Differential sympathetic reflex control in excerise

描述（由申请人提供）：运动升压反射被广泛认为在人类和动物运动期间控制交感神经流出至血管系统中起重要作用。 这种反射被认为是由骨骼肌收缩引起的，由两种类型的刺激引起，即机械刺激和代谢刺激。 运动加压反射弧的感觉臂由III和IV类纤维组成，它们一起被称为细纤维肌传入。 第I和第II类纤维不参与引起这种反射。 虽然运动加压反射在运动中增加动脉血压的作用已经得到了很好的证实，但它对交感神经流出到特定内脏和躯体结构的控制仍有争议。 对于代谢受体在反射性激活交感神经流出到皮肤脉管系统中所起的作用，情况尤其如此。 此外，细纤维机械感受器和代谢感受器在激活交感神经流出到骨骼肌和肾脏中所起的具体作用尚不清楚。 本申请中提出的实验将确定阻断来自细纤维肌肉机械感受器和代谢感受器的收缩诱导的输入对支配后肢有毛皮肤的脉管系统、后肢骨骼肌的脉管系统和肾脏的单纤维交感节后传出纤维的反应的影响。 通过腘动脉注射钆（一种阻断机械通道的药物），可阻止去脑未麻醉猫小腿三头肌产生的机械感受器输入。 这些肌肉的代谢受体输入将被腘动脉注射PPADS（一种嘌呤能2受体拮抗剂）阻断。 传出放电的交感神经性质将通过以下方式识别：1.）表明传出神经被施加到胸或腰交感神经链的电脉冲激活; 2.）表明自发和诱发的活动都被用六甲铵的神经节阻滞所阻止;和3.）这表明肾、肌肉以及在较小程度上皮肤交感神经放电的活动受动脉压力感受器的控制。 这些实验为研究细纤维肌肉机械感受器和代谢感受器在运动中控制交感神经流出中的作用提供了新的信息。

DESCRIPTION (provided by applicant): The exercise pressor reflex is widely believed to play an important rote in controlling the sympathetic outflow to the vasculature during exercise in both humans and animals. The reflex is believed to arise from contracting skeletal muscles and is evoked by two types of stimuli, namely mechanical and metabolic. The sensory arm of the exercise pressor reflex arc is comprised of group III and IV fibers, which together haw been termed thin fiber muscle afferents.. Group I and II fibers do not participate in evoking this reflex. Although the role played the exercise pressor reflex in increasing arterial blood pressure during exercis, is well established, its control of the sympathetic outflow to specific visceral and somatic structures controversial. This is especially the case for the role played by metaboreceptors in reflexly activating the sympathetic outflow to the vasculature of the skin. In addition, the specific roles played by thin fiber mechanoreceptors and metaboreceptors in activating the sympathetic outflow to the skeletal muscles and the kidney are unknown. The experiments proposed in this application will determine the effect of blocking the contractioninduced input from thin fiber muscle mechanoreceptors and metaboreceptors on the responses of single fiber sympathetic postganglionic efferent fibers innervating the vasculature of hind limb hairy skin, the vasculature of hind limb skeletal muscle and the kidney. Mechanoreceptor input arising from the triceps surae muscles of decerebrate unanesthetized cats will be prevented by popliteal arterial injections of gadolinium, an agent which blocks mechanogated channels. Metaboreceptor input from these muscles will be blocked by popliteal arterial injections of PPADS, a purinergic 2 receptor antagonist. The sympathetic nature of the efferent discharge will be identified by: 1.) showing that the efferents are activated by an electrical pulse applied to the thoracic or lumbar sympathetic chain; 2.) showing that both spontaneous and evoked activity is prevented by ganglionic blockade with hexamethonium; and 3.) showing that the activity of the renal, muscle and to a lesser extent, skin sympathetic discharge is under control of the arterial baroreceptors. The proposed experiments will provide new information about the role played by thin fiber muscle mechanoreceptors and metaboreceptors in controlling the sympathetic outflow during exercise.