A modified rat model for cannulation and collection of thoracic duct lymph

Difficulty in collecting lymph samples in small animals has impeded studies on lymphatic function and lymph composition. Here we report a simple and effective modified rat model for thoracic duct lymph drainage where animals remain in full consciousness and have free movement and access to water and food over 12 hours. The operative procedure required approximately 30 minutes to perform. Mean lymph drainage was 0.71 +/- 0.33 ml/h, and protein concentration did not change significantly (mean 37 +/- 2.59 mg/ml) over the 12 hours. However, the number of lymphocytes fluctuated widely between 0.08 +/- 0.03 x 10(6)/ml and 12.17 +/- 6.58 x 10(6)/ml. This modified animal model of thoracic duct lymph collection avoids influences of lipid intake, general anesthesia, or limited activity of animals on experimental outcomes, and therefore more accurately reflects lymph flow and composition under normal physiological conditions.