Spinal anesthesia blocks the sympathetic efferent nerves that release norepinephrine onto vascular smooth muscle, the SA node, the AV node, the conduction system and the muscle cells of the heart.

• 脊髓麻醉阻滞交感传出神经释放去甲肾上腺素到血管平滑肌、窦房结、房室节、传导系统和心肌细胞。