Urea uptake and translocation in toad urinary bladder: The effect of antidiuretic hormone
- 21 Downloads
The uptake of C14-urea into everted and noneverted bladder sacs was compared, over short time periods (up to 2 min), with the transepithelial urea fluxes. This method allowed the study of the time course of urea uptake and distribution, while previously this problem was only studied in steady-state conditions. When mucosal uptake was studied no accumulation of C14-urea inside the tissue was observed, indicating that the mucosal border could be the limiting step. Comparative studies of urea and inulin uptake from the serosal side showed that urea equilibrated with the water epithelial cells in less than 30 sec. This accumulation suggested again that the mucosal border is an effective barrier for urea translocation. The kinetics of the increase in urea permeability induced by antidiuretic hormone was also studied and it was similar (T1/2:4.3 min) to the kinetics of the increase in water permeability induced by the hormone (T1/2:5.6 min). A strong parallelism was also observed between the time course of the increases in water and urea permeabilities induced by medium hypertonicity (T1/2 25 and 26 min, respectively). The values obtained for the permeability coefficientktrans), either at rest or under ADH were similar to those previously reported employing steady-state techniques (28±8 and 432±25 cm·sec−1·10−7, respectively).
KeywordsUrea Antidiuretic Hormone Urinary Bladder Inulin Short Time Period
Unable to display preview. Download preview PDF.
- Bentley, P.J. 1958. The effects of neurohypophysial extracts on water transfer across the wall of the isolated toad urinary bladder of the toadBufo marinus.J. Endocrinol. 17:201Google Scholar
- Bourguet, J. 1967. Cinétique de la pérmeabilisation de la vessie de grenouille par I'ocytocine. Role du 3′–5′ adenosine monophosphate ciclique.Biochim. Biophys. Acta 150:104Google Scholar
- Hays, R.M. 1972. The movement of water across vasopressin-sensitive epithelia.In: Current Topics in Membrane and Transport. F. Bronner and A. Kleinzeller, editors. Vol. 3. p. 339. Academic Press, New YorkGoogle Scholar
- McIver, D.J.L., MacKnight, A.D.C. 1974. Extracellular space in some isolated tissues.J. Physiol. (London) 239:31Google Scholar
- Parisi, M., Gauna, A., Rivas, E. 1976. Water permeability and lipid composition in toad urinary bladder: The influence of temperature.J. Membrane Biol. 26:335Google Scholar
- Parisi, M., Piccinni, Z.F. 1973. The penetration of water into the epithelium of toad urinary bladder and its modification by oxytocin.J. Membrane Biol. 12:227Google Scholar
- Pietras, R.J., Wright, E.M. 1975. The membrane action of antidiuretic hormone (ADH) on toad urinary bladder.J. Membrane Biol. 22:107Google Scholar
- Schmidt-Nielsen, B. (1970). Urea analogues and tubular transport competition.In: Urea and the Kidney. B. Schmidt-Nielsen, editor. P. 252. Excerpta Medica Foundation, AmsterdamGoogle Scholar