Platelet alpha-adrenoceptor function and aging

Abstract The effect of aging on platelet alpha-adrenoceptor binding of 3 H-dihydro-alpha-ergocryptine (3H-DHE) and alpha-adrenoceptor response expressed as cAMP de-crease, after the addition of noradrenaline 10 uM to intact platelets in vitro were examined and correla-ted with adrenaline induced platelet aggregation in a group of twelve young volunteers (mean age 21 years), and twelve old volunteers (mean age 88 years). The binding by platelets of 3 H-DHE was considerably hig-her in the young than in the old group (mean 292.70 ± 40.79 and 167.90 ± 18.30 fmol/mg protein respective-ly, p d ) was also influenced with values of 1.49 ± 0.21 in the young and 3.32 ± 0.45 nM in the old, p 9 platelets. Platelet sensitivity to adrenaline, when expres-sed as aggregation increased in the old group. These data suggest that the enhanced sensitivity to adrenaline as observed in old people is not the result of increased alpha-adrenoceptor number or affinity, but related to changes in the platelet membrane possibly not related to the alpha-adrenoceptors.