Sympathetic Innervation of Human Mesenteric Artery and Vein

Abstract

Background: Innervation of blood vessels shows inter-species variability. There are few studies on the innervation of human vessels; thus, healthy mesenteric vessels were studied to identify the expression of immunomarkers and the morphology of sympathetic innervation as the basis for a study of mesenteric vessels in inflammatory bowel disease. Methods and Results: Electron microscopy studies examined the relationships of nerves to smooth muscle cells. In veins, nerves were distributed throughout the medial smooth muscle coat, often in close apposition (50 nm) to smooth muscle cells. In arteries, nerves were located at the adventitial-medial border, few closer than 2,000 nm to smooth muscle cells, often with interposing connective tissue and Schwann cell processes. There was a significantly greater nerve density in veins than in arteries (227 vs. 41 mm²; p = 0.03). Immunohistochemical studies revealed the presence of sympathetic and sensory-motor nerves in arteries and veins. Conclusions: It is suggested that in humans with an upright stance, the mesenteric venous system plays a particularly important role in controlling mesenteric capacitance, which is reflected by their dense innervation. It is speculated that transmitters released from perivascular nerves supplying the human mesenteric arteries may play a long-term (trophic) role in addition to short-term signalling roles.

Evidence for unmyelinated C fibres and inflammatory cells in human varicose saphenous vein

“…In contrast, in dental pulp vasculature, the density of vasomotor adrenergic innervation received by venules is four times lower than that received by arterioles (16). C fibre bundles or clusters, which are often located close to the vasa vasorum and adventitia (15,17,18), were also observed in some of our specimens.…”

“…Nerve fibre density is related to vessel territories concerned with organ functions. In Number of samples* with C fibres human mesenteric veins, the density of sympathetic nerve fibres is roughly sixfold higher than in arteries (15), and they appear as unmyelinated fibres. Their higher density may reflect the need for fine control of vascular tone for mesenteric capacitance control because of their thick muscular media.…”

Physiologic Changes in the Heart Following Cessation of Mechanical Ventilation in a Porcine Model of Donation After Circulatory Death: Implications for Cardiac Transplantation

“…The majority of the total blood volume is contained within the venous capacitance system (23). A high density of a-adrenergic receptors distributed throughout the media of this system makes it highly sensitive to stimulation by the sympathetic nervous system, which would cause a decrease in venous capacitance and an increase in RV preload (23)(24)(25). However, the degree to which an increase in venous return can augment LV preload and systemic cardiac output in the DCD context may be limited by the presence of persistently elevated pulmonary vascular resistance.…”

Impaired Function of Prejunctional Adenosine A1 Receptors Expressed by Perivascular Sympathetic Nerves in DOCA-Salt Hypertensive Rats

“…This issue is important in mesenteric arteries (MAs) and veins (MVs), because they are densely innervated by sympathetic nerves (King et al, 2007). Sympathetic nerves supply blood vessels at the adventitial-medial border in arteries, and they distribute more deeply into the media for veins (Birch et al, 2008). This differential anatomic arrangement suggests that prejunctional regulation of transmitter release may also differ in arteries and veins.…”