BRONCHIAL ARTERIAL RESPONSE TO CONTRAST-MEDIUM

Rationale and Objectives. Contrast agents have been shown to produce v asodilatory responses in several vascular beds. To our knowledge, howe ver, their effect on the bronchial vasculature has not been examined. Clinically, contrast-induced bronchial vasodilation could potentially exacerbate life-threatening pulmonary hemorrhage during bronchial angi ography for hemoptysis. In the current study, we systematically measur ed the bronchial vasodilatory response to diatrizoate meglumine 66% an d diatrizoate sodium 10% (MD-76) and examined whether vasodilation wou ld be mediated by nitric oxide (NO). Methods. We measured bronchial bl ood flow in seven anesthetized, ventilated, open-chested sheep using a n ultrasonic flow probe placed around the bronchial artery. Bronchial blood flow was recorded before and after injection of 2 ml MD-76 into the bronchial artery. The protocol was repeated after 20 min infusion of N-omega-nitro-L-arginine (L-NA; 10(-2) mol/l), an NO-synthase inhib itor, into the bronchial artery. Results. There was a 45 +/- 8 ml/min increase (p <.01) in bronchial blood flow after injection of MD-76, wh ich was reduced to 20 +/- 6 ml/min (P <.01) after infusion of L-NA. Co nclusion. Bronchial arterial injection of MD-76 results in a consisten t increase in bronchial blood flow that is mediated partly by NO.