Animals ; Blood Vessels ; pathology ; ultrastructure ; Cochlea ; blood supply ; Female ; Male ; Rats ; Rats, Inbred SHR ; Rats, Wistar

Animals ; Arteries ; metabolism ; Cochlea ; blood supply ; Cystathionine gamma-Lyase ; genetics ; Rats ; Rats, Sprague-Dawley

To investigate the effects of the free radical, 1,1-Diphenyl-2-picylhydrazyl, on cochlear blood flow, 20 guinea pigs were divided into 3 groups at random, 6 for control group, 6 for 1 mmol/L group and 8 for 0.1 mmol/L group. 2 microliters vehicle or drugs were dropped into round window membrane (RWM). Cochlear microcirculation was monitored by laser Doppler flowmeter (LDF), and mean arterial blood flow (MABP), which was transferred by pressure conductor sensor and preamplifier, was simultaneously recorded on the computer. Our results showed that MABP was stable throughout the experiment. Cochlear blood flow (CBF) increased by 10.32% (P < 0.05) in 1 mmol/L group, and decreased by 4.89% in 0.1 mmol/L group (P < 0.05). In control group cochlear microcirculation showed no significant changes. It is concluded that DPPH exerted effects on cochlear microcirculation.
Blood Flow Velocity ; Cochlea/*blood supply ; Free Radicals/pharmacology ; Laser-Doppler Flowmetry ; Microcirculation/drug effects ; Picrates/*pharmacology ; Random Allocation

Arterioles are major contributors to the control of systemic blood pressure and local blood flow. In this study, we compared electrophysiological properties of vascular smooth muscle cells (VSMCs) in anterior inferior cerebellar artery (AICA), mesenteric artery (MA) and spiral modiolar artery (SMA) by intracellular microelectrode recording and whole-cell patch clamp recording techniques. Results were shown as below: (1) Intracellular microelectrode recordings were made from VSMCs in AICA, MA and SMA with resting potentials of (-68±1.8) (n=65), (-71±2.4) (n=80) and (-66±2.9) mV (n=58), respectively. There was no significant difference in resting potentials among arterioles. (2) The membrane capacitance and membrane conductance in situ cells were much larger than those in dispersed smooth muscle cells by whole-cell recording techniques, and there was significant difference among arterioles, which were in the order: MA>AICA>SMA. After application of gap junction blocker 2-APB (100 μmol/L), the membrane capacitance and membrane conductance in situ cells were very close with those in single smooth muscle cells. (3) The I/V relation of whole-cell current of dissociated smooth muscle cells (AICA, MA and SMA) showed a prominent outward rectification, and the currents were substantially inhibited by 1 mmol/L 4-AP or 10 mmol/L TEA. When the command voltage was +40 mV, the current densities of VSMCs in AICA, MA and SMA were (26±2.0), (24±1.7) and (18±1.3) pA/pF respectively. SMA showed significant difference in the current density from AICA and MA respectively. These results suggest that the electrophysiological properties of coupling strength of gap junction and current density of smooth muscle cells are different among arterioles in the guinea pig.
Animals ; Arterioles ; cytology ; physiology ; Cerebellum ; blood supply ; Cochlea ; blood supply ; Electrophysiological Phenomena ; Female ; Guinea Pigs ; Male ; Mesenteric Arteries ; cytology ; Muscle, Smooth, Vascular ; cytology ; physiology

OBJECTIVEA variety of inner ear disease is related to microcirculation disturbance of inner ear, but smooth muscle cells (SMC) and endothelial cells (EC) of the spiral modiolar artery (SMA), which is the main blood supply to the inner ear, physiological feature is not very clear.

METHODSIn this study, two-intracellular microelectrode recording technique and cell staining techniques to study the SMC and EC resting membrane potential characteristics and communication links between cells of SMA.

RESULTSStudy found that SMC and EC have high and low resting membrane potential state, two state of the resting membrane potential of cells to ACh and high K+ response is completely different. The different types of cells, EC-EC, SMC-SMC and SMC-EC, can simultaneously record by two-microelectrode, two cell resting membrane potential can also be a double-high RP, double-low RP and one high- and one low- RP. Experiment recorded in one high- and one low- RP are the SMC-EC types, and ECs initial membrane potential are high potential, SMCs membrane potential are low initial potential. The double-high and double-low RP can be SMC-SMC or EC-EC or SMC-EC types.

