Dynamics of blood nitric oxide level during nitric oxide inhalation.
Nitric oxide (NO) which is produced from L-arginine by nitric oxide synthase (NOS) is a key molecule in regulation of hemodynamics and organ blood flow. Inhalation of NO has been applied in various diseases, such as pulmonary hypertension and prevention of chronic lung disease in the newborn, congenital heart disease, lung transplantation, acute respiratory distress syndrome, and chronic obstructive pulmonary disease. Although inhalation of low levels of NO appears to be safe and cause a rapid increase in lung blood flow without causing systemic hypotension, influence of NO inhalation to the kinetics of NO in the systemic circulation has not been clarified. Therefore, we have measured the plasma NO concentration in the porcine aorta and femoral artery by employing the NO-selective electrodes during NO inhalation. We located the NO sensors through a 5-Fr sheath in the aortic arch and left femoral artery. NO was administered with a NO inhalation device from a respirator. While inhaling NO (1 and 10 ppm), plasma NO concentration increased both in the aortic arch and in the left femoral artery. The inhalation of NO influences the kinetics of NO in blood beyond the pulmonary circulation.