Miyawaki T, Pilowsky P, Sun Q J, Minson J, Suzuki S, Arnolda L, Llewellyn-Smith I, Chalmers J
Department of Medicine, Flinders Medical Centre, Bedford Park, Australia.
Am J Physiol. 1995 Apr;268(4 Pt 2):R909-18. doi: 10.1152/ajpregu.1995.268.4.R909.
Barosensitive neurons in the rostral ventrolateral medulla (RVLM) often have a respiratory-related modulation of their activity. However, the extent of the interaction between baroreceptor and respiratory inputs is controversial. The main aim of the present study was to determine the effect of central respiratory drive (CRD) on the barosensitivity of RVLM neurons. Extracellular recordings were obtained from 68 barosensitive neurons in the RVLM of anesthetized, paralyzed, and bilaterally vagotomized Sprague-Dawley rats. Examination of phrenic-triggered histograms revealed five activity patterns among barosensitive neurons: inspiratory depression (type I, n = 20), early inspiratory activation (type II, n = 14), postinspiratory activation (type III, n = 18), expiratory depression (type IV, n = 5) and no modulation (type V, n = 11). In most neurons (types I and III and 56% of type II) inhibition produced by aortic nerve stimulation was greater in inspiration than in expiration. Cardiac-related modulation, as an index of natural phasic baroreceptor activation, was also greater in inspiration than expiration in type III neurons. The results demonstrate that CRD modulates the baroreflex at the level of the RVLM.
延髓头端腹外侧区（RVLM）的压力敏感神经元的活动通常受到与呼吸相关的调制。然而，压力感受器与呼吸输入之间相互作用的程度仍存在争议。本研究的主要目的是确定中枢呼吸驱动（CRD）对RVLM神经元压力感受性的影响。从麻醉、麻痹并双侧迷走神经切断的Sprague-Dawley大鼠的RVLM中68个压力敏感神经元进行细胞外记录。对膈神经触发直方图的检查显示，压力敏感神经元存在五种活动模式：吸气抑制（I型，n = 20）、吸气早期激活（II型，n = 14）、吸气后激活（III型，n = 18）、呼气抑制（IV型，n = 5）和无调制（V型，n = 11）。在大多数神经元（I型和III型以及II型的56%）中，主动脉神经刺激在吸气时产生的抑制作用大于呼气时。作为自然相位性压力感受器激活指标的心脏相关调制，在III型神经元中也是吸气时大于呼气时。结果表明，CRD在RVLM水平调节压力反射。