CONCLUSIONThe results show that SMC and EC in the 0.3 - 0.5 mm range, similar type of cells have very good communication, can function together to maintain good and consistent, heterogeneous cell performance is more different.

Animals ; Arteries ; cytology ; Cochlea ; blood supply ; physiology ; Endothelial Cells ; physiology ; Guinea Pigs ; Membrane Potentials ; physiology ; Myocytes, Smooth Muscle ; physiology

OBJECTIVETo observe the effects of different shear stresses on the morphological changes in cochlear microvascular endothelial cells cultured in vitro so as to enrich the mechanism of the blood-labyrinth barrier.

METHODSThe morphological photos of cochlear microvascular endothelial monolayer cells were obtained with the hydrodynamic system design and the morphological parameters such as Pyx and Q were detected.

RESULTSThrough digestion with collagenase type I, the monolayer cells of cochlear microvascular endothelial monolayer were obtained. As to cochlear microvascular endothelial cells in guinea pigs, no morphological changes of the cells were found when shear stresses of 0. 0883 Pa acting for 24 h. When shear stress was 0.1184 Pa acting for 8 h, compliant changes from former disorderliness into orderliness happened following the direction of the flowing liquid of the cellular morphology. The changing tendency was in a time-dependent manner.

CONCLUSIONSCochlear microvascular endothelial cells in guinea pigs after the effect of shear stress are morphologically different from statically cultured endothelial cells. Range of the shear stress that cochlear microvascular endothelial cells can tolerate is little.

Animals ; Cells, Cultured ; Cochlea ; blood supply ; Endothelial Cells ; cytology ; Endothelium, Vascular ; cytology ; Guinea Pigs ; Shear Strength ; Stress, Mechanical

To investigate the effects of the free radical, 1,1-Diphenyl-2-picylhydrazyl, on cochlear blood flow, 20 guinea pigs were divided into 3 groups at random, 6 for control group, 6 for 1 mmol/L group and 8 for 0.1 mmol/L group. 2 microliters vehicle or drugs were dropped into round window membrane (RWM). Cochlear microcirculation was monitored by laser Doppler flowmeter (LDF), and mean arterial blood flow (MABP), which was transferred by pressure conductor sensor and preamplifier, was simultaneously recorded on the computer. Our results showed that MABP was stable throughout the experiment. Cochlear blood flow (CBF) increased by 10.32% (P < 0.05) in 1 mmol/L group, and decreased by 4.89% in 0.1 mmol/L group (P < 0.05). In control group cochlear microcirculation showed no significant changes. It is concluded that DPPH exerted effects on cochlear microcirculation.
Animals ; Biphenyl Compounds ; Blood Flow Velocity ; Cochlea ; blood supply ; Free Radicals ; pharmacology ; Guinea Pigs ; Laser-Doppler Flowmetry ; Microcirculation ; drug effects ; Picrates ; pharmacology ; Random Allocation

OBJECTIVETo investigate the effects of atrial natriuretic peptide (ANP) on ischemia and reperfusion cochlea in guinea pigs.

METHODSThe guinea pigs were randomly allocated into four groups: experiment groups (A1 and B1) and control groups (A2 and B2). Cochlear ischemia and reperfusion was induced by thrombus and thrombolysis method. In experiment group A1, ANP was administered 10 min before the ischemic insult. In experiment group B1, ANP was administered at the beginning of reperfusion. In control groups, instead of ANP, normal sodium was injected. The blood flow of cochlea (CoBF) was monitored continuously with laser Doppler flow meter and the threshold of auditory brainstem response (ABR) was measured.

RESULTSBefore the induction of ischemia, the CoBF of experiment group A1 was higher than that of the control group A2. From the reperfusion moment to the end of the experiment, there was no difference between the CoBF of the two groups. In B1 and B2 groups, no difference could be seen between the two groups before the induction of ischemia. After reperfusion, the blood flow of control group B2 recovered to 70% of the base level, while the CoBF of experiment group B1 restored to almost the same level of the beginning. Before ischemia, the ABR threshold of the four groups had no difference. At 30 min of ischemia, the threshold of experiment group Al was lower than that of control group A2. And there was no difference in experiment group B1 and control group B2. At 30 min and 60 min of reperfusion, the threshold of experiment group B1 was significantly lower than that of control group B2. No difference could be seen between experiment group A1 and control group A2.

