NEUROCOMPENSATORY RESPONSES TO BALLOON-CATHETER-INDUCED INJURY OF THERAT CAROTID-ARTERY

Percutaneous transluminal angioplasty relieves discrete arterial steno sis but causes extensive vascular injury. There is denudation of the e ndothelium and variable medial disruption, but the effect on adventiti al structures has not been studied in detail. We have investigated the innervation of the left and right carotid arteries after unilateral b alloon-catheter-induced injury. Immunohistochemical examination of the arteries 1 day after Fogarty-catheter-induced injury of the left comm on carotid artery revealed a reduction in the density of protein gene product 9.5 (PGP)-, substance P (SP)- and calcitonin-gene-related pept ide (CGRP)-containing nerves close to the medial smooth muscle of the injured vessel. At the same time, on the side contralateral to the inj ury, there was a substantial increase in the density of PGP-, SP- and CGRP-containing nerves innervating the carotid artery and vasa vasorum compared to controls. Immunoassay data from these vessels showed a se lective increase in SP and CGRP contents of the contralateral carotid artery (SP, controls 0.02 +/- 0.01, operated 0.59 +/- 0.32 pmol/cm; CG RP, controls 0.03 +/- 0.01, operated 0.14 +/- 0.03 pmol/cm, n = 6, p < 0.05). Neuropeptide Y levels were unchanged. Twenty-eight days after surgery, at which time a neointima was present, peptide levels were no different from controls, and the innervation of both the left and rig ht carotid arteries and vasa vasorum was indistinguishable from the co ntrols. In conclusion, balloon-catheter-induced injury includes damage to the perivascular nerves and induces a transient increase in the de nsity of sensory neuropeptide-containing nerves innervating the contra lateral, uninjured side. This novel observation may reflect neurocompe nsatory responses to vascular injury.