Effects of age and hyperlipidemia on rabbit coronary responses to neuropeptide Y and the interaction with norepinephrine

In coronary arteries from New Zealand White (NZW) rabbits up to 12 months of age, both direct vasoconstriction to neuropeptide Y (NPY) and inhibition of relaxation to norepinephrine (NE) by NPY were age dependent (p < 0.02 and p < 0.05, respectively); maximal relaxation to NE was unaffected. NPY had no significant effect on arteries from NZW rabbits at 4 months of age, while vessels from Watanabe Hereditable Hyperlipidaemic (WHHL) rabbits showed enhanced direct (p < 0.001) and indirect effects of NPY (p < 0.02). We conclude that the postsynaptic vasoconstrictor effects of NPY on the epicardial coronary artery increase with age and the presence of hyperlipidemia.