CONCLUSIONSAdministration of ANP at the beginning of reperfusion protects the cochlea from ischemia and reperfusion injury. The administration can not only increase the CoBF, but lower the ABR threshold.

Animals ; Atrial Natriuretic Factor ; pharmacology ; Cochlea ; blood supply ; drug effects ; physiopathology ; Disease Models, Animal ; Evoked Potentials, Auditory, Brain Stem ; Guinea Pigs ; Reperfusion Injury ; drug therapy ; physiopathology

OBJECTIVETo establish a mice model of aminoglycoside antibiotics (AmAn) induced ototoxicity. Then to investigate the sensitivity of AmAn induced ototoxicity in three mouse strains and effect of kanamycin on the expression of Na-K-2Cl co-transporter-1 (NKCC1) in stria vascularis.

METHODSC57BL/ 6J, CBA/CaJ, NKCC1 +/- mice (each of twenty-four) were randomly divided into four experimental groups A, B, C and D (A kanamycin alone, B kanamycin plus 2, 3-dihydroxybenzoate, C 2, 3-dihydroxybenzoate alone, D control group). Mice were injected with kanamycin or/and 2, 3-dihydroxybenzoate for 14 days. Auditory function was measured by auditory brainstem response (ABR) and morphology of cochlea was observed by succinate dehydrogenase staining. Expression of NKCC1 was detected by immunohistochemistry.

RESULTSMice in group A developed significant ABR threshold shifts (P < 0.01), which were accompanied by out hair cells loss. Mice in group B significantly attenuated ABR threshold shifts with out hair cells loss (P <0.01). The immunostaining of NKCC1 in stria vascularis was attenuated significantly in group A compared with group D (P < 0.01) while the immunostaining in group B was enhanced than which in group A (P < 0.01). CBA/CaJ mice has the highest sensitivity to AmAn in three mouse strains.

CONCLUSIONSAn mouse model of AmAn induced ototoxicity could be established by administration of kanamycin. Kanamycin could inhibit the expression of NKCC1 in stria vascularis. 2, 3-dihydroxybenzoate could attenuate AmAn induced ototoxicity maybe by enhancing the expression of NKCC1. Mice that had the characteristic of presbycusis didn't show additional sensitivity of AmAn induced ototoxicity.

Animals ; Anti-Bacterial Agents ; toxicity ; Blood Vessels ; drug effects ; metabolism ; Cochlea ; blood supply ; drug effects ; metabolism ; Kanamycin ; toxicity ; Mice ; Mice, Inbred C57BL ; Mice, Inbred CBA ; Parabens ; toxicity ; Sodium-Potassium-Chloride Symporters ; metabolism ; Solute Carrier Family 12, Member 2

OBJECTIVE: To explore the influence of carbogen on lateral wall microvascular of cochlear after acute acoustic trauma. METHOD: Forty guinea pigs were divided into 4 groups: group A (noise damage), group B (carbogen inhalation), group C (noise damage + carbogen inhalation), and the control group without any treatment. The diameter of the column of RBCs (RBC column diameter, RBCCD), blood flow velocity (BFV) and blood flow states(BFS) in microvasculature were measured and described under microscope. RESULT: The microvascular in group A demonstrated a blood flow in contrary direction, granuliform flow, and granular slow flow. The erythrocytes aggregated in the microvascular of the cochlea. The RBCCD decreased 12.1% compared with the control group (P < 0.05). The blood flow in group B showed a laminar flow or laminar granular flow, and the RBCCD increased 20.7% compared with the control group. The blood condition in group C was the same as the control group-laminar granular blood flow; the blood flow with contrary direction was less than group A, and the RBCCD was 17.4% lager than that of group A. CONCLUSION Carbogen can dilate the RBCCD and increase the BFV in stria vascular. So carbogen can alleviate the harm from noise.
Animals ; Blood Flow Velocity ; Carbon Dioxide ; administration & dosage ; therapeutic use ; Cochlea ; blood supply ; Erythrocytes ; cytology ; Female ; Guinea Pigs ; Hearing Loss, Noise-Induced ; pathology ; therapy ; Male ; Microcirculation ; Oxygen ; administration & dosage ; therapeutic use