Effects of Increasing Age on Vascular Responses of the in vivo Femoral Artery of Adult Beagles

One of the problems associated with using random-source dogs to study in vivo vascular responses is their unknown background. Since aging is known to influence vascular responses, unknown variations in age could influence experimental results. The vast majority of aging studies examine arteries in vitro. This study was undertaken to determine if increasing age of adult beagles influences in vivo femoral artery responses to acetylcholine, norepinephrine, and nitroglycerin. Experiments were performed on three groups: young (3.2 years), middle aged (6 years), and old age (8.7 years). Femoral artery responses (change in diameter, mm) to topical application of increasing concentrations of vasoactive drugs were measured by sonomicrometry. Dose-response relationships to acetylcholine were not different between groups, except at the lowest concentration (-8 log M) where young dogs had enhanced relaxation responses. Constriction to norepinephrine and relaxation to nitroglycerin were not altered by age. Thus, in the in vivo canine femoral artery of adult beagle dogs, vascular responses are essentially unaffected by increasing age.