Taboni Anna, Fagoni Nazzareno, Fontolliet Timothée, Moia Christian, Vinetti Giovanni, Ferretti Guido
Department of Anaesthesiology, Pharmacology, Intensive Care, and Emergencies, University of Geneva, Geneva, Switzerland.
Department of Molecular and Translational Medicine, University of Brescia, Brescia, Italy.
Am J Physiol Regul Integr Comp Physiol. 2021 Dec 1;321(6):R960-R968. doi: 10.1152/ajpregu.00167.2021. Epub 2021 Oct 13.
We hypothesized that during rapid uptilting at rest, due to vagal withdrawal, arterial baroreflex sensitivity (BRS) may decrease promptly and precede the operating point (OP) resetting, whereas different kinetics are expected during exercise steady state, due to lower vagal activity than at rest. To test this, eleven subjects were rapidly (<2 s) tilted from supine (S) to upright (U) and vice versa every 3 min, at rest and during steady-state 50 W pedaling. Mean arterial pressure (MAP) was measured by finger cuff (Portapres) and R-to-R interval (RRi) by electrocardiography. BRS was computed with the sequence method both during steady and unsteady states. At rest, BRS was 35.1 ms·mmHg (SD = 17.1) in S and 16.7 ms·mmHg (SD = 6.4) in U ( < 0.01), RRi was 901 ms (SD = 118) in S and 749 ms (SD = 98) in U ( < 0.01), and MAP was 76 mmHg (SD = 11) in S and 83 mmHg (SD = 8) in U ( < 0.01). During uptilt, BRS decreased promptly [first BRS sequence was 19.7 ms·mmHg (SD = 5.0)] and was followed by an OP resetting (MAP increase without changes in RRi). At exercise, BRS and OP did not differ between supine and upright positions [BRS was 7.7 ms·mmHg (SD = 3.0) and 7.7 ms·mmHg (SD = 3.5), MAP was 85 mmHg (SD = 13) and 88 mmHg (SD = 10), and RRi was 622 ms (SD = 61) and 600 ms (SD = 70), respectively]. The results support the tested hypothesis. The prompt BRS decrease during uptilt at rest may be ascribed to a vagal withdrawal, similarly to what occurs at exercise onset. The OP resetting may be due to a slower control mechanism, possibly an increase in sympathetic activity.
我们假设，在静息状态下快速上身倾斜时，由于迷走神经张力减退，动脉压力感受器反射敏感性（BRS）可能会迅速下降，并先于工作点（OP）重置，而在运动稳态期间，由于迷走神经活动低于静息状态，预计会出现不同的动力学变化。为了验证这一点，11名受试者在静息状态和50W踏板运动稳态期间，每3分钟从仰卧位（S）快速（<2秒）倾斜至直立位（U），然后再返回仰卧位。通过指套式血压计（Portapres）测量平均动脉压（MAP），通过心电图测量R-R间期（RRi）。在稳态和非稳态期间均采用序列法计算BRS。静息时，仰卧位的BRS为35.1ms·mmHg（标准差=17.1），直立位为16.7ms·mmHg（标准差=6.4）（P<0.01）；仰卧位的RRi为901ms（标准差=118），直立位为749ms（标准差=98）（P<0.01）；仰卧位的MAP为76mmHg（标准差=11），直立位为83mmHg（标准差=8）（P<0.01）。在倾斜过程中，BRS迅速下降[首个BRS序列为19.7ms·mmHg（标准差=5.0）]，随后是OP重置（MAP升高而RRi无变化）。运动时，仰卧位和直立位的BRS和OP无差异[BRS分别为7.7ms·mmHg（标准差=3.0）和7.7ms·mmHg（标准差=3.5），MAP分别为85mmHg（标准差=13）和88mmHg（标准差=10），RRi分别为622ms（标准差=61）和600ms（标准差=70）]。结果支持了所验证的假设。静息时倾斜过程中BRS的迅速下降可能归因于迷走神经张力减退，类似于运动开始时的情况。OP重置可能是由于控制机制较慢，可能是交感神经活动增加所致。
