a result of a decreased cytoplasm and nucleus. Type B cells were even smaller than Type A cells in regression groups. Type C exhibited cytoplasm vacuolisation. The percentage of Type C cells from the control group was much lower than in the MR, SR and TR groups. (P < 0.05). In the SR and TR groups, there was a significant decrease in the percentage of Type B cells compared with the control and MR groups (P < 0.05). The total number of Leydig cells decreased during testicular regression (P < 0.05). The total number of Type A and B cells was significantly lower in the MR, SR and TR groups compared with the control group (P < 0.05). There were no significant differences in the proliferation and apoptosis index in the groups studied. The findings of the present study indicate that there are three types of Leydig cells (A, B and C) in all hamsters studied and that regression causes an increase in the number of Type C cells, so that the reduction in the number Leydig cells during the phases of regression studied must be the result of necrosis and/or necroptosis.

Separation of two bone cell populations from fetal rat calvaria and a study of their responses to parathyroid hormone and calcitonin

1983 ◽  
Vol 99 (3) ◽  
pp. 387-399 ◽  
Author(s):  
I. P. Braidman ◽  
D. C. Anderson ◽  
C. J. P. Jones ◽  
J. B. Weiss
Keyword(s):  
Alkaline Phosphatase ◽  
Parathyroid Hormone ◽  
Acid Phosphatase ◽  
B Cells ◽  
Adenylate Cyclase ◽  
Culture Medium ◽  
Cell Populations ◽  
C Cells ◽  
Type B ◽  
Type C

Bone cells released from perinatal rat calvaria by digestion with clostridial peptidase were separated into two distinct populations (designated types B and C) by equilibrium density centrifugation on a two-step gradient of Percoll. They were extensively characterized by light and electron microscopy and for behaviour in culture, acid and alkaline phosphatase activity, collagen synthesis, collagenase secretion and adenylate cyclase response to parathyroid hormone (PTH) and calcitonin. Type C cells were predominantly large with up to seven nuclei and an unusual cytoplasmic appearance in cytocentrifuge preparations. They did not proliferate in culture and we have established culture conditions which prevented their overgrowth by contaminating proliferative cells. In culture these cells had low alkaline and high acid phosphatase and high aryl sulphatase activity, and synthesized little collagen. In contrast type B cells were mostly smaller and many had irregular cytoplasmic projections. In culture they became polygonal in shape, proliferated rapidly, and reached confluence in 4–5 days. These were low in aryl sulphatase and acid phosphatase, high in alkaline phosphatase activity, and synthesized labelled collagen actively with [3H]proline and ascorbic acid included in the culture medium. The two cell populations were found to differ in culture in two important further respects. First, the type C cells showed an adenylate cyclase response to calcitonin but not to PTH, while the converse was true for type B cells; this was so over at least a 20-fold range of isobutylmethyl xanthine concentration. Secondly, type C cells in culture secreted an active collagenolytic enzyme. Type B cells secreted much lower levels of a predominantly latent collagenase which required activation by mersalyl. Co-culture of type C and type B cells led to a marked reduction in the content of active collagenase in the culture medium.

In vitro associative conditioning of Hermissenda: cumulative depolarization of type B photoreceptors and short-term associative behavioral changes

1987 ◽  
Vol 57 (6) ◽  
pp. 1639-1668 ◽  
Author(s):  
J. Farley ◽  
D. L. Alkon
Keyword(s):  
Nervous System ◽  
B Cells ◽  
Hair Cell ◽  
B Cell ◽  
Behavioral Changes ◽  
Type B ◽  
Short Term ◽  
Phototactic Behavior ◽  
Optic Ganglion

