Effects of Endolymphatic Pressure on Cochlear Function

Research Project

Project/Area Number	60570815
Research Category	Grant-in-Aid for General Scientific Research (C)
Allocation Type	Single-year Grants
Research Field	Otorhinolaryngology
Research Institution	Miyazaki Medical College
Principal Investigator	IDE Minoru Miyazaki Medical College, 医学部, 助手 (00128365)
Co-Investigator(Kenkyū-buntansha)	TETSUY Tono Miyazaki Medical College, 医学部, 助手 (80145424) MIYANAGA Satoshi Miyazaki Medical College, 医学部, 助手 (60200193) FUKIYAMA Mikiko Miyazaki Medical College, 医学部, 教授 (60170114) MORIMITSU Tamotsu Miyazaki Medical College, 医学部, 教授 (40038675) 安達裕一郎宮崎医科大学, 医学部, 助手 (70167922) 牧野浩二宮崎医科大学, 医学部, 助手 (00145434)
Project Period (FY)	1985 – 1987
Project Status	Completed (Fiscal Year 1987)
Budget Amount *help	¥1,800,000 (Direct Cost: ¥1,800,000) Fiscal Year 1987: ¥400,000 (Direct Cost: ¥400,000) Fiscal Year 1986: ¥400,000 (Direct Cost: ¥400,000) Fiscal Year 1985: ¥1,000,000 (Direct Cost: ¥1,000,000)
Keywords	Endolympatic Pressure / Endocochlear DC Potential / マイクロプレッシャーシステム / 血圧
Research Abstract	It is considered that endolymphatic hypertension in Meniere's disease caused hearing loss, but this mechanism is unknown. The purpose of this experimental study is to know how alteration of endolymphatic pressure influences cochlear function. Healthy albino guinea pigs were used for all experiments. The changes of endolymphatic pressure and endocochlear DC potenital by several conditions were recorded with a servo-controlled micro-pressure system. 1)When the perilymphatic space was pressurized, the endolymphatic pressure resulted in as almost same value as the perilymphatic pressure. 2)The placement of NaCl-crystals on the round window membrane that the endolymphatic pressure was gradually decreased within 10 or 15 minutes and was gradually recovered to the initial value, and endocochlear DC poltential was gradually decreased and then became stable. 3)In intravenous injection of isosorbide, the endolymphatic pressure showed a intermittent increase, and then showed gradual decrease, and then gradually recovered to the initial value. The maximum reduction of its pressure was recorded at about 10 minutes after the intravenous injection. While, the endocochlear DC potential showed no significant changes after the intravenous injection of isosorbide. 4)Intravenous injection of glycerol showed the results as same as the injection of isosorbide. The maximum reduction of its pressure was recorded at about 30 minutes after the injection. 5)The endolymphatic pressure showed no significant change during sound exposure. 6)The endolymphatic pressure and the endocochlear DC potential showed almost normal values after about 30 days from sound exposure. Form these results, it is recognized that there are some relations between endolymphatic pressure and cochlear function.