Some embryological aspects of cholinergic innervation in the cardiovascular system--a close association with the subintestinal circulatory channel.

A series of our studies on the dog venous system revealed that cholinergic excitatory innervation was localized in a group of veins: the portal, mesenteric, and hepatic veins and the middle segment of the inferior vena cava. Our studies on pharmacological responsiveness of dog veins also revealed that they could be divided into two groups: the visceral and somatic parts, and the cholinergic excitatory innervation localized to the visceral part. Considering these results and some relevant literature, a hypothesis is proposed on the classification of muscles of the cardiovascular system and some embryological aspects of the parasympathetic cholinergic innervation in the circulatory system are discussed.

Neuropeptide Y enhances permeability across a rat aortic endothelial cell monolayer.

Previously, in vivo studies showed that neuropeptide Y (NPY) elevates vascular permeability in isolated lung perfusion preparations, possibly through binding to the NPY Y(3) receptor. The present study used monolayers in a double-chamber culture method under conditions of normoxia (5% CO(2)-20% O(2)-75% N(2)) or hypoxia (5% CO(2)-5% O(2)-90% N(2)) to test the hypothesis that NPY directly affects rat aortic endothelial cells (RAECs). RAECs were cultured on the base of the upper chamber, into which FITC-labeled albumin was introduced, and permeation into the lower chamber was measured.

Absence of endothelium in invertebrate blood vessels: significance of endothelium and sympathetic nerve/medial smooth muscle in the vertebrate vascular system.

In the course of evolution, two remarkable changes seem to have occurred in vertebrate circulation: the appearance and development of the "endothelium or endothelial tubular system" and "sympathetic nerve/medial smooth muscle system". In the present article, some relevant literature is reviewed and discussed. Absence of endothelium in the vascular wall of most invertebrates had been known and was confirmed by recent electron microscopic studies.

Evidence for the excitatory cholinergic innervation in the rabbit portal vein.

We examined the possible existence of excitatory cholinergic innervation in isolated rabbit portal vein. Longitudinal strips of the vein in the presence of both phenoxybenzamine, an alpha-adrenoceptor antagonist, and NG-nitro-L-arginine, an inhibitor of nitric oxide synthase, exhibited a small contraction in response to transmural electrical stimulation (ES). The contractile response to ES was augmented by physostigmine, an anticholinesterase agent, and inhibited by atropine.