LIGHT-ACTIVATED RELEASE OF NITRIC-OXIDE FROM VASCULAR SMOOTH-MUSCLE OF NORMOTENSIVE AND HYPERTENSIVE RATS

A porphyrinic sensor was used to monitor nitric oxide release from vas cular smooth muscle in response to exposure to ultraviolet light. Aort ic rings exposed to W light relaxed with a time course that parallels this observed NO release. With repeated UV light treatments, the magni tude of the relaxations diminished, suggesting that a store of NO was being exhausted. Photorelaxation in response to W light was studied in aortic rings from two types of hypertensive rats, genetic (SHRSP) and nitroarginine-induced. These aortic rings showed greater photorelaxat ion and evidenced less tolerance than did aortic rings from control no rmotensive rats. Since NO synthase activity is depressed in both types of hypertension, it appears, paradoxically, that the UV light-releasa ble store of NO is augmented when NO synthase activity is depressed. ( C) 1994 Academic Press, Inc.