|Budget Amount *help
¥2,800,000 (Direct Cost: ¥2,800,000)
Fiscal Year 1999: ¥600,000 (Direct Cost: ¥600,000)
Fiscal Year 1998: ¥500,000 (Direct Cost: ¥500,000)
Fiscal Year 1997: ¥1,700,000 (Direct Cost: ¥1,700,000)
Bronchopulmonary neuroepithelial bodies (NEBs), composed of inervated clusters of amine-and peptide-containg cells, are widely distributed throughout the airway mucosa of human and animal lungs. Structuary, NEBs resemble chemoreceptors such as corotid bobies, taste buds and are thought to function as hypoxia senstive airway sensors. Using histochemical and histoimmunochemichal thechniques, NEGs have been shown to contain serotonine (5-HT) and peptidelike substances in their cytoplasmic vesicles. Under alveolar hypoxia, NEBs have been shown to release the vesicles to intercellular space. Though the mechanism of oxygen sensing by these cells and the physiological roles of the release of the cytoplasmic vesicles are unkown, we hypothesize that the release of vesicles which contain 5-HT play essential roles in the responses of pulmonary vascular constriction to inhalational hypoxia (hypoxic pulmonary vasoconstriction, HPV). In this study, we used isolated lung perfusion models of rats and
investigated the effects of inhalational anesthetics, sevoflurane and isoflurane, and hypothermia on the responses of NEBs to hypoxia or HPV. We also examined the effects of partial liquid ventilation, a new ventilatory supporting thechnique for the managiment of sever respiratory failure, on HPV in the isolated lung perfusion models.
Both inhalational anesthetics sevoflurane and isoflurane inhibited HPV dose dependently. Inhalational concentration of 4.0% sevoflurane and 3.0% isoflurane completely blocked the response. But the response of pulmonary vessels to hypoxia was recovered at 60 minutes after ceassation of inhalation. The inhibitory effects of the anesthetics on HPV were reversible. HPV was also inhibited by hypothermia. When the temprature of perfusate was below 30 degrees of centigrade, HPV was completely blocked. According to the increase of the temprature of perfusate above 33 degrees of Centigrade, HPV was restored. HPV was not affected by perflubrone associated partial liquid ventilation. Less