Relationship between the hydralazine-induced changes in murine tumor blood supply and mouse blood pressure

The relationship between hydralazine-induced changes in blood pressure and tumor blood flow was investigated in restrained but non-anesthetized CDF1 mice bearing C3H/Tif foot tumors. Mean arterial blood pressure measurements were made using the procedure of carotid cannulation, and tumor blood flow was estimated using laser Doppler flowmetry. Hydralazine doses from 0.1 to 5.0 mg/kg were tested. Following hydralazine administration the maximum changes in blood pressure and blood flow were apparent within 10-15 min and were maintained for at least 30 min after injection. Blood pressure decreased with increasing hydralazine dose, achieving a maximum reduction of 50% at 2.5 mg/kg. Tumor blood flow was found to be increased by 30% at the lowest hydralazine dose (0.1 mg/kg), even though blood pressure was decreased by 10% at this dose. At hydralazine doses producing a 15% or greater blood pressure drop, blood flow decreased, reaching an 80-90% reduction between 2.5 and 5.0 mg/kg.