Preparation of the inguinal fat pad for perfusion in situ in the rat: A surgical technique that preserves continuous blood flow

We developed a surgical technique for preparing the inguinal fat pad of rat s for perfusion that preserves continuous blood flow to the tissue. Fatty a cid uptake from the fat pads of fed rats (46.1 +/- 2.1% of arterial supply, n = 82) and release from those of fasted (48 h) animals (51.3 +/- 3.1% of supply, n = 69) occurred principally via the free fatty acid component of t he blood; levels of triglycerides, cholestryl esters, and phospholipids did not change significantly. Venous blood flow in perfusions using blood from fed rats was 83.3 +/- 1.7 mL/min and 83.1 +/- 1.5 mu L/min in experiments involving fasted donors. Values for arterial (A) and venous CV) pH (A, 7.41 +/- 0.03; V, 7.32 +/- 0.04), pO(2) (A, 151.6 +/- 15.7 mm Hg; V, 34.7 +/- 9 .2 mm Hg), pCO(2) (A, 30.8 +/- 6.6 mm Hg; V, 58.2 +/- 5.2 mm Hg), and hemat ocrit (A, 44.6 +/- 1.2%; V, 45.7 +/- 1.2%) were unchanged throughout the co urse of the perfusions, Fat pad and blood perfusates were maintained at 37 degrees C. Tissue homogenates revealed that the total fatty acid content of fat pads fi om fed rats (333.5 +/- 0.3 mg/g tissue) differed significantly from that in fasted animals (260.7 +/- 0.7 mg/g tissue; P < 0.001). Our te chnique likely will have many uses in the study of lipid transport and meta bolism, hyperlipidemia, and cancer-associated cachexia.