Volume regulation in salt-acclimated toad (Bufo viridis): the role of urea and the urinary bladder.
Body water (weight) was studied in the euryhaline toad Bufo viridis during high salt (500 mOsm NaCl) acclimation. Plasma osmolality was greatly increased upon salt acclimation mainly by urea, and was always hyperosmotic to the ambient solution. Water content was regulated quite efficiently in slowly acclimated undisturbed toads. Repeatedly catheterized toads behaved like osmometers when transferred to hyperosmotic solutions. Total urea loss was greatly reduced in salt acclimated toads, suggesting urine was not voided under these conditions. It is concluded that urea accumulation, inhibition of the urine voiding response and the urine in the bladder are the principal factors involved in volume regulation under conditions of salt acclimation.
D000064:Acclimatization; D000818:Animals; D001834:Body Water / Q000032:analysis; D001835:Body Weight; D002025:Bufonidae / Q000502:physiology*; D005260:Female; D008297:Male; D012965:Sodium Chloride / Q000494:pharmacology; D014508:Urea / Q000378:metabolism*; D001743:Urinary Bladder / Q000187:drug effects / Q000502:physiology*
D012965:Sodium Chloride; D014508:Urea