| Project/Area Number |
63870033
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| Research Category |
Grant-in-Aid for Developmental Scientific Research
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| Allocation Type | Single-year Grants |
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| Research Field |
Respiratory organ internal medicine
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| Research Institution | Showa University |
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Principal Investigator |
HOMMA Ikuo Showa Univ., Dept. of Physiology, Professor, 医学部, 教授 (20057079)
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| Co-Investigator(Kenkyū-buntansha) |
IIKURA Yoji National Children's Hospital, Dept. of Pediatrics, Chief Doctor, 小児科, 医長
ISOBE Akiyo Showa Univ., Dept. of Physiology, Research Associate, 医学部, 助手 (60176261)
SIBUYA Masato Showa Univ., Dept. of Physiology, Research Associate, 医学部, 助手 (80187418)
IWASE Michiko Showa Univ., Dept. of Physiology, Research Associate, 医学部, 助手 (80119164)
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| Project Period (FY) |
1988 – 1989
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| Project Status |
Completed (Fiscal Year 1989)
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| Budget Amount *help |
¥3,400,000 (Direct Cost: ¥3,400,000)
Fiscal Year 1989: ¥1,700,000 (Direct Cost: ¥1,700,000)
Fiscal Year 1988: ¥1,700,000 (Direct Cost: ¥1,700,000)
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| Keywords | Irritant receptor / Pulmonary stretch receptor / High frequency inflation / Inhalation / Asthma / Alternaria / ネブライザ- / 迷走神経 / イリタント受容器 / 高頻度刺激 / 喘息 |
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| Research Abstract |
Development of the high-frequency nebulizer
Inhalation is a widely used therapy for asthma. The purpose is to deliver bronchodilating agents to the airway, where two major types of mechanoreceptors, irritant receptors (IR) and pulmonary stretch receptors (PSR), are known to exist. The reflexes induced by IR afferents and PSR afferents have reciprocal effects. For example, IR afferents contract the airway smooth muscles, but PSR afferents inhibit the contraction. The aim of this work was to develop a nebulizer that would not only deliver bronchodilating agents to the airway, but also stimulate PSR.
First, the characteristics of PSR and IR were examined in rabbits. Airway application of positive pressure pulses at high-frequency, as designated high- frequency inflation (HFI), was found to stimulate both types of receptors. HFI below 20 Hz induced effects similar to IR activation. On the other hand, HFI above 30 Hz induced effects similar to PSR activation. Between 20 Hz and 30 Hz, the two reflex responses to HFI canceled each other. The frequency at which reflex responses were canceled was designated as the central index.
In Alternaria-sensitized rabbits, the reflex sensitivity to the afferent inputs from the IR was more apparent and the central index was shifted to higher frequencies. Therefore it seems necessary to use HFI over 50 Hz to induce reflex response by PSR activation in asthmatic patients. A new nebulizer was thus designed to produce 100 Hz HFI and was called the high-frequency nebulizer. This was shown to be more effective in dilating the airway in the patients than a conventional nebulizer. It seems worthwhile to develop and improve the high-frequency nebulizer for patient use.
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