Sympathetic nerves exert a chronic influence on the intact vasculature that is age related.

The hypothesis of this study is that the chronic presence of intact sympathetic innervation influences the structure, and thereby function, of the rabbit ear vascular bed, and that this influence may be age related. Therefore we examined the effect of chronic sympathetic denervation on vascular resistance of the rabbit ear nine to ten weeks after unilateral superior cervical ganglionectomy. Two age groups were studied: growing juvenile rabbits denervated at 4 weeks of age and adult rabbits denervated at 16 weeks. We assessed the flow-pressure (resistance) curves of the chronically denervated and contralateral innervated isolated rabbit ears during maximum dilation. The flow-pressure curve was significantly shifted downward in the denervated compared to the contralateral innervated ears of juvenile rabbits operated on at 4 weeks (p less than 0.001) but was not different in adult rabbits operated on at 16 weeks. These results support the concept that the sympathetic nerves chronically influence blood vessel properties in growing animals, apart from their acute effect on vasomotor tone.