Direct measurement of nitric oxide in the cardiovascular system.

Nitric oxide generated from L-arginine is a messenger for cell-to-cell communication. Abnormalities in nitric oxide release have been implicated in diseases ranging from hypertension and atherosclerosis to septic shock and rheumatoid arthritis. We report here the in vivo and in vitro measurements of nitric oxide in the cardiovascular system using a porphyrinic sensor specific for NO. The sensor has a detection limit 10(-9) M, response time of 0.1-10 ms and diameter of 1-20 microns. Protected by an intravenous catheter or Swan-Ganz catheter, the sensor can be implanted into tissues as well as into the blood stream. Nitric oxide concentrations were measured directly in the heart and also in veins and arteries, ranging in diameter from 100 microns to 5 mm. Nitric oxide production was induced by the action of different physical agents (shear stress, stretching) as well as various chemical substances agonists (bradykinin, acetylcholine, ATP).