Objective:This study aims to analyze the threshold changes in distortion product otoacoustic emissions（DPOAE） and auditory brainstem response（ABR） in adult Otof-/- mice before and after gene therapy, evaluating its effectiveness and exploring methods for assessing hearing recovery post-treatment. Methods:At the age of 4 weeks, adult Otof-/- mice received an inner ear injection of a therapeutic agent containing intein-mediated recombination of the OTOF gene, delivered via dual AAV vectors through the round window membrane（RWM）. Immunofluorescence staining assessed the proportion of inner ear hair cells with restored otoferlin expression and the number of synapses.Statistical analysis was performed to compare the DPOAE and ABR thresholds before and after the treatment. Results:AAV-PHP. eB demonstrates high transduction efficiency in inner ear hair cells. The therapeutic regimen corrected hearing loss in adult Otof-/- mice without impacting auditory function in wild-type mice. The changes in DPOAE and ABR thresholds after gene therapy are significantly correlated at 16 kHz. Post-treatment,a slight increase in DPOAE was observeds,followed by a recovery trend at 2 months post-treatment. Conclusion:Gene therapy significantly restored hearing in adult Otof-/- mice, though the surgical delivery may cause transient hearing damage. Precise and gentle surgical techniques are essential to maximize gene therapy's efficacy.
Mice ; Animals ; Otoacoustic Emissions, Spontaneous/physiology* ; Hearing/physiology* ; Ear, Inner ; Hearing Loss/therapy* ; Genetic Therapy ; Auditory Threshold/physiology* ; Evoked Potentials, Auditory, Brain Stem/physiology* ; Membrane Proteins

Heart rate variability (HRV) is governed by the autonomic nervous system (ANS) and is routinely used to estimate the state of body and mind. At the same time, recorded HRV features can vary substantially between people. A model for HRV that (1) correctly simulates observed HRV, (2) reliably functions for multiple scenarios, and (3) can be personalised using a manageable set of parameters, would be a significant step forward toward understanding individual responses to external influences, such as physical and physiological stress. Current HRV models attempt to reproduce HRV characteristics by mimicking the statistical properties of measured HRV signals. The model presented here for the simulation of HRV follows a radically different approach, as it is based on an approximation of the physiology behind the triggering of a heart beat and the biophysics mechanisms of how the triggering process—and thereby the HRV—is governed by the ANS. The model takes into account the metabolisation rates of neurotransmitters and the change in membrane potential depending on transmitter and ion concentrations. It produces an HRV time series that not only exhibits the features observed in real data, but also explains a reduction of low frequency band-power for physically or psychologically high intensity scenarios. Furthermore, the proposed model enables the personalisation of input parameters to the physiology of different people, a unique feature not present in existing methods. All these aspects are crucial for the understanding and application of future wearable health.
Autonomic Nervous System ; Biophysics ; Heart Rate ; Heart ; Membrane Potentials ; Neurotransmitter Agents ; Physiology ; Stress, Physiological ; Vital Signs

Cyproheptadine (CPH), a first-generation antihistamine, enhances the delayed rectifier outward K current (I) in mouse cortical neurons through a sigma-1 receptor-mediated protein kinase A pathway. In this study, we aimed to determine the effects of CPH on neuronal excitability in current-clamped pyramidal neurons in mouse medial prefrontal cortex slices. CPH (10 µmol/L) significantly reduced the current density required to generate action potentials (APs) and increased the instantaneous frequency evoked by a depolarizing current. CPH also depolarized the resting membrane potential (RMP), decreased the delay time to elicit an AP, and reduced the spike threshold potential. This effect of CPH was mimicked by a sigma-1 receptor agonist and eliminated by an antagonist. Application of tetraethylammonium (TEA) to block I channels hyperpolarized the RMP and reduced the instantaneous frequency of APs. TEA eliminated the effects of CPH on AP frequency and delay time, but had no effect on spike threshold or RMP. The current-voltage relationship showed that CPH increased the membrane depolarization in response to positive current pulses and hyperpolarization in response to negative current pulses, suggesting that other types of membrane ion channels might also be affected by CPH. These results suggest that CPH increases the excitability of medial prefrontal cortex neurons by regulating TEA-sensitive I channels as well as other TEA-insensitive K channels, probably I and inward-rectifier Kir channels. This effect of CPH may explain its apparent clinical efficacy as an antidepressant and antipsychotic.
Animals ; Cyproheptadine ; pharmacology ; Female ; Histamine H1 Antagonists ; pharmacology ; Membrane Potentials ; drug effects ; physiology ; Mice, Inbred C57BL ; Patch-Clamp Techniques ; Potassium Channel Blockers ; pharmacology ; Potassium Channels ; metabolism ; Prefrontal Cortex ; drug effects ; physiology ; Pyramidal Cells ; drug effects ; physiology ; Receptors, sigma ; agonists ; metabolism ; Tetraethylammonium ; pharmacology ; Tissue Culture Techniques

