Age related changes of platelet prostacyclin receptors in humans

Abstract

Platelet receptors for PGI2 were investigated in eighteen healthy volunteers divided in two classes of age: nine were 18-40 years old and nine were 41-65 years old. PGI2 platelet receptors were found to decrease significantly with age; the young subjects had 106 +/- 16 (mean +/- SD) high affinity receptors/platelet and 3509 +/- 529 low affinity receptors/platelet whereas the old subjects had 86 +/- 14 high affinity receptors/platelet (P less than 0.02) and 2471 +/- 640 low affinity receptors/platelet (P less than 0.005). The cumulated data from all the subjects yielded a significant negative correlation with age (r = -0.71, P less than 0.001 for the high affinity class and r = -0.65, P less than 0.01 for the low affinity class). The affinity of receptor sites for the ligand did not statistically change with aging (P less than 0.30 and P less than 0.90 respectively for high and low affinity receptors).

Alterations in Platelet Function During Aging: Clinical Correlations with Thromboinflammatory Disease in Older Adults

“…Platelet alpha 2‐adrenergic receptor density and receptor‐mediated inhibition of adenylyl cyclase, which mediate platelet aggregation, are also lower in healthy older adults than in younger adults, contributing to a propensity toward platelet activation and homotypic aggregation responses . Older adults also have lower platelet surface prostacyclin (PGI 2 ) receptor density, greater platelet resistance to PGI 2 inhibition, and greater urinary excretion of prostacyclin metabolites than younger adults . PGI 2 is an eicosanoid that inhibits platelet aggregation and leads to vasodilation.…”

The bleeding time in women

“…The tendency towards a shorter BT in postmenopausal than in pregnant women might be an effect of age (6,15,16,17) and not of hormones. Apart from these observations, several studies indicate an enhanced age related platelet activity which may influence the risk of coronary heart disease (15)(16)(17)(18)(19)(20). Trying principally to study hormonal effects, our subjects were selected to achieve a small age difference between pre-and postmenopausal women.…”

Thrombocytopenia in Older Adults

“…51 The platelet surface prostacyclin receptor density is also lower, leading to less inhibition of platelet aggregation by prostacyclin. 52,53 Platelet nitric oxide synthase is decreased. 54,55 The increased platelet reactivity is also reflected by increased levels of β thromboglobulin and platelet factor 4 levels in the plasma.…”