CENTRAL CARDIOVASCULAR CONTROL DURING BLOOD LOSS

彻底了解创伤性失血的生理后果对于有效地医疗管理该问题及其相关并发症至关重要。有意识的动物（包括人类）对失血的反应是双相的。该模式的特点是最初的交感神经兴奋和动脉血压的维持与体液系统的激活很少。随后出现交感神经抑制、血管舒张、低血压和加压素、肾上腺素和肾素释放增加。关于控制低血压发作的中枢神经系统网络，实际上知之甚少。中脑导水管周围灰质（PAG）是一个脑区，可能是重要的控制心血管和神经体液反应失血。我们的一般假设是，腹外侧PAG在对出血和应激性感觉刺激的综合血流动力学和神经体液反应的中央控制中非常重要。我们将使用一种方法的组合来评估清醒家兔急性脑出血时腹外侧PAG参与心血管控制的情况。这种方法的组合使用是新颖的，这将是第一个研究，以解决正在进行的中央心血管控制机制在生理事件，如出血。本研究的具体目的是：1）明确清醒家兔腹外侧PAG在失血和应激时血流动力学反应中的作用。2)目的：定量观察清醒家兔出血和应激时PAG腹外侧区神经元的反应。3)了解清醒家兔失血时腹外侧PAG中肾上腺素能和阿片能机制的作用。

A thorough understanding of the physiological consequences of traumatic blood loss is essential to effective medical management of the problem and the associated complications. The response to blood loss in conscious animals (including humans) is biphasic. The pattern is characterized initially by sympathoexcitation and arterial blood pressure maintenance with little activation of humoral systems. This is followed later by sympathoinhibition, vasodilation, hypotension, and increased release of vasopressin, epinephrine and renin. Very little is actually known about the central nervous system networks controlling the onset of hypotension. The periaqueductal gray (PAG) is a brain area that may be important in the control of the cardiovascular and neurohumoral response to blood loss. Our general hypothesis is that the ventrolateral PAG is important in the central control of the integrated hemodynamic and neurohumoral response to hemorrhage and stressful sensory stimuli. We will use a combination of approaches to evaluate ventrolateral PAG involvement in cardiovascular control during acute hypotensive hemorrhage in conscious rabbits. The use of this combination of approaches is novel, and this will be one of the first studies to address ongoing central cardiovascular control mechanisms during a physiological event such as hemorrhage. The Specific Aims of this study are: 1) To define the role of the ventrolateral PAG in the hemodynamic response to blood loss and stress in the conscious rabbit. 2) To quantify the response of ventrolateral PAG neurons during hemorrhage and stress in the conscious rabbit. 3) To understand the role of serotonergic and opioidergic mechanisms in the ventrolateral PAG during blood loss in the conscious rabbit.