Reactivity of neonatal canine aortic strips

To determine whether vascular reactivity in the young animal is significantly different from that of the mature animal, helical strips of thoracic aorta were suspended in an organ bath of Krebs bicarbonate solution, and isometric tension was measured. The effects of norepinephrine, phenylphrine, tyramine, and KCl were studied. The neonatal vascular strips were less sensitive than adult strips to the adrenergic agents, but responsiveness to KCl was comparable in both groups.