- 著者
-
森満 保
平島 直子
松元 一郎
- 出版者
- JIBI TO RINSHO KAI
- 雑誌
- 耳鼻と臨床 (ISSN:04477227)
- 巻号頁・発行日
- vol.19, no.1, pp.20-30, 1973
In 1971 Morimitsu et al reported on the effects of sodium chloride crystals administered on the round window membrane upon the cochlear microphonics which were recorded from the basal turn of the cochlea of guinea pigs with differential electrodes technique. The amplitude of CM after the administration of NaCl-crystals showed changes in a regular pattern which is composed of an initial overshoot, a primary decrease, a recovery and a secondary decrease. It was considered that the action of NaCl-crystals should be affected by the permeability of the round window membrane, the production and absorption of the inner ear fluids and the vulnerability of the organ of Corti by the biophysical changes of the fluids.<BR>In order to clarify the mechanism ofthese changes of CM and the effects of sympathomimetic and sympathoplegic drugs in the cochlea, the changes of CM modified by NaCl-crystals were observed after the intravenous injection of the following drugs; norepinephrine, isoproterenol, epinephrine, phenoxybenzamine and propranolol. The α-receptor stimulant (norepinephrine) prolonged the initial overshoot and depressed the grade of the primary decrease of CM, but did not influence the grade, of the secondary decrease. The β-receptor stimulant (isoproterenol) depressed the grades of both decreases and therefore the recovery after the primary decrease was complete. The α-receptor blockade (phenoxybenzamine) caused a slight decrease of CM prior to the initial overshoot, and depressed the grades of both decreases. The β-receptor blockade (propranolol) acted to depress the grade of the primary decrease of CM, but did not influence the grade of the secondary decrease. The α-β-receptor stimulant (epinephrine) caused a slight decrease of CM prior to the initial overshoot and influenced so as to depress the both decreases. The action of epinephrine showed a slight resemblance to that of the 13-receptor stimulant. The results obtained showed that the β-receptor stimulant and the α-receptor blockade have a favorable effect on the reactivation of the homeostatic processes govering the labyrinthine fluids and have a effect to minimize the irreversible damage of the organ of Corti occurring after the placement of NaCl-crystals. Considering different actions between α-receptor acting drugs and the β-receptor acting drugs, it is suspected that the sympathetic nerves in the cochlea also consist of the a and β-receptor which act in a sense antagonistic. As the several possible mechanisms of the actions of these drugs, an effect on the permeability of the blood vessels of the cochlea and of the round window membrane besides an effect on the cochlear blood flow was considered. Furthermore, an effect on the sympathetic nerve which was recognized in the basilar