Cumulative depolarization of Hermissenda type B photoreceptors, a short-term neural correlate of associative learning, was produced by simulating associative training in the isolated nervous system (in vitro conditioning). This simulation entailed stimulation and recording from three classes of neurons normally affected by the associative training procedure: a type B photoreceptor, the silent/excitatory (S/E) optic ganglion cell, and a statocyst caudal hair cell. Exposure of the isolated nervous system to five simultaneous pairings of light and current-induced impulse activity of the caudal hair cell resulted in an average 10-mV depolarization of type B cells. Cumulative depolarization was found to be pairing specific, to occur with a minimal number of training trials, and was paralleled by short-term pairing-specific changes in phototactic behavior for the intact animal. Two important determinants of cumulative depolarization were found to be the magnitude and duration of the long-lasting depolarization (LLD) response of type B cells to light, and a pairing-specific synaptic facilitation of the LLD response. The synaptic facilitation arose from two distinct sources: increased excitatory postsynaptic potential (EPSP) feedback on B cells following light and caudal hair cell stimulation pairings, and disinhibition of the type B photoreceptor following pairings. The S/E optic ganglion cell was found to be a potent regulator of B cell EPSPs. Cumulative depolarization was substantially reduced when the S/E cell was hyperpolarized throughout the course of pairings. Conversely, pairings of light with depolarizing current stimulation of the S/E cell were sufficient to produce cumulative depolarization of B cells. Precluding disinhibition of the B cell from the caudal hair cell was also found to attenuate cumulative depolarization. Additional constraints, inherent to the neural organization of the visual and statocyst neural systems were found to further limit the degree of cumulative depolarization. Among the most important of these were the interpairing interval and light intensity. Exposure of intact animals of five pairings of light and rotation resulted in short-term suppression of phototactic behavior. Like the cumulative depolarization of B cells with in vitro conditioning procedures, these changes were relatively pairing specific and persisted for comparable durations of time. Cumulative depolarization of B cells appears to be an important initial step in the production of long-term associative neural and behavioral changes in Hermissenda.

Physiological properties of rat ventral pallidal neurons recorded intracellularly in vivo

1996 ◽  
Vol 75 (4) ◽  
pp. 1432-1443 ◽  
Author(s):  
A. Lavin ◽  
A. A. Grace
Keyword(s):  
B Cells ◽  
Nucleus Accumbens ◽  
Action Potential ◽  
Type A ◽  
C Cells ◽  
Postsynaptic Potentials ◽  
A Cells ◽  
Type C ◽  
Stimulation Of

1. The physiology of ventral pallidal (VP) cells was investigated using in vivo intracellular recording and staining techniques in adult rats. Based on electrophysiological criteria, three different types of cells were found: type A cells, which fired phasic spikes that did not exhibit a substantial afterhyperpolarization (AHP), type B cells, which exhibited a slow ramplike depolarization that preceded the short-duration action potential; the spike was followed by a prominent AHP, and type C cells, which were the only cells that fired spikes in couplets or bursts, with the spikes in a burst exhibiting a progressive increase in duration and a decrease in amplitude. These cells also exhibited a rebound low threshold spikelike event. Furthermore, 18% of the VP cells recorded exhibited a slow subthreshold oscillation of the membrane potential (< 1 Hz). 2. The response of VP cells to stimulation of fibers arising from the prefrontal cortex, nucleus accumbens, and mediodorsal thalamic nucleus (MD) was examined. In contrast to our initial predictions, all cells responded to nucleus accumbens stimulation with excitation. Type A and B cells responded to nucleus accumbens stimulation with excitation and to MD stimulation with antidromic-like responses, orthodromic excitation, or evoked inhibitory postsynaptic potentials. Only type A cells responded to prefrontal cortical stimulation. Type C cells only responded to stimulation of the nucleus accumbens, which resulted in evoked excitatory postsynaptic potentials. 3. The cells in the VP therefore can be segregated into three physiologically defined groups according to action potential discharge patterns and their response to afferent fiber stimulation.

The coding of sound pressure and frequency in cochlear hair cells of the terrapin

1978 ◽  
Vol 203 (1151) ◽  
pp. 209-218 ◽  
Keyword(s):  
Hair Cell ◽  
Hair Cells ◽  
Characteristic Frequency ◽  
Voltage Response ◽  
Recording Electrode ◽  
Small Current ◽  
Cochlear Hair Cells ◽  
Damped Oscillations ◽  
Current Steps ◽  
Two Stages

Intracellular recordings have been made from single hair cells in the cochlea of the terrapin, and the site of recording has been verified by injection of a fluorescent dye through the recording electrode. A hair cell gives periodic voltage responses graded with the intensity and frequency of the sound stimulus, and produces the largest response at its characteristic frequency. When small current steps are injected through the recording electrode, the voltage response of the cell exhibits damped oscillations at its characteristic frequency. The results are consistent with the idea that the cochlear frequency selectivity arises in two stages and it is suggested that the second stage resides within the hair cell itself.

