Measurement of organ blood flow using 4 different non-radiated dye extraction colored microspheres in rat abdominal hypertension models

Objective To investigate the feasibility and accuracy of the using 4 different colored non-radiated dye extraction colored microspheres to measure multiple organs blood flow in one rat,which sustained four conditions of intra-abdomiual pressuring.Methods An inflatable gasbag was inserted into abdominal cavity of rat,which was used to create the model of non-pneumatic intra-abdominal pressure (IAPx) [x =0,5,10,15 mm Hg (1 mm Hg=0.133 kPa) ].Each condition of IAPx sustained 10 min.One of the four non-radiated colored dyed microspheres was infused through cannulation tube in the left ventricle in the sequence of pink,yellow,white and purple.After drawing reference blood sample,complementay blood was transfused in an equal amount from another transfusion rat.The interval time was 15 min.All six rats were suffered from the four conditions of intra-abdominal pressure.At the end of the experiment,animals were killed by intravenous injection of saturated potassium chloride solution,and aimed organ samples were harvested.The organ blood flows were calculated after a sequence of dealing with samples,such as alkaline digesting,ultrasonography cell crashing,DMF dying extraction,and the dye concentration was quantified by spectrophotometry.Tissue blood flow was calculated by an equation:Organ blood flow =[ AU per gram of tissue ] × [ reference withdrawal rate ] / [ AU per gram of reference blood ].Results All animals were endured the four conditions (0,5,10,15 mmHg) of intra-abdominal pressure.The distribution of microspheres in the blood flow was uniform,and the blood flow through the right kidney and left kidney was matched equally:for left kidney [ (2.02 ±0.47),( 1.39 ±0.62),(0.81 ±0.24),(0.22 ±0.09) ml·(min·g) ]; For right kidney [(2.23 ±0.26),(1.38 ±0.61),(0.89 ±0.31),(0.24 ±0.09) ml/(min·g),F=0.177,P＞0.05],and had close correlation (P＜0.01,R =0.687).With the increase of the abdominal pressure from 5 to 10 mmHg,the blood flow of abdominal organs ( such as liver)was decreased significantly [ Hepatic artery:(0.16 ± 0.05 ),(0.15 ± 0.03 ),(0.10 ± 0.03 ),(0.02 ±0.01) ml·(min·g) ; Portal vein:(1.73 ±0.41),(1.19 ±0.21),(0.83 ±0.18),(0.38±0.08) ml/(min·g) ].On the other hand,the blood flow of the vital organs (such as heart and brain) was maintained in the abdominal pressure of 5-10 mm Hg.When the abdominal pressure was increased to 15 mmHg,the blood floow of the vital organs showed the decreased tendency [ Heart:(2.56 ± 0.95 ),( 1.69 ± 0.95 ),(1.44±0.41),(0.71±0.24)ml/(min·g); Brain:(0.49±0.09),(0.22±0.07),(0.22±0.06),(0.19 ±0.02) ml/(min·g) ].The recovery rate of microspheres was (92.0 ±7.1 )％.Conclusion The use of dye extraction colored microspheres should allow to undergo hemodynamic study on different organ blood flow in one animal.The method is feasible and accurate,especially suitable for small animals. Key words: Intra-abdominal hypertension;  Non-radiated colored microsphere;  Hepatic bloodflow