IN-VIVO SPIN-TRAPPING OF GLYCERYL TRINITRATE-DERIVED NITRIC-OXIDE IN RABBIT-BLOOD VESSELS AND ORGANS

Background The objectives of this study were (1) to assess glyceryl tr initrate (GTN)-derived nitric oxide (NO) formation in vascular tissues and organs of anesthetized rabbits in vivo, (2) to establish a correl ation between tissue NO levels and a biological response, and (3) to v erify biotransformation of GTN to NO by cytochrome P-450. Methods and Results NO was trapped in tissues in vivo as a stable paramagnetic mon onitrosyl-iron-diethyldithiocarbamate complex [NOFe(DETC)(2)]. After r emoval of the tissues, NO was determined by cryogenic electron spin re sonance spectroscopy. NO formation in vitro was assessed by spin trapp ing and by activation of soluble guanylyl cyclase. The GTN-elicited de crease in coronary perfusion pressure was monitored in isolated, const ant-flow perfused rabbit hearts. NO was not detected in control tissue s. In GTN-treated rabbits, NO formation was higher in organs than in v ascular tissues and higher in venous than in arterial vessels. In isol ated hearts, ventricular