Dietary salt-loading attenuates endothelium-dependent relaxation in response to histamine but not to acetylcholine in rat aortic rings.

Endothelium-dependent relaxation in response to histamine and ACh has been studied on precontracted aortic rings from control and salt-loaded Sprague-Dawley rats. Both ACh and histamine caused relaxation of the noradrenaline-induced precontraction only in the presence of the endothelium. The relaxation response to ACh in rings from control and salt-loaded rats did not differ significantly whereas histamine-induced relaxation was significantly attenuated in aortae from salt-loaded rats. The results suggest that salt-induced hypertension is associated with impairment of endothelium-dependent relaxation to histamine but not to ACh.