Partitioning of regulatory sites in Bufo marinus during hypercapnia.

Ureters were cannulated in specimens of Bufo marinus (L.) in order to partition the regulatory contributions of the kidney and skin. The in vivo roles of the kidney, skin and internal calcareous deposits in the response of these animals to chronic hypercapnia were then evaluated. There was no compensatory adjustment by the skin and only a minimal regulatory response by the kidney. Major adjustments which have been attributed to combined skin and urinary tract in previous studies must therefore come from the urinary bladder. Removal of the bladder as a regulatory site in these animals completely eliminated the compensatory elevation of HCO3- in the extracellular fluid. Mobilization of internal calcareous deposits as a source of HCO3- was found to contribute 50% of the compensatory response of these animals during hypercapnia.