Figure 1. Relaxation of precontracted descending thoracic aortic rings in response to increasing concentrations of acetylcholine (A) or nitroprusside (B). Open circles = normothermic cardiopulmonary bypass (n = 8); filled circles = hypothermic cardiopulmonary bypass (n = 7); open squares = non-cardiopulmonary bypass (n = 8). Values are mean +/- SD.