ABSTRACT
The toad Bufo viridis can be acclimated to high salt solutions up to 800 mosmol kg−1 of NaCl (Tercafs & Schoffeniels, 1962; Katz, 1973). Despite extensive studies on various aspects of adaptation to high salt in this species (Gordon, 1962; Katz, 1979; Katz, Garcia-Romeu, Masoni & Isaia, 1981) only little attention has been paid to the osmoregulatory roles of the kidneys and urinary bladder during high salt acclimation. In/tana cancrivora, a species which can be acclimated to salinities even higher than B. viridis (and which shares the property of urea accumulation) Schmidt-Nielsen & Lee (1962), found a lower urine flow under high salt and consequently reduced urea secretion, while Gordon & Tucker (1968) observed urea retention at first, but increasing loss at salinities higher than 400 mosmol kg−1. Ferreira & Jesus (1973), presented evidence in salt adapted B. bufo suggesting increased osmolarity (mainly sodium) in the urinary bladder. We therefore attempted to assess the turnover of water and urea in B. viridis with special emphasis on the contribution of the renal and the urinary bladder.
