[Age-related changes in prostacyclin and thromboxane B2 biosynthesis under normal conditions and in arterial...

An experimental radioisotopic study in normotensive male Wistar rats and spontaneously-hypertensive rats (SHR) of Okamoto--Aoki line demonstrated an age-related increase in the biosynthesis of prostacycline (PGI2) from 14C-arachidonic acid by pulmonary and aortal tissues of animals with normal arterial pressure. In SHRs, PGI2 production by lung homogenates did not change essentially with age, but decreased considerably in adult SHRs with stable hypertension. PGI2 biosynthesis by SHR's aortal tissue decreased with age and dropped significantly as arterial hypertension developed. In normotensive rats, the formation of thromboxane B2 (TxB2) by platelets increased with age. Platelet TxB2 biosynthesis was elevated considerably both in young and adult SHRs. Clinically, a significant increase of platelet TxB2 production from exogenous 14C-arachidonic acid was demonstrated in children with essential hypertension.