Rapid method for homogenizing tissue samples for liquid scintillation counting.

EVALUATiON OF A new drug includes analysis of its tissue distribution. We have developed an improved method for solubilizing tissues that is not only rapid, but results in a homogeneous sample for counting. We had found that organs rich in connective tissue (heart, lung, skeletal muscle, urinary bladder, stomach, and intestinal wall) could not be completely disrupted by conventional techniques such as homogenization, sonication, or lyophilization followed by pulverization. In the present procedure, a great number and variety of animal tissues with different water, lipid,and fiber content have been rapidly and completely pulverized after quick-freezing in liquid nitrogen. The powdered tissue was mixed with NCS (Nuclear-Chicago Solubilizer), a solubiliziiig agent described by Hansen and Bush (1). When the sample became homogeneous, the scintillation “cocktail” was added and the sample counted. Using items normally found in the biochemical laboratory, we developed a method for completely pulverizing samples of the aforementioned tissues. In addition to the liquid nitrogen, the only item which had to be purchased was an 8-liter evacuated flask (Virtis Fluo-War) for transporting the liquid nitrogen. The following supplies are necessary: A support rod, 13 mm in diameter and 45 to 61 cm long, made of solid extruded aluminum; a metal cylinder or pipe, open at both ends and 20 to 30 cm long, with au inside diameter of 2 to 2.5 cm (we used the overflow drain tube from the laboratory sink); a pair of blunt-nose forceps, 20 to 25 cm in length; several stainless steel cups, 45 mm in diameter (we used rat food cups obtained from the Acme Cage Co.); and a pair of thick leather gloves. With the forceps, a 5-g or smaller sample of organ or tissue is placed in a stainless steel cup, which is then filled with liquid nitrogen. When the sample is frozen, the metal cylinder is placed over the sample and the aluminum rod is inserted (Fig. 1). A small amount of liquid nitrogen (20 to 50 ml) is poured intothe cylinder to ensure that the sample is frozen and the metal components surrounding it are as cold as possible. Using a piston-like motion, the rod is raised and lowered with a