Amino Acid Substitution ; Drug Resistance, Multiple, Bacterial ; physiology ; Escherichia coli ; physiology ; Escherichia coli Proteins ; genetics ; metabolism ; Membrane Potentials ; physiology ; Models, Biological ; Multidrug Resistance-Associated Proteins ; genetics ; metabolism ; Mutation, Missense

Using intracellular potential recording technique in vivo, a series of hyperpolarizing and depolarizing currents at different intensities with a 50-ms duration were injected to somatic nociceptive neurons (SNNs) and somatic non-nociceptive neurons (SNNNs) in the anterior cingulate gyrus (ACG) of cats. The membrane electrical responses of the neurons were recorded, and the membrane electrical parameters of the neurons were calculated for comparative study on membrane electrical properties of SNNs and SNNNs of the ACG. A total of 188 ACG neurons from 57 cats were recorded. Among the 188 neurons, 172 (91.5%) and 16 (8.5%) were SNNs and SNNNs, respectively. The I-V curves of SNNs and SNNNs in the ACG were "S" shapes. When the absolute value of injected current intensity was less than or equal to 1 nA (≤ 1 nA), the I and V of I-V curves of both SNNs and SNNNs were linearly correlated (rSNNs = 0.99, rSNNNs = 0.99). When the absolute value of injected current intensity was more than 1 nA, both SNNs and SNNNs showed a certain inward or outward rectification behavior. Compared with SNNNs, SNNs had stronger rectification and lower adaptability (P < 0.01). With the increase of injected current intensity, the changes of frequency of discharges of SNNs were higher than those of SNNNs. In addition, the membrane resistance (Rm), the membrane capacity (Cm) and the time constant (τ) of SNNs were larger than those of SNNNs (P < 0.05 or P < 0.01). The differences in the membrane electrical properties between SNNs and SNNNs in the ACG suggested the disparity in neuronal cell size and cell membrane structure between them. The results of this study provided the experimental basis for deeply elucidating the mechanisms of somatic nociceptive sensation and characteristics on the membrane electrical aspects of ACG neurons.
Animals ; Cats ; Gyrus Cinguli ; cytology ; Membrane Potentials ; Neurons ; physiology ; Nociceptors ; physiology

