Sympathetic effects on spontaneous activity in bovine mesenteric lymphatics

Area of Science:

• Physiology
• Autonomic Nervous System
• Lymphatic System

Background:

• The autonomic nervous system plays a crucial role in regulating vascular function.
• Understanding the neural control of lymphatic vessels is essential for lymphatic system physiology.

Purpose of the Study:

• To investigate the influence of autonomic nerves on the spontaneous activity of isolated bovine mesenteric lymphatics.
• To differentiate the responses of valvular and intervalvular segments to neural stimulation.

Main Methods:

• Isolated bovine mesenteric lymphatic segments were subjected to transmural electrical stimulation.
• Responses were analyzed under the influence of various drugs, including tetrodotoxin, guanethidine, cocaine, hexamethonium, atropine, propranolol, and phentolamine.

Main Results:

• Transmural stimulation caused distinct effects: inhibition in valvular segments and acceleration in intervalvular segments.
• Norepinephrine release from sympathetic nerve terminals was implicated, with beta-adrenoceptors predominant in valvular regions.
• Specific drug effects elucidated the roles of different neurotransmitters and receptors.

Conclusions:

• Autonomic neural activity differentially modulates lymphatic vessel contractions.
• Norepinephrine and beta-adrenoceptors are key mediators in the valvular lymphatic segments.
• The findings provide insights into the neuro-regulation of lymphatic pumping.