Department of Neurology, Mount Sinai School of Medicine, Box 1135 1 East 100th Street, New York, NY 10029, USA.
Exp Brain Res. 2011 Apr;210(1):45-55. doi: 10.1007/s00221-011-2604-4. Epub 2011 Mar 4.
Blood pressure (BP) and heart rate (HR) were studied in isoflurane-anesthetized Long-Evans rats during sinusoidal galvanic vestibular stimulation (sGVS) and sinusoidal oscillation in pitch to characterize vestibular influences on autonomic control of BP and HR. sGVS was delivered binaurally via Ag/AgCl needle electrodes inserted over the mastoids at stimulus frequencies 0.008-0.4 Hz. Two processes affecting BP and HR were induced by sGVS: 1) a transient drop in BP (≈15-20 mmHg) and HR (≈3 beats(-1)), followed by a slow recovery over 1-6 min; and 2) inhibitory modulations in BP (≈4.5 mmHg/g) and HR (≈0.15 beatss(-1)/g) twice in each stimulus cycle. The BP and HR modulations were approximately in-phase with each other and were best evoked by low stimulus frequencies. A wavelet analysis indicated significant energies in BP and HR at scales related to twice and four times the stimulus frequency bands. BP and HR were also modulated by oscillation in pitch at frequencies 0.025-0.5 Hz. Sensitivities at 0.025 Hz were ≈4.5 mmHg/g (BP) and ≈0.17 beat*s(-1)/g (HR) for pitches of 20-90°. The tilt-induced BP and HR modulations were out-of-phase, but the frequencies at which responses were elicited by tilt and sGVS were the same. The results show that the sGVS-induced responses, which likely originate in the otolith organs, can exert a powerful inhibitory effect on both BP and HR at low frequencies. These responses have a striking resemblance to human vasovagal responses. Thus, sGVS-activated rats can potentially serve as a useful experimental model of the vasovagal response in humans.
在异氟烷麻醉的 Long-Evans 大鼠中，研究了正弦电流前庭刺激（sGVS）和正弦俯仰振荡对血压（BP）和心率（HR）的影响，以描述前庭对 BP 和 HR 自主控制的影响。sGVS 通过插入乳突上方的 Ag/AgCl 针电极以 0.008-0.4 Hz 的刺激频率双耳传递。sGVS 引起了两个影响 BP 和 HR 的过程：1）BP（≈15-20mmHg）和 HR（≈3 次/s(-1)）的短暂下降，随后在 1-6 分钟内缓慢恢复；2）BP（≈4.5mmHg/g）和 HR（≈0.15 次/s(-1)/g）在每个刺激周期中两次的抑制调制。BP 和 HR 的调制彼此几乎同相，并且最容易被低刺激频率激发。小波分析表明，BP 和 HR 中的显著能量与刺激频率带的两倍和四倍相关。BP 和 HR 也被 0.025-0.5 Hz 的俯仰振荡调制。在 20-90°的情况下，0.025 Hz 的灵敏度约为 4.5mmHg/g（BP）和 0.17 次/s(-1)/g（HR）。倾斜引起的 BP 和 HR 调制是异相的，但倾斜和 sGVS 引起反应的频率相同。结果表明，sGVS 诱导的反应可能起源于耳石器官，可在低频下对 BP 和 HR 产生强大的抑制作用。这些反应与人的血管迷走反应非常相似。因此，sGVS 激活的大鼠可能成为人类血管迷走反应的有用实验模型。
