Organ distribution of exogenous 14C-urea in elasmobranchs, with special regard to the nervous system

Abstract

1. 1. Body fluid and selected tissue distributions of exogenous, intravenously administered 14C-urea were studied in two elasmobranch species, Negaprion brevirostris and Squalus acanthias. 2. 2. Patterns of distribution were similar in the two species for equivalent time periods. Blood, cerebrospinal fluid (CSF) and kidney 14C-urea concentrations were high with similar patterns. Other body tissue levels, including the brain and extradural fluid (EDF), were only one-half to one-tenth the levels of blood, CSF and kidney. 3. 3. Quantitatively, species differences in 14C-urea concentrations were observed between N. brevirostris and S. acanthias. In general, 14C-urea tissue levels were higher in N. brevirostris than S. acanthias. 4. 4. In addition to the species variation, the distribution of 14C-urea differed in S. acanthias held at different temperatures and salinities. Brain and kidney values tended to be initially lower, and subsequently higher with increasing temperatures and salinities with time. 5. 5. In sharks a high CSF and low EDF distribution was observed.