Adrenergic innervation of the nasal mucosa in cat. A histological and physiological study.
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Biomedical subjects
O Densert
Publications and source records attributed to O Densert.
Synaptic vesicles in the cochlea.
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Adrenergic innervation in the rabbit cochlea.
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Immediate restoration of basal sensorineural hearing (Mb Meniere) using a pressure chamber.
A new technique for the restoration of basal sensorineural hearing loss in Mb Meniere was described. Three cases with unilateral basal sensorineural hearing loss, fullness of the ear, and tinnitus were reported. In the acute stage of their disease the patients were treated in a pressure chamber where it was possible to increase or decrease the air pressure within the range +/- 110 cm H2O. The equilibration of middle ear pressures to surrounding air pressures was checked. Exposure to underpressure resulted in a rise of the hearing thresholds at low frequencies and relief of subjective symptoms. When the air pressure was increased the hearing thresholds were lowered and the sensation of tinnitus and fullness of the ear was accentuated. Changes in air pressure did not affect the healthy ears or the high frequencies in the diseased ear. Hearing improvement attained at exposure to underpressure seemed to remain at atmospheric pressure level. The investigation was performed on the hypothesis that a distended membranous labyrinth might cause a venous congestion of the vestibular aqueduct, resulting in impaired endolymph absorption in the endolymphatic sac. Possible effects of changes in environmental air pressure on the inner ear were discussed.
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A fluorescence and electron microscopic study of the adrenergic innervation in the vestibular ganglion and sensory areas.
The adrenergic innervation in the vestibular ganglion and sensory areas in rabbit and cat was studied with fluorescence and electron microscopic techniques. All adrenergic nerve fibres consisted of postganglionic axons from the ipsilateral superior cervical ganglion. In rabbit, postganglionic nerve fibres passed via the carotic plexus. Probably because of the anatomical difference, the feline internal carotic artery being rudimentary, all sympathetic nerve fibres to the inner ear in cat passed via the tympanic plexus. In the vestibular ganglion there was a uniform distribution of adrenergic nerve fibres and there was no difference in distribution patterns between rabbit and cat. There was a continuous blood vessel innervation and an innervation independent of blood vessles. The adrenergic innervation extended to the sensory areas but did not seem to penetrate the basement membrane and no adrenergic nerve terminals were found in direct contact with sensory or secretory cells.
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The effect of 6-hydroxydopamine on the rabbit cochlea.
6-OH-DA is an isomer of noradrenalin which is selectively taken up by adrenergic axons. Noradrenalin stores are displaced by 6-OH-DA and at a certain intraneuronal concentration, degeneration of the terminals occurs and results in a chemical sympathectomy. The effects of 6-OH-DA on the rabbit cochlea were studied with fluorescence and electron microscopy after systemic administration of the substance and after local perfusion of the cochlea. Doses of 25 to 200 mg/kg were used. After intravenous injection there was an initial accumulation of 6-OH-DA in noradrenalin storage vesicles. A dose of 50 mg/kg 6-OH-DA initiated marked signs of degeneration in adrenergic nerve terminals but did not cause breakdown of their cell membranes. Higher doses did not seem to increase the damage. Local perfusion with 6-OH-DA gave rise to extensive degeneration of adrenergic nerve terminals and after 7 days all terminals had disappeared. These findings indicate the presence of a blood-perilymph barrier to 6-OH-DA. Some degeneration was also evident in cholinergic axons of the inner spiral bundle and of the tunnel spiral bundle.
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The influence of perilymphatic pressure on the displacement of the tympanic membrane. A quantitative study on human temporal bones.
A model study on human temporal bones was performed. A microflow method was used in order to assess the possibility of making indirect recordings of changes in the inner ear pressures. Changes in the perilymphatic pressure were recorded as displacements of the tympanic membrane, the stapedius reflex being artificially elicited by forces applied briefly to the stapedius tendon. Changes in the perilymphatic pressures in the range of +/-15 cm H2O affected the position of the tympanic membrane and the "stapedius reflex response". The microflow method used seems suitable for the clinical recording of changes in the intralabyrinthine pressure.
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Occurrence and distribution of VIP nerves in the nasal mucosa and tracheobronchial wall.
Nerves displaying vasoactive intestinal peptide (VIP) immunoreactivity were detected in the upper respiratory tract of guinea pigs, rabbits and cats. VIP nerves were numerous in the cat, less numerous in the rabbit and rare in the guinea pig. In the nasal mucosa, fine varicose VIP nerves were found to surround nasal glands and small blood vessels. In the tracheobronchial wall VIP nerves were observed around seromucous glands, blood vessels and smooth muscle. Ganglia located in the walls of the trachea and main bronchi contained clusters of VIP immunoreactive nerve cell bodies, conceivably representing the origin of the VIP fibres found in this region.
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Perilymphatic pressure in the cat. Description of a new method for study of inner ear hydrodynamics.
Continuous recordings of the perilymphatic (Pp), cerebrospinal fluid (PCSF), central venous (PCV) and arterial (PA) pressures have been performed on anesthetized cats. The perilymphatic space was reached by an extraural approach that leaves the ear canal and middle ear intact. A conical canal was drilled into the temporal bone down to the vestibule. The position of the canal was later confirmed histologically. A small, threaded, metallic cannula was screwed into the bone. For pressure measurements Millar microtip transducers were used, thus giving minimum measurement volume displacement. The mean PP and PCSF were found to be equal, whereas the maximum pressure during expiration was significantly higher in the CSF. not affected by the given anesthetics. Ligation of the external jugular veins had a minor and temporary effect on the PP and PCSF. The method is considered to be suitable for studies on the inner ear hydrodynamics as well as for audiophysiological measurements with an intact middle ear transmission system.
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Transmission of square wave pressure pulses through the perilymphatic fluid in cats.
The inner ear hydrodynamics have been studied in a series of experiments on cats. A detailed analysis has been made of the perilymphatic pressure response to square wave pressure pulses applied to the ear canal and middle ear. It was found that the initial pressure response was followed by a rebound pressure response of the opposite phase. It was also found that in most cases each phase of the pressure response could be expressed in terms of two time constants. When the cochlear aqueduct was patent, the perilymphatic pressure response showed almost equal positive and negative pressure changes. However, when the cochlear aqueduct was surgically blocked, the perilymphatic pressure response consisted almost exclusively of the first phase of the response, while the rebound phase disappeared almost completely. The possibility of influencing the inner ear fluid balance in Meniere's disease by external pressure changes is discussed in the light of the present experimental results.
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Transmission of complex pressure waves through the perilymphatic fluid in cats.
The response of the perilymphatic fluid to complex pressure waves, composed of low-frequency sine waves superimposed on square-wave pressure pulses of varying amplitude was studied. In cats with a patent cochlear aqueduct a pronounced positive pressure change could be induced in the perilymphatic fluid when complex pressure waves were used. The time constants associated with the stabilization of the perilymphatic pressure after the application of pressure complexes were longer than those associated with square-wave pulses alone. The results indicate that the functional patency of the cochlear aqueduct could be influenced by the transmission of complex pressure waves. The results also indicate that when trying to influence the inner ear hydrodynamic balance in patients with Meniere's disease, the effect of complex pressure waves is far superior to the effect of square-wave pressure pulses in patients with an open cochlear aqueduct.
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