EFFECTS OF AGE ON THE RELEASE OF ADENINE NUCLEOSIDES AND NUCLEOTIDES FROM RAT CAUDAL ARTERY

1. The spontaneous and a-adrenoceptor-induced release of ATP, ADP, AMP and adenosine were determined from arterial segments and from isolate d endothelial cells from caudal arteries of young (5-week-old), adult (30-week-old) and old (100- to 110-week-old) Wistar rats. 2. The spont aneous (non-evoked) release of the sum total of the four purines was s ignificantly greater from artery segments of young rats than from adul t and old rats. 3. The release of the adenine nucleotides and adenosin e induced by methoxamine (10 mu M), an alpha(1)-adrenoceptor agonist, was greater from artery segments from young rats than from old rats. 4 . The spontaneous release of the sum total of the four purines was sig nificantly greater from endothelial cells prepared from caudal arterie s of young rats than of old rats. 5. The noradrenaline (10 mu M)-induc ed release of the sum total of the four purines was significantly grea ter from endothelial cells prepared from caudal arteries of young rats than of old rats. 6. The levels of adenine nucleotides and adenosine, determined in plasma from anaesthetized rats, were significantly high er in young rats compared with adult and old rats. 7. These findings s uggest that the release of ATP from the vascular endothelial cells is reduced with advancing age.