Response of neoplastic and normal vasculature to acetylcholine

Intravascular acetylcholine causes vasodilation and an increase in normal tissue blood flow and could reasonably be expected to increase blood flow in malignant neoplasms. In this study using the microsphere reference sample technique, however, blood flow of V2 carcinoma, implanted in several organ sites in rabbits, was found to decrease after both an intra-arterial bolus and infusion of acetylcholine chloride. Cardiac output was not significantly changed. These observations may explain the recent report by Marincek et al. of a decrease in CT X-ray absorption in renal neoplasms after acetylcholine and previous reports of the lack of utility of vasodilators in improving the diagnosis of malignant neoplasms after arteriography.