Decline in beta adrenergic receptor-mediated vascular relaxation with aging in XXXX .

@entity1 @entity1242 @entity477 @entity1919 @entity2647 @entity3044
Beta adrenergic relaxation of vascular smooth muscle, mediated by @entity1919 , is blunted with age in a variety of experimental animals. The applicability of these observations to @entity1 is uncertain. The dorsal hand vein technique provides an excellent method to examine the direct effects of aging on vascular responsiveness. Thirty-nine healthy male volunteers over the age range of 19 to 79 were studied. No differences in vascular responsiveness to @entity2647 , an alpha adrenergic agonist, were found for either the ED50 (dose producing 50% vasoconstriction) or Emax (maximum vasoconstriction attained). In marked contrast, vascular relaxation induced by @entity3044 , @entity477 adrenergic agonist, was significantly different in both the ED50 (dose producing 50% of maximum relaxation from a preconstricted state) and Emax (maximum relaxation attained). ED50 +/- S.E.M. for the youngest and oldest deciles were 8.9 +/- 2.3 and 60 +/- 17.0 ng/min, respectively (P less than .05); Emax +/- S.E.M. were 96.7 +/- 3.3 and 37.7 +/- 8.7%, respectively (P less than .001). @entity1242 , a smooth muscle relaxant whose effects are not mediated through the @entity1919 system, was also used to examine the specificity of this blunted response to @entity3044 . Almost complete relaxation was achieved with the infusion of @entity1242 in the older group. These results suggest that aging is associated with a specific decrease in beta adrenoreceptor-mediated vascular relaxation.
