Pharmacological modifications of the partial pressure of oxygen in murine tumors: Evaluation using in vivo EPR oximetry

EPR oximetry using an implantable paramagnetic probe was used to quantify the partial pressure of oxygen (pO2) in tissues in a transplantable mouse tumor model (TLT) after administration of 34 different vasodilators belonging to one of the following classes: angiotensin‐converting enzyme inhibitors, calcium antagonists, alpha antagonists, potassium channel openers, beta‐blockers, NO donors, and peripheral vasoactive agents. Twenty‐four compounds were efficient in significantly increasing the local pO2 in a majority of tumors. The increase of local pO2 using pharmacological treatments was lower than that achieved by using oxygen or carbogen breathing. This technique offers an unprecedented tool for rapidly and accurately measuring treatment‐induced modifications of pO2 in tumors. Magn Reson Med 42:627–630, 1999. © 1999 Wiley‐Liss, Inc.