In vivo pressure-flow curve in unilateral rat lung ischemia-reperfusion injury

The pressure-flow (P-Q) curve has been widely used in many studies to descr ibe the effects of various factors on vascular hemodynamics. It is not clea r, however, whether unilateral ischemia-reperfusion (IR) alters the P-Q cur ve of the rat lung. In this study, we developed an in vivo P-Q curve using the unilateral (left) rat lung before and after IR. Animals were divided in to two groups: sham and IR. The protocol of the IR group consisted of three periods: baseline, ischemia, and reperfusion. P-Q curves were obtained by altering blood flow of the left lung during the baseline and the reperfusio n periods. The sham group received the same operation without IR procedure. An additional group was used to compare pulmonary blood flow measured by t he microsphere and the ultrasonic methods. IR treatment rotated the P-Q cur ve toward the left, indicating an increase in resistance in the left lung. However, this rotation was not found in the sham group. A significant corre lation (r = 0.87, P < 0.01) between percentages of blood flow obtained by t he microsphere and ultrasonic methods in both right and left lungs was demo nstrated. Therefore, we demonstrated a simple and useful technique to evalu ate changes in the P-Q curves caused by IR in the unilateral rat lung model .