Mature male spiny dogfish sharks (Squalus acanthias; 1.06-2.18 kg; 36- to 49-cm snout-vent length) were collected from the Gulf of Maine through the facilities of the Mount Desert Island Biological Laboratory (Salsbury Cove, ME) during the period of spermatogenic activity (June-October) and were kept in running-seawater tanks no longer than 2 wk. Animals were killed by double pithing via the olfactory canal. Protocols for the care and use of animals were approved by the Mount Desert Island Biological Laboratory Institutional Animal Care and Use Committee. buy birth control online
Tissue 109Cd Concentrations and Organ Distribution
Animals (3 per treatment group) were injected with 109CdCl2 (specific activity 3.19 mCi/mg; New England Nuclear, Boston, MA; 2.84 ^Ci/0.3 ml water per animal) via the caudal vein. The estimated dose (2 ^Ci/kg) was based on a mean projected body weight of 1.4 kg. To determine blood and plasma elimination, one group was used for collection of sequential samples (1 ml) from the caudal vein into heparinized syringes 1, 3, 6, 12, and 24 h after tracer injection and then killed to determine tissue 109Cd levels. Additional blood and tissue samples were taken from animal groups killed 3 or 7 days after tracer injection alone (control) and 3 or 7 days after a single injection of radio-inert CdCl2 (5 mg/0.2 ml water per kilogram body weight) followed by an injection of tracer 24 h before death (Cd pretreated). The dose of CdCl2 chosen is within the effective range for spermatotoxicity in rodents (1-8 mg/kg; ). All tissues were kept at 4°C during processing, and triplicate samples were taken for analysis. Whole blood and plasma were analyzed separately. Organ weights were determined for testes (plus epigonal organ), liver, kidney, spleen, heart, rectal gland, and brain.