The target of genetic influence and participation of endorphin in chemical control of breathing.

为了阐明遗传影响主要作用于外周化学感受器功能还是髓质呼吸中枢功能，我们对健康成年双胞胎进行了戒断试验[9对同卵双胞胎（MZ）和7对异卵双胞胎（DZ）]。此外，我们测量了生理盐水或纳洛酮输注后对高碳酸血症进行性缺氧的通气反应，以研究纳洛酮是否影响健康成人低氧和高碳酸血症共存时的化疗敏感性。代表缺氧刺激和外周<CO_2> - <O_2>相互作用的通气指标是遗传决定的，而代表髓质缺氧抑制和中央<CO_2> - <O_2>相互作用的通气指标主要受环境力的影响。从16对不同的MZ和DZ中随机选择的16名受试者，服用纳洛酮后对高碳酸血症进行性缺氧的通气反应明显高于生理盐水。纳洛酮对高碳酸血症进行性缺氧通气反应变化的对内方差在MZ组明显小于DZ组。这些结果表明，遗传影响主要作用于外周化学感受器功能，内源性阿片样物质参与健康成人呼吸的化学控制。内源性阿片类药物控制呼吸的功能可能涉及基因决定的因素。

To clarify whether genetic influence acts chiefly upon peripheral chemoreceptor function or that of medullary respiratory center, we studied withdrawal test in healthy adult twins [9 pairs of monozygotic twins (MZ) and 7 pairs of dizygotic twins (DZ)]. Further, we measured ventilatory response to hypercapnic progressive hypoxia either after normal saline or naloxone infusion to study whether naloxone affect chemosensitivity in coexistence of hypoxia and hypercapnia in healthy adults. A ventilatory index which represented hypoxic stimulation and peripheral <CO_2> - <O_2> interaction was genetically determined, whereas another index which represented hypoxic medullary depression and central <CO_2> - <O_2> interaction was influenced predominantly by environmental force. The ventilatory response to hypercapnic progressive hypoxia increased significantly after naloxone compared to normal saline in 16 subjects who were selected randomly from 16 different pairs of MZ and DZ. Within-pair variance for the change after naloxone in ventilatory response to hypercapnic progressive hypoxia was significantly smaller in MZ than DZ. These results suggest that genetic influence acts mainly upon peripheral chemoreceptor function and that endogenous opioids participate in chemical control of breathing in healthy adults. The funcion of endogenous opioids in control of breathing may involve genetically determined factors.