A new technique of in vivo synchrotron radiation coronary microangiography in the rat

Abstract

Background Previously, in our laboratory, synchrotron radiation coronary microangiography (SRCA) using Langendorff-perfused rat hearts could visualize a coronary artery of 50 µm in diameter. However, in vivo rat SRCA poses the problem of compromised temporal resolution due to the rapid heart rate of rats. Purpose To establish a simple method of in vivo rat SRCA with bradycardia induced by intravenous injection of adenosine triphosphate disodium hydrate (ATP). Material and Methods SRCA was performed at the Photon Factory of the High Energy Accelerator Research Organization (Tsukuba, Japan). Eight male Wistar rats were anesthetized. A catheter for injecting the contrast material was inserted into the carotid artery. Temporary bradycardia was induced by an intravenous bolus injection of 5 mg of ATP, and SRCA was performed immediately thereafter. Results After ATP administration, the average heart rate decreased from 388 to 73 beats per minute. As a result, we could detect a coronary artery as small as 45 µm in diameter. Conclusion Our SRCA system which has a high resolution of 9 µm per pixel could detect a coronary artery as small as 45 µm in diameter in the in vivo rat.