Contractile response of normotensive rat aorta to serum from salt-loaded Sprague-Dawley rats

Sprague-Dawley rats were made hypertensive by 6-week dietary salt loading with 8% NaCl in the diet and compared with control rats which had normal feed and water. At the end of this period, the salt-loaded group developed hypertension but the heart rate did not differ significantly from control. Serum taken from salt-loaded rats showed enhanced vasoconstrictor effect on normal rat's aorta when compared with controls. This enhanced vasoconstrictor effect was attenuated by adrenergic receptor blockers but not by serotoninergic blockers. Thus salt loading may induce accumulation of vasoactive agents in the blood of rats.