Autonomic Nervous SystemEndothelin in perivascular nerves. An electronimmunocytochemical study of rat basilar arteryLoesch, Andrzej1,3; Milner, Pamela1,2; Burnstock, Geoffrey1,2Author Information 1Department of Anatomy and Developmental Biology and Centre for Neuroscience, University College London, Gower Street, London WC1E 6BT, UK 2Autonomic Neuroscience Institute, Royal Free Hospital School of Medicine, Rowland Hill Street, London NW3 2PF, UK 3Corresponding Author: Andrzej Loesch ACKNOWLEDGEMENTS: The authors thank Mr R. Jordan for editorial assistance and Mr. M. Miah for skilful technical assistance. The support of the British Heart Foundation is gratefully acknowledged. Received 12 August 1998; accepted 23 September 1998 NeuroReport: December 1st, 1998 - Volume 9 - Issue 17 - p 3903-3904 Buy Abstract THE endothelium is recognized as a major source of endothelin in the vasculature. In this report we show for the first time that endothelin can be demonstrated with immunoelectronmicroscopy in perivascular nerves. About 36% of the axon profiles (varicosity/intervaricosity) examined in the rat basilar artery showed immunolabelling with a polyclonal antibody to endothelin-1. Endothelin-labelled axon varicosities were characterized by the presence of small spherical agranular vesicles (42 ± 1 nm); some varicosities also contained large granular vesicles (++ ±5 nm) with labelled cores. Immunolabelling was mostly distributed in the axoplasm and in association with the membrane of synaptic vesicles (the lumen of the small agranular vesicles was immuno-negative). The presence of endothelin in perivascular nerves of the basilar artery suggests a neuronal as well as endothelial role in the physiological control of the vessel wall. © 1998 Lippincott Williams & Wilkins, Inc.