Tissue Distribution of [1 14 C]Cholylglycine in Rats and Hamsters with a Bile Fistula or Bile Duct Ligation 1

Abstract

Plasma disappearance of substances taken up largely by the liver, such as bromosul-fophthalein (BSP) (1-3) or indocyanine green (4, 5), has been used widely as a test for liver function. Recently, the plasma disappearance of a bile acid, cholylglycine, has been proposed as a test for hepatic injury (6, 7). This bile acid clearance is based on the assumption that the plasma disappearance of cholylglycine may be equated with hepatic uptake. To test this assumption, we have defined the tissue distribution of intravenously injected cholylglycine in rats and hamsters; we have used animals with an acute bile fistula, as well as animals with a bile duct obstruction.

Materials and methods. Experimental design. A mixture of [l-¹⁴C]cholylglycine and [⁹⁹Tc]albumin was injected intravenously as a bolus. Ten minutes later, animals were killed and tissues were removed for determination of radioactivity. The⁹⁹Tc was used to estimate the amount of blood contaminating each tissue sample. The sampling time of 10 min was chosen since this time interval corresponds to about three half-lives for plasma disappearance of cholylglycine (in man) (8) and was judged to be a sufficiently long interval for nearly complete tissue uptake to occur.

Chemicals. [1-¹⁴C]Cholylglycine (sp act 51.7 mCi/mmole) was purchased from Amersham/Searle (Arlington Heights, 111.) and had a radiopurity greater than 96% by zonal scanning (9) using a thin-layer system for bile acid conjugates (10). [⁹⁹Tc]Albumin was prepared using a commercial kit (New England Nuclear Radiopharmaceutical Division, North Billerica, Mass.). A solution of [l-¹⁴C]cholylglycine was mixed with [⁹⁹Tcjalbumin to give a concentration of 5 μCi of ^I4C and 15 μCi of ⁹⁹Tc radioactivity per milliliter.

Animal preparation. Male Sprague-Daw-ley rats weighing 250-350 g (Mayo Clinic stock) and adult golden Syrian hamsters (Engel Laboratory, Farmersburg, Ind.) were used.