Methodology for the determination of the rate of transcytosis in a rat model

This paper describes a methodology which can be used to investigate the possible beneficial effects of oestrogens and other hormones in preventing heart disease. Detailed protocols, including radio-labelled ligand, hormone pre-treatment of animals, the method of the liver transcytosis (studied by bile duct catheterisation) and bile sample analysis by Trichloroacetic Acid (TCA) precipitation were utilised to examine the effects of several different hormones on the rate of transcytosis in Sprague-Dawley (SD) rats (rattus norvegicus) using I-labelled Asialofetuin (ASF). Each rat received a daily subcutaneous (s.c.) injection of estradiol for 3 days. The animals were anaesthetised on day 4 and a catheter was ligated into the bile duct for the collection of bile fluid. Bile samples were precipitated with TCA to determine the amount of non-degraded transcytosed I-ASF collected. The data was expressed as a percentage of the injected dose (% ID) over 75 min to the total % ID accumulated in 75 min for each of the hormones tested.