Effects of hibernation on neural and endothelial control of mesenteric arteries of the golden hamster

The effects of hibernation on mesenteric arterial innervation and function were examined using pharmacological and immunohistochemical techniques in age-matched controls, cold-exposed controls, and 4-wk-hibernated golden hamsters. Electrical field stimulation of the isolated mesenteric arterial bed elicited frequency-dependent vasoconstriction. The sensitivity of responses was significantly increased in tissues from hibernating animals compared with cold-exposed controls. Vasoconstrictor responses to exogenous norepinephrine were also increased in hibernation. However, there was a significant decrease in sensitivity of vasoconstriction to ATP in hibernated and cold-exposed tissue compared with age-matched controls. In preparations preconstricted with methoxamine, endothelium-dependent vasodilator responses to acetylcholine and ATP were similar among the groups. Immunohistochemical investigation of mesenteric arteries revealed no differences among the groups in density of innervation by nerves immunoreactive for tyrosine hydroxylase, neuropeptide Y, and calcitonin gene-related peptide. Postjunctional changes appear to occur in hibernation, leading to augmentation of sympathetic vasoconstriction, which is consistent with the increase in peripheral vascular resistance in hibernation. Endothelium-dependent vasodilatation is not significantly changed in hibernation in the hamster mesenteric arterial bed.