Effect of aging on arteriolar dilatation induced by prostaglandin E(1) incorporated in lipid microspheres

To investigate the effect of aging on vasodilation of arterioles induced by prostaglandin E(1) incorporated in lipid microspheres (lipo-PGE(1)), we measured the diameter of the anterior ciliary artery in patients aged <65 years (young group) and in patients aged >65 years (elderly group). An eyelid retractor was affixed to the right eyelid while patients were under general anesthesia, and changes in the diameter of the arteriole were continuously monitored by surgical stereomicroscopy for 10 min after the intravenous (i.v.) injection of lipo-PGE(1) (0.2 mu g/kg). We also measured mean arterial pressure (MAP) and heart rate (HR) during the study. The diameter of the arteriole in the young group began to increase significantly 1 min after the injection (p < 0.01), reaching the maximal increase (42.3 +/- 7.4% above the preinjection level) at 3 min after continuous dilatation at the end of the study. In the elderly group, the diameter began to increase 2 min after the injection (p < 0.01), reached the maximal value (33.2 +/- 12.7% above the preinjection level) at 5 min, and then gradually decreased to the baseline value. MAP decreased continuously after the injection in both groups; there was no significant difference between the groups. HR in the young group began to increase after the injection and then returned to the baseline level, but in the elderly group it showed continuous increase throughout the study. These results suggest that aging impaired the vasodilatory response to lipo-PGE(1), in the anterior ciliary artery.