John D. Dingell VA Medical Center, Detroit, MI 48201, USA.
J Appl Physiol (1985). 2011 Jan;110(1):15-28. doi: 10.1152/japplphysiol.00524.2010. Epub 2010 Aug 19.
This study examined whether time of day and repeated exposure to intermittent hypoxia have an impact on the hypoxic ventilatory response (HVR) and ventilatory long-term facilitation (vLTF). Thirteen participants with sleep apnea were exposed to twelve 4-min episodes of isocapnic hypoxia followed by a 30-min recovery period each day for 10 days. On days 1 (initial day) and 10 (final day) participants completed the protocol in the evening (PM); on the remaining days the protocol was completed in the morning (AM). The HVR was increased in the morning compared with evening on the initial (AM 0.83 ± 0.08 vs. PM 0.64 ± 0.11 l·min⁻¹·%SaO₂⁻¹; P ≤ 0.01) and final days (AM 1.0 ± 0.08 vs. PM 0.81 ± 0.09 l·min⁻¹·%SaO₂⁻¹; P ≤ 0.01, where %SaO₂ refers to percent arterial oxygen saturation). Moreover, the magnitude of the HVR was enhanced following daily exposure to intermittent hypoxia in the morning (initial day 0.83 ± 0.08 vs. final day 1.0 ± 0.08 l·min⁻¹·%SaO₂⁻¹; P ≤ 0.03) and evening (initial day 0.64 ± 0.11 vs. final day 0.81 ± 0.09 l·min⁻¹·%SaO₂⁻¹; P ≤ 0.03). vLTF was reduced in the morning compared with the evening on the initial (AM 19.03 ± 0.35 vs. PM 22.30 ± 0.49 l/min; P ≤ 0.001) and final (AM 20.54 ± 0.32 vs. PM 23.11 ± 0.54 l/min; P ≤ 0.01) days. Following daily exposure to intermittent hypoxia, vLTF was enhanced in the morning (initial day 19.03 ± 0.35 vs. final day 20.54 ± 0.32 l/min; P ≤ 0.01). We conclude that the HVR is increased while vLTF is decreased in the morning compared with the evening in individuals with sleep apnea and that the magnitudes of these phenomena are enhanced following daily exposure to intermittent hypoxia.
这项研究旨在探讨一天中的时间和间歇性低氧的重复暴露是否会对低氧通气反应（HVR）和通气长期易化（vLTF）产生影响。13 名患有睡眠呼吸暂停的参与者每天接受 12 次 4 分钟的等二氧化碳缺氧发作，随后进行 30 分钟的恢复期。在第 1 天（初始日）和第 10 天（最后一天），参与者在晚上（PM）完成方案；在其余的日子里，方案在早上（AM）完成。在初始日（AM 0.83 ± 0.08 与 PM 0.64 ± 0.11 l·min⁻¹·%SaO₂⁻¹；P ≤ 0.01）和最后一天（AM 1.0 ± 0.08 与 PM 0.81 ± 0.09 l·min⁻¹·%SaO₂⁻¹；P ≤ 0.01，其中%SaO₂表示动脉血氧饱和度的百分比），HVR 在早上比晚上增加。此外，在早上每日暴露于间歇性低氧后，HVR 的幅度增加（初始日 0.83 ± 0.08 与最后一天 1.0 ± 0.08 l·min⁻¹·%SaO₂⁻¹；P ≤ 0.03）和晚上（初始日 0.64 ± 0.11 与最后一天 0.81 ± 0.09 l·min⁻¹·%SaO₂⁻¹；P ≤ 0.03）。在初始日（AM 19.03 ± 0.35 与 PM 22.30 ± 0.49 l/min；P ≤ 0.001）和最后一天（AM 20.54 ± 0.32 与 PM 23.11 ± 0.54 l/min；P ≤ 0.01），vLTF 在早上比晚上减少。在每日暴露于间歇性低氧后，vLTF 在早上增加（初始日 19.03 ± 0.35 与最后一天 20.54 ± 0.32 l/min；P ≤ 0.01）。我们的结论是，在患有睡眠呼吸暂停的个体中，与晚上相比，HVR 在早上增加，而 vLTF 减少，并且在每日暴露于间歇性低氧后，这些现象的幅度增加。
