A method for continuously assessing coronary blood flow velocity in the rat.

We have developed a directional pulsed-Doppler system to make blood flow velocity measurements in the coronary arteries of the rat. The probe consists of a 1-mm2 crystal mounted in a 6-mm suction cup, which can be attached by vacuum to the vessel without requiring dissection. Recordings of phasic coronary blood flow velocity (CBV) in the rat indicate that 82 +/- 2% (mean +/- SE) of the area under the CBV recording occurs in diastole. CBV increased during an infusion of dipyridamole and changed in parallel with alterations in left-ventricular pressure. To validate the technique we correlated changes in CBV wih changes in microsphere-measured left-ventricular perfusion (range, 20--780 ml/min x 100 g). These two methods of estimating coronary flow correlated closely (r = 0.93). Measurements of phasic CBV in the rat with this Doppler system should permit a detailed characterization of the coronary circulation in many models of disease that have been developed in the rat.