The innervation pattern of guinea-pig pulmonary vasculature depends on vascular diameter. Haberberger, Rainer, Michael Schemann, Holger Sann, and Wolfgang Kummer. Institut f[umlaut]ur Anatomie und Zellbiologie, Justus-Liebig- Universit[umlaut]at Giessen, Aulweg 123, D-35385 Giessen, Germany, Physiologisches Institut, Tier[umlaut]arztliche Hochschule, Bischofsholer Damm 15 / 102, D-30173 Hannover, Germany
APStracts 3:0471A, 1996.
The pulmonary vasculature is supplied by various neurochemically distinct types of nerve fibers, including sensory substance P- containing and autonomic noradrenergic, nitrergic, and cholinergic axons. Pharmacological experiments have suggested that various segments of the pulmonary vascular tree respond differently to the respective neuromediators. We, therefore, aimed to determine histochemically and immunohistochemically for each of these neurochemically distinct perivascular axons their quantitative distribution along the vascular tree from extrapulmonary trunks to smallest intraparenchymal ramifications in control guinea-pigs (N = 5). Generally, arterial innervation was more developed than that of veins. Along the arterial tree, noradrenergic and substance P -containing axons were ubiquitous from the pulmonary trunk to smallest intraparenchymal vessels, while nitrergic axons were practically restricted to large (>700 _m) extrapulmonary arteries. Cholinergic axons were regularly present at arteries down to 100 _m in diameter and innervated two thirds of small arteries (50 - 100 _m). The results demonstrate that the noradrenergic vasoconstrictor innervation extends throughout the pulmonary vascular system whilst the innervation pattern with various types of vasodilator fibers changes with vascular diameter, parallel to known pharmacological differences in cholinergic and nitrergic vasodilator effects. 

Received 4 December 1995; accepted in final form 1 October 1996.
APS Manuscript Number A1249-5.
Article publication pending Journal of Applied Physiology.
ISSN 1080-4757 Copyright 1996 The American Physiological Society.
Published in APStracts on 5 November 1996