Extrinsic innervation of the canine abdominal vena cava and the origin of cholinergic vasoconstrictor nerves

Abstract

SUMMARY1. The effects ofelectrical stimulation ofthe greater splanchnic nerve and the vagus nerve on the middle segment of the inferior vena cava (i.v.c.) were studied in anaesthetized and unilaterally or bilaterally adrenalectomized dogs. The vascular response of the segment was measured as the change in pressure of an intravascular cuff inserted into the lumen of the segment.2. Electrical stimulation of the greater splanchnic nerve of either side caused an increase in the tension ofthe vein with a delay of less than 3 sec. The tension increased with frequency of stimulation until it reached a maximum at the frequency of 32 Hz. The maximum tension development was consistently larger, by a factor of about two, when the right greater splanchnic nerve was stimulated than when the left was. It seems that the right greater splanchnic nerve supplies more sympathetic nerve fibres to the middle segment of the i.v.c. than does the left.3. The response to electrical stimulation ofthe right or left greater splanchnic nerve was markedly reduced by phentolamine or hexamethonium. The response remaining after treatment with phentolamine or hexamethonium was augmented by neostigmine and diminished by atropine.4. The electrical stimulation of the vagus nerve elicited no response of the vein before and after treatment with neostigmine.5. The effects of electrical stimulation of the right greater splanchnic nerve were further confirmed by a preparation in which the middle segment of the i.v.c. was perfused with Krebs solution in situ. The relation between the frequency of stimulation and the magnitude of the response was almost the same as in the in vivo experiments.6. It was also confirmed in the perfused preparation that the response to electrical stimulation of the right greater splanchnic nerve was reduced by phentolamine and the remaining response was augmented by neostigmine and abolished by atropine.7. Our data show that the middle segment of the canine i.v.c. receives both adrenergic and cholinergic excitatory innervation, preferentially via the right greater splanchnic nerve.Experiments were performed at Nagoya and Sapporo. Authors' names are in alphabetical order. t To whom all correspondence should be addressed.

Absence of Endothelium in Invertebrate Blood Vessels: Significance of Endothelium and Sympathetic Nerve/Medial Smooth Muscle in the Vertebrate Vascular System

“…This may account for the fact that the sympathetic nerves distribute widely to the whole vascular system, while the parasympathetic nerves distribute only to limited sites in the vertebrate vascular system. This view is consistent with our earlier observations of the dog venous system, which show 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 (3,4,49,50). The innervation was detected, both in vitro and in vivo, as a cholinergic component in neurally evoked contractile responses, which was augmented by anticholinesterase treatment and blocked by atropine.…”

Distribution of cholinesterase in canine venous system.

“…These three veins are embryologically related to the digestive tube, being characterized by the presence of massive longitudinal muscles, spontaneous rhythmic contractile activity, as well as cholinergic excitatory innervation (1 4). Some evidences of the innervation ob tained by in vitro and in vivo experiments were reported (3,(5)(6)(7). Additional findings were reported by Uematsu et al (8).…”

Some Embryological Aspects of Cholinergic Innervation in the Cardiovascular System — A Close Association With the Subintestinal Circulatory Channel

“…By means of a special intravascular cuff, the active tension development of the vascular wall could be recorded quantitatively, while preserving blood flow. A cholinergic constrictor response was recorded when the greater splanchnic nerve, but not the vagus nerve, was electrically stimulated (16). The same result was obtained in the portal vein, and it was occasionally, although slightly, observed in the pulmonary vein (25).…”

“…Nakazato et al (16) demonstrated that in in vivo experiments of dogs, stimulation of the greater splanchnic nerves, but not of the vagus nerve, evoked an atropinesensitive cholinergic response in tension recordings from the middle segment of IVC. Subsequently, a similar finding was observed in recordings from the portal vein (25).…”