Changes in vasoconstrictor and vasodilator responses of the basilar artery during maturation in the Watanabe heritable hyperlipidemic rabbit differ from those in the New Zealand White rabbit.

This investigation involved alterations in the local control of vascular tone in the isolated rabbit basilar artery in atherosclerosis, with Watanabe heritable hyperlipidemic (WHHL) rabbits as a model and New Zealand White (NZW) rabbits as controls. Vasoconstrictor responses to KCl in isolated preparations of the basilar artery at basal tone showed no differences at 4, 6, and 12 months of age in either WHHL or NZW rabbits. Contractile responses to both histamine and neuropeptide Y were significantly greater in 12-month-old WHHL rabbit preparations when compared with responses measured at 4 and 6 months. In NZW rabbit preparations, there was no change in maximum contractile responses to both histamine and neuropeptide Y over the same age range. Endothelium-dependent relaxations to acetylcholine in raised-tone preparations from WHHL rabbits were significantly greater at 6 months in comparison with responses measured at both 4 and 12 months of age. In contrast, endothelium-independent relaxations to calcitonin gene-related peptide and vasoactive intestinal polypeptide showed no change over the age range studied. In NZW rabbit preparations, both endothelium-dependent and endothelium-independent relaxations declined significantly between 4 and 12 months. The significance of these changes in the rabbit basilar artery in atherosclerosis is discussed in relation to the "protection" of intracranial arteries from atherosclerosis and their subsequent susceptibility to cerebral ischemia and stroke.