Sympathetic fibers

Sympathetic fibers are the efferent axons of the sympathetic nervous system (SNS) that originate in the spinal cord and extend to various organs, glands, and blood vessels throughout the body. They primarily utilize norepinephrine as a neurotransmitter to mediate the 'fight-or-flight' response, increasing heart rate, inducing vasoconstriction, and mobilizing energy stores. While not a single molecular target, these fibers are the focus of therapeutic intervention in conditions characterized by sympathetic overactivity, such as resistant hypertension and chronic heart failure. Interventions include sympatholytic drugs that interfere with neurotransmission and procedural approaches like renal denervation, which targets the sympathetic nerves surrounding the renal arteries to lower systemic blood pressure. Because they are anatomical structures rather than specific proteins, they do not fit the traditional definition of a molecular drug target but remain a critical focal point for neuromodulation and cardiovascular pharmacology.

Other names

Sympathetic nervesAdrenergic fibersSympathetic nervous system fibersEfferent sympathetic pathways

Pharmacological agents typically modulate sympathetic fibers by inhibiting the release of norepinephrine, depleting neurotransmitter stores, or acting as false transmitters to reduce sympathetic outflow. Non-pharmacological approaches include surgical sympathectomy or catheter-based radiofrequency ablation (e.g., renal denervation) to physically disrupt the nerve fibers and reduce overactive signaling.