Functional and structural changes in the rabbit ear artery after sympathetic denervation.

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Abstract
We studied the tissue weight, dimensions, contractility, elasticity, and sensitivity to exogenous norepinephrine (NE) of denervated and innervated segments of the central ear arteries of white New Zealand rabbits. Three different age groups received unilateral superior cervical ganglionectomies, "growing" at 3-4 weeks, "young adult" at 9-11 weeks, and "mature" at 16-20 weeks. In the growing group, 8 weeks after ganglionectomy, the denervated arteries showed mean decreases in tissue weight (11%), total wall thickness (12+), cross-sectional area of media (17%), contractility (16%), and increases in the tangential modulus of elasticity and sensitivity to NE (2.3-fold) compared to the contralateral control vessels. The change in medial cross-sectional area was significant in the growing and young adult but not the mature animals. The other changes, however, although consistently seen, differed quantitatively among the groups. These results indicate that an intact innervation is necessary for normal development and maintenance of the artery wall. However, the precise consequences of this influence vary at different ages. Whether this influence involves a special trophic factor is not known.