All urine and feces were collected in 13 X 100-mm bo-rosilicate tubes separately at 4, 8, 12, 16, 24, 36, 60, 84, 108, 156, and 228 h for Peromyscus and at 4, 8, 12, 25, 35, 57, 98 h for Mus from the time of injection. Fecal samples were weighed, and urine volumes were estimated by comparison with known volumes. Urine (50 pl) from each time point was suspended in 4 ml triton-toluene scintillation fluid and counted for 10 min. Radioactivity was extracted from feces (25- to 30-mg samples), mixed with 1 ml 10% methanol to form a slurry, mixed for an additional 19 h on a shaker at medium speed, and centrifuged at 2000 X g for 20 min. A 500-pl aliquot of supernatant was removed from each tube, transferred to a scintillation vial, and counted on the LSC. Cheap Diskus Advair
Compartmental pharmacokinetic analysis was carried out on experimental data from [14C]testosterone-treated mice. Data of the rates of excretion vs. time were fitted with WinNonlin (Scientific Consulting Inc., Apex, NC), a pharmacokinetics computer program, using the formulae for the pharmacokinetic parameters as described by Gibaldi and Perrier. All rates were calculated from the radioactivity measured and did not take into account the metabolic state of the testosterone.