OBJECTIVE: To investigate the feasibility of the round window stimulation electrical evoked auditory brainstem response (EABR) test, and optimize the parameters of recording and stimulation electrodes positions. METHOD: Ten healthy Hartley guinea pigs (20 ears) were used for the EABR test. The positive stimulation electrodes were placed into the round window niche, the animals were divided into three group according to the negative electrodes position, group A: the electric field was parallel with the projection of cochlear modiolus on the tympanic membrane, group B: the electric field was perpendicular to modiolus projection toward to the mastoid, group C: the electric field was perpendicular to modiolus projection toward to the zygomatic process. A series of optimized recording and stimulation parameters were uesed to reduce the electrical artifact. RESULT: All the 20 ears were normal in the ABR testing, and EABR waves were stable and well-differentiated in the EABR tests out of cochlea. But EABR waves of group A were more stable and differentiated than those of group B and C. In group A, the threshold of EABR was (0.54 ± 0.11) mA, and latency of wave III was (1.71 ± 0.05) ms when the stimulus intensity was 0.8 mA. In group B, the threshold of EABR was (0.62 ± 0.12) mA, and latency of wave III was (1.77 ± 0.03) ms. In group C, the threshold of EABR was (0.70 ± 0.14) mA, and latency of wave III was (1.86 ± 0.04)ms. The threshold of EABR and latency of wave III were significantly different among the three groups by statistic analysis. CONCLUSION EABR waves were stable and well-differentiated in the EABR tests out of cochlea. The EABR waves were recorded more stably and differentiated when the stimulating electrode and recording electrode were paralleled with the projection of modiolus on the tympanic membrane.
Animals ; Cochlea ; physiology ; Electric Stimulation ; Electrodes ; Evoked Potentials, Auditory, Brain Stem ; Guinea Pigs ; Round Window, Ear ; Tympanic Membrane

While the field of ATP synthase research has a long history filled with landmark discoveries, recent structural works provide us with important insights into the mechanisms that links the proton movement with the rotation of the Fo motor. Here, we propose a mechanism of unidirectional rotation of the Fo complex, which is in agreement with these new structural insights as well as our more general ΔΨ-driving hypothesis of membrane proteins: A proton path in the rotor-stator interface is formed dynamically in concert with the rotation of the Fo rotor. The trajectory of the proton viewed in the reference system of the rotor (R-path) must lag behind that of the stator (S-path). The proton moves from a higher energy site to a lower site following both trajectories simultaneously. The two trajectories meet each other at the transient proton-binding site, resulting in a relative rotation between the rotor and stator. The kinetic energy of protons gained from ΔΨ is transferred to the c-ring as the protons are captured sequentially by the binding sites along the proton path, thus driving the unidirectional rotation of the c-ring. Our ΔΨ-driving hypothesis on Fo motor is an attempt to unveil the robust mechanism of energy conversion in the highly conserved, ubiquitously expressed rotary ATP synthases.
Membrane Potentials ; physiology ; Membrane Proteins ; chemistry ; metabolism ; Mitochondrial Proton-Translocating ATPases ; chemistry ; metabolism ; Protein Conformation

Patch-clamp is used to study all sorts of ionic channels and their regulations with measuring pA current of cell ionic channel, but the fast capacitance (C-fast) compensation and slow capacitance (C-slow) compensation transient currents are caused by measuring objects and measuring instruments themselves which will change the properties of action potentials. The present paper firstly discusses the C-Fast transient currents affecting membrane capacitance and membrane potential, and then draws a conclusion that the changes of membrane potential affect the properties of action potential through analyzing the changes of membrane potential in H-H model. Based on this conclusion, we discuss the influence mechanisms mainly through the analysis of traditional C-fast compensation errors, and focus discussion on the shape of electrode capacitance affecting C-fast. This method can not only improve the compensation speed greatly, but also improve the compensation precision from the electrode shape as much as possible.
Action Potentials ; Electric Capacitance ; Ion Channels ; physiology ; Membrane Potentials ; Neurons ; cytology ; Patch-Clamp Techniques

OBJECTIVESK channels are existed in hearts of mouse, rat, and human. Biochemical evidence indicates that SK2 channels are expressed more in atrial than in ventricular tissue. SK channels are highly sensitive to the calcium concentration of the pipette solution. In the present study, performed whole-cell patch clamp was used to detect the calcium sensitivity of small conductance Ca(2+)-activated K+ channels (SK) currents between sinus ryhthm (SR) and auricular fibrillation (AF).

METHODSThe patients who accepted cardiopulmonary bypass were divided into two groups: 21 patients with SR and 8 patients with AF. The enzymatic dissociation method was improved according to the previous research by our lab. The performed whole cell patch-clamp technique was used to record SK2 currents in both SR and AF groups at room temperature.