scholarly journals The development of cooperative channels explains the maturation of hair cell’s mechanotransduction

2019 ◽  
Author(s):  
Francesco Gianoli ◽  
Thomas Risler ◽  
Andrei S. Kozlov
Keyword(s):  
Ion Channels ◽  
Hair Cell ◽  
Inner Ear ◽  
Hair Cells ◽  
Hair Bundle ◽  
Mechanical Stimuli ◽  
Biophysical Properties ◽  
Tip Link ◽  
Fast Adaptation ◽  
Kinetics Of

ABSTRACTHearing relies on the conversion of mechanical stimuli into electrical signals. In vertebrates, this process of mechano-electrical transduction (MET) is performed by specialized receptors of the inner ear, the hair cells. Each hair cell is crowned by a hair bundle, a cluster of microvilli that pivot in response to sound vibrations, causing the opening and closing of mechanosensitive ion channels. Mechanical forces are projected onto the channels by molecular springs called tip links. Each tip link is thought to connect to a small number of MET channels that gate cooperatively and operate as a single transduction unit. Pushing the hair bundle in the excitatory direction opens the channels, after which they rapidly reclose in a process called fast adaptation. It has been experimentally observed that the hair cell’s biophysical properties mature gradually during postnatal development: the maximal transduction current increases, sensitivity sharpens, transduction occurs at smaller hair-bundle displacements, and adaptation becomes faster. Similar observations have been reported during tip-link regeneration after acoustic damage. Moreover, when measured at intermediate developmental stages, the kinetics of fast adaptation varies in a given cell depending on the magnitude of the imposed displacement. The mechanisms underlying these seemingly disparate observations have so far remained elusive. Here, we show that these phenomena can all be explained by the progressive addition of MET channels of constant properties, which populate the hair bundle first as isolated entities, then progressively as clusters of more sensitive, cooperative MET channels. As the proposed mechanism relies on the difference in biophysical properties between isolated and clustered channels, this work highlights the importance of cooperative interactions between mechanosensitive ion channels for hearing.SIGNIFICANCEHair cells are the sensory receptors of the inner ear that convert mechanical stimuli into electrical signals transmitted to the brain. Sensitivity to mechanical stimuli and the kinetics of mechanotransduction currents change during hair-cell development. The same trend, albeit on a shorter timescale, is also observed during hair-cell recovery from acoustic trauma. Furthermore, the current kinetics in a given hair cell depends on the stimulus magnitude, and the degree of that dependence varies with development. These phenomena have so far remained unexplained. Here, we show that they can all be reproduced using a single unifying mechanism: the progressive formation of channel pairs, in which individual channels interact through the lipid bilayer and gate cooperatively.

scholarly journals Multiple PDZ domain protein maintains patterning of the apical cytoskeleton in sensory hair cells

Development ◽  
2021 ◽  
Author(s):  
Amandine Jarysta ◽  
Basile Tarchini
Keyword(s):  
Hair Cell ◽  
Hair Cells ◽  
Critical Role ◽  
Pdz Domain ◽  
Hair Bundle ◽  
Structural Defects ◽  
Sensory Hair ◽  
High Frequencies ◽  
Sensory Hair Cells ◽  
Sound Transduction

Sound transduction occurs in the hair bundle, the apical compartment of sensory hair cells in the inner ear. The hair bundle is formed of actin-based stereocilia aligned in rows of graded heights. It was previously shown that the GNAI-GPSM2 complex is part of a developmental blueprint that defines the polarized organization of the apical cytoskeleton in hair cells, including stereocilia distribution and elongation. Here we report a novel and critical role for Multiple PDZ domain (MPDZ) protein during apical hair cell morphogenesis. We show that MPDZ is enriched at the hair cell apical membrane along with MAGUK p55 subfamily member 5 (MPP5/PALS1) and the Crumbs protein CRB3. MPDZ is required there to maintain the proper segregation of apical blueprints proteins, including GNAI-GPSM2. Loss of the blueprint coincides with misaligned stereocilia placement in Mpdz mutant hair cells, and results in permanently misshapen hair bundles. Graded molecular and structural defects along the cochlea can explain the profile of hearing loss in Mpdz mutants, where deficits are most severe at high frequencies.

