成人急性低氧通气压抑中的内啡肽作用

本工作设想,内啡肽参与了成人急性低氧通气压抑机制。受试者均为健康成年男子。6名受试者吸入中度低氧混合气(12.8％O_2)30min;7名吸入重度低氧混合气(10.8％O_2)20min,其中6名并在重度低氧下吸入三口纯氮气。吸入低氧气前先由静脉注入生理盐水(对照)或纳洛酮(中度低氧5mg,重度低氧10mg)。观察低氧时的通气反应、终末潮气二氧化碳分压(P_(ETCO2)、动脉血氧饱和度和外周低氧通气敏感性以及纳洛酮对上述测定的影响。结果表明,纳洛酮使重度低氧下的通气压抑明显减弱,低氧第3～15分钟的通气水平明显高于对照实验;而P_(ETCO2)明显低于对照值。但纳洛酮对中度低氧下的通气压抑无明显作用。此外,纳洛酮显著增强外周低氧敏感性。结果提示,在重度低氧下,内啡肽参与了成人低氧通气压抑机制,并对外周低氧敏感性有抑制作用。

ROLE OF ENDORPHINS IN HYPOXIC VENTILATORY DEPRESSION IN ADULTS

The present study tested the hypothesis that endorphins might be involved in the mec-anisms of acute hypoxia-induced ventilatory depression in normal adults. 6 adults were exposed to moderate hypoxia(F 102= 12. 8%)for 30 minutes and 7 adults to severe hypoxia (F 102 = 10.8%) for 20 minutes respectively. Minute ventilation, end-tidal Pco2 and Sao2 were measured. In addition, the peripheral hypoxic ventilatory sensitiveness was assessed during severe hypoxia in 6 subjects with the 3-breath N2 method. Naloxone (5 mg in moderate hypoxia and 10 mg in severe hypoxia) was administered intravenously 6 minutes before hypoxic exposure. The results showed that after naloxone administration ventilatory depression was attenuated markedly in severe hypoxia, but not in moderate hypoxia as compared with saline control. Furthermore, peripheral hypoxic ventilatory sensitiveness was strengthened by naloxone. These results indicate that during severe hypoxia endorphins are released and play an important role in ventilatory depression in normal adults.