RESULTSThe SK2 current density was (-2.92 +/- 0.35) pA/pF in SR group (n = 6) vs (-6.83 +/- 0.19) pA/pF in AF group at -130 mV (n = 3, P < 0.05). In SR group, the SK2 current densities in calcium concentration of the pipette solution are (-1.43 +/- 0.33) pA/pF (n = 7), (-2.92 +/- 0.35) pA/pF (n = 6), (-10.11 +/- 2.15) pA/pF (n = 8, P < 0.05); In AF group, the SK2 current densities are (-2.17 +/- 0.40) pA/pF (n = 4), (-6.83 +/- 0.19) pA/pF (n = 3), (-14.47 +/- 2.89 pA/pF) (n = 4, P < 0.05).

CONCLUSIONThe SK2 currents recorded in this experiment are voltage-independent, inwardly rectifying and apamin-sensitive. When the calcium concentration of the pipette solution is 5 x 10(-7) mol/L, SK2 current density in AF group are significantly larger than those in SR group. It suggests that SK currents involve the cardiomyocytes electric remodeling in AF. In AF group, the SK2 currents are more sensitive to free calcium ion. It shows that the increased sensitivity of SK2 currents to the calcium contribute to the occurrence and maintenance of AF.

Atrial Fibrillation ; metabolism ; physiopathology ; Calcium ; metabolism ; Cells, Cultured ; Heart Atria ; metabolism ; Humans ; Membrane Potentials ; physiology ; Myocytes, Cardiac ; metabolism ; Patch-Clamp Techniques ; Potassium Channels, Calcium-Activated ; physiology

Spontaneous, rhythmical contractions, or vasomotion, can be recorded from cerebral vessels under both normal physiological and pathophysiological conditions. We investigated the cellular mechanisms underlying vasomotion in the cerebral basilar artery (BA) of Wistar rats. Pressure myograph video microscopy was used to study the changes in cerebral artery vessel diameter. The main results of this study were as follows: (1) The diameters of BA and middle cerebral artery (MCA) were 314.5±15.7 μm (n=15) and 233.3±10.1 μm (n=12) at 10 mmHg working pressure (P<0.05), respectively. Pressure-induced vasomotion occurred in BA (22/28, 78.6%), but not in MCA (4/31, 12.9%) from 0 to 70 mmHg working pressure. As is typical for vasomotion, the contractile phase of the response was more rapid than the relaxation phase; (2) The frequency of vasomotion response and the diameter were gradually increased in BA from 0 to 70 mmHg working pressure. The amplitude of the rhythmic contractions was relatively constant once stable conditions were achieved. The frequency of contractions was variable and the highest value was 16.7±4.7 (n=13) per 10 min at 60 mmHg working pressure; (3) The pressure-induced vasomotion of the isolated BA was attenuated by nifedipine, NFA, 18β-GA, TEA or in Ca(2+)-free medium. Nifedipine, NFA, 18β-GA or Ca(2+)-free medium not only dampened vasomotion, but also kept BA in relaxation state. In contrasts, TEA kept BA in contraction state. These results suggest that the pressure-induced vasomotion of the isolated BA results from an interaction between Ca(2+)-activated Cl(-) channels (CaCCs) currents and K(Ca) currents. We hypothesize that vasomotion of BA depends on the depolarizing of the vascular smooth muscle cells (VSMCs) to activate CaCCs. Depolarization in turn activates voltage-dependent Ca(2+) channels, synchronizing contractions of adjacent cells through influx of extracellular calcium and the flow of calcium through gap junctions. Subsequent calcium-induced calcium release from ryanodine-sensitive stores activates K(Ca) channels and hyperpolarizes VSMCs, which provides a negative feedback loop for regenerating the contractile cycle.
Animals ; Basilar Artery ; cytology ; metabolism ; physiology ; Chloride Channels ; metabolism ; Female ; Male ; Membrane Potentials ; physiology ; Muscle, Smooth, Vascular ; cytology ; metabolism ; Myocytes, Smooth Muscle ; cytology ; metabolism ; Potassium Channels, Calcium-Activated ; metabolism ; Rats ; Rats, Wistar ; Vasoconstriction ; physiology ; Vasodilation ; physiology