scholarly journals Par3 is essential for the establishment of planar cell polarity of inner ear hair cells

2019 ◽  
Vol 116 (11) ◽  
pp. 4999-5008 ◽  
Author(s):  
Andre Landin Malt ◽  
Zachary Dailey ◽  
Julia Holbrook-Rasmussen ◽  
Yuqiong Zheng ◽  
Arielle Hogan ◽  
...  
Keyword(s):  
Hair Cell ◽  
Inner Ear ◽  
Cell Polarity ◽  
Hair Cells ◽  
Planar Cell Polarity ◽  
Tissue Level ◽  
Hair Bundle ◽  
Nucleotide Exchange ◽  
Genetic Mosaic ◽  
Pcp Signaling

In the inner ear sensory epithelia, stereociliary hair bundles atop sensory hair cells are mechanosensory apparatus with planar polarized structure and orientation. This is established during development by the concerted action of tissue-level, intercellular planar cell polarity (PCP) signaling and a hair cell-intrinsic, microtubule-mediated machinery. However, how various polarity signals are integrated during hair bundle morphogenesis is poorly understood. Here, we show that the conserved cell polarity protein Par3 is essential for planar polarization of hair cells. Par3 deletion in the inner ear disrupted cochlear outgrowth, hair bundle orientation, kinocilium positioning, and basal body planar polarity, accompanied by defects in the organization and cortical attachment of hair cell microtubules. Genetic mosaic analysis revealed that Par3 functions both cell-autonomously and cell-nonautonomously to regulate kinocilium positioning and hair bundle orientation. At the tissue level, intercellular PCP signaling regulates the asymmetric localization of Par3, which in turn maintains the asymmetric localization of the core PCP protein Vangl2. Mechanistically, Par3 interacts with and regulates the localization of Tiam1 and Trio, which are guanine nucleotide exchange factors (GEFs) for Rac, thereby stimulating Rac-Pak signaling. Finally, constitutively active Rac1 rescued the PCP defects in Par3-deficient cochleae. Thus, a Par3–GEF–Rac axis mediates both tissue-level and hair cell-intrinsic PCP signaling.

Structural changes, related to reproduction, in the hypothalamus and in the pars tuberalis of the rhesus monkey: Part I. The hypothalamus. Part II. The pars tuberalis

1969 ◽  
Vol 256 (809) ◽  
pp. 357-375 ◽  
Keyword(s):  
Menstrual Cycle ◽  
Rhesus Monkey ◽  
Blood Vessels ◽  
Median Eminence ◽  
Pars Tuberalis ◽  
C Cells ◽  
Type B ◽  
Iii Ventricle ◽  
Type C ◽  
The Brain

Certain cells lining a circumscribed area of the III ventricle of the rhesus monkey differ from those cells which constitute the characteristic ependymal lining of the brain. The specialized cells studied comprise a number of types which differ in their structure, ultrastructure and staining affinities; all demonstrate features which are generally associated with active secretion and/or absorption. A group of such cells, which form a limited area of the latero-ventral walls of the anterior hypothalamus, have long processes which extend to the walls of the blood vessels in the median eminence. The evidence indicates that many of these cells, here described as Type B or tanycyte cells, secrete their products into the primary capillary network of the pituitary portal system. Another group of cells, here described as Type C and C' cells are found in a slightly more posterior position lining the floor of the ventricle; as yet there are no indications that these may secrete into blood vessels in the median eminence. Some of the specialized cells lining the III ventricle (Types B and C') showed changes in relation to reproductive activity: No such changes were observed in Type C cells nor in the characteristic ependymal cells (Type A) found elsewhere. Studies on normal and experimental male and female monkeys showed that Type B tanycyte cells differed in males and females and altered during the menstrual cycle in the female. Following ovariectomy these cells showed regressive changes but returned to a normal appearance after a single injection of oestradiol. In view of the close spatial relationship of the tanycyte ependyma to cells of the pars tuberalis it was interesting to note that pars tuberalis cells also altered in relation to the menstrual cycle. The evidence presented accords with the view that certain cells which line the III ventricle of the brain and have prolongations extending to pituitary blood vessels, thus linking the cerebrospinal fluid and the blood system in the region of the pituitary, may play a role in the regulation of pituitary function and thereby constitute an important neuro-endocrine system.

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