Musculo-respiratory interactions on orthostatic cardiovascular and autonomic responses

2018 Fiscal Year Final Research Report

• Project/Area Number: 16K07540
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Research Field: Applied anthropology
• Research Institution: Yamagata University
• Principal Investigator: Niizeki Kyuichi 山形大学, 大学院理工学研究科, 教授 (00228123)
• Project Period (FY): 2016-04-01 – 2019-03-31
• Keywords: 起立 / 心拍出量 / 血管抵抗 / 位相同期

Outline of Final Research Achievements

The purpose of the present study was to determine whether phase coupling occurs between heartbeats and rhythmic lower-leg cuff inflation (RCI) which mimics muscle pump function, and to investigate the effect of the timing of muscle pump with respect to respiration on orthostatic cardiovascular autonomic responses. A periodic phase coupling occurred between heartbeats and RCI during quiet standing (QS). The RCI led to increase in stroke volume (SV) and lengthening of R-R intervals (RRI), however, these were not related with the strength of phase coupling. Reduction in SV and an increase in total peripheral resistance observed in QS were suppressed by repetitive heel up (HUP) maneuver. When HUP was initiated at expiration, blood pressure (BP) was increased and when initiated at inspiration, respiratory modulation in RRI was increased. These results indicate that orthostatic cardiovascular and autonomic responses are influenced by the timing of muscle pump with respect to respiration.

Free Research Field

生体生理工学

Academic Significance and Societal Importance of the Research Achievements

筋ポンプ作用は静脈還流量を増し，起立時の心拍出量維持に寄与している。しかし，その機能が呼吸ポンプ作用によってどのように修飾されるのか生理学的実証はなされていない。本研究は，起立時に筋ポンプ動作(踵上げ運動)を吸気開始に行う場合と呼気開始に行う場合で循環系指標の挙動を解析した。呼気時の筋ポンプ動作は血圧を上昇させ，心拍と血圧の呼吸性変動を減弱させるが，吸気時の筋ポンプ動作は逆に呼吸性変動を増大させ，心拍間隔を延長させた。吸気のタイミングで行う筋ポンプ動作は迷走神経活動を亢進させることが示唆され，起立不耐性を示す患者に有効な対処療法となり得ると考えられた。