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Title: Calcium transport in turtle bladder

Abstract

Unidirectional {sup 45}Ca fluxes were measured in the turtle bladder under open-circuit and short-circuit conditions. In the open-circuited state net calcium flux (J{sup net}{sub Ca}) was secretory (serosa to mucosa). Ouabain reversed J{sup net}{sub Ca} to an absorptive flux. Amiloride reduced both fluxes such that J{sup net}{sub Ca} was not significantly different from zero. Removal of mucosal sodium caused net calcium absorption; removal of serosal sodium caused calcium secretion. When bladders were short circuited, J{sup net}{sub Ca} decreased to approximately one-third of control value but remained secretory. When ouabain was added under short-circuit conditions, J{sup net}{sub Ca} was similar in magnitude and direction to ouabain under open-circuited conditions (i.e., absorptive). Tissue {sup 45}Ca content was {approx equal}30-fold lower when the isotope was placed in the mucosal bath, suggesting that the apical membrane is the resistance barrier to calcium transport. The results obtained in this study are best explained by postulating a Ca{sup 2+}-ATPase on the serosa of the turtle bladder epithelium and a sodium-calcium antiporter on the mucosa. In this model, the energy for calcium movement would be supplied, in large part, by the Na{sup +}-K{sup +}-ATPase. By increasing cell sodium, ouabain would decrease the activity of the mucosal sodium-calciummore » exchanger (or reverse it), uncovering active calcium transport across the serosa.« less

Authors:
;  [1]
  1. Texas Tech Univ. Health Sciences Center, Lubbock (USA)
Publication Date:
OSTI Identifier:
7027236
Resource Type:
Journal Article
Journal Name:
American Journal of Physiology; (USA)
Additional Journal Information:
Journal Volume: 253:6; Journal ID: ISSN 0002-9513
Country of Publication:
United States
Language:
English
Subject:
59 BASIC BIOLOGICAL SCIENCES; CALCIUM 45; MEMBRANE TRANSPORT; MEMBRANE PROTEINS; BIOCHEMISTRY; ATP-ASE; BLADDER; CALCIUM CHLORIDES; DIURETICS; MUCOUS MEMBRANES; OUABAIN; SODIUM CHLORIDES; TURTLES; ACID ANHYDRASES; ALKALI METAL COMPOUNDS; ALKALINE EARTH ISOTOPES; ALKALINE EARTH METAL COMPOUNDS; ANIMALS; BETA DECAY RADIOISOTOPES; BETA-MINUS DECAY RADIOISOTOPES; BODY; CALCIUM COMPOUNDS; CALCIUM HALIDES; CALCIUM ISOTOPES; CARBOHYDRATES; CARDIAC GLYCOSIDES; CARDIOTONICS; CARDIOVASCULAR AGENTS; CHEMISTRY; CHLORIDES; CHLORINE COMPOUNDS; DAYS LIVING RADIOISOTOPES; DRUGS; ENZYMES; EVEN-ODD NUCLEI; GLYCOSIDES; HALIDES; HALOGEN COMPOUNDS; HYDROLASES; INTERMEDIATE MASS NUCLEI; ISOTOPES; MEMBRANES; NUCLEI; ORGANIC COMPOUNDS; ORGANS; PHOSPHOHYDROLASES; PROTEINS; RADIOISOTOPES; REPTILES; SODIUM COMPOUNDS; STROPHANTHINS; URINARY TRACT; VERTEBRATES; 550201* - Biochemistry- Tracer Techniques

Citation Formats

Sabatini, S, and Kurtzman, N A. Calcium transport in turtle bladder. United States: N. p., 1987. Web.
Sabatini, S, & Kurtzman, N A. Calcium transport in turtle bladder. United States.
Sabatini, S, and Kurtzman, N A. 1987. "Calcium transport in turtle bladder". United States.
@article{osti_7027236,
title = {Calcium transport in turtle bladder},
author = {Sabatini, S and Kurtzman, N A},
abstractNote = {Unidirectional {sup 45}Ca fluxes were measured in the turtle bladder under open-circuit and short-circuit conditions. In the open-circuited state net calcium flux (J{sup net}{sub Ca}) was secretory (serosa to mucosa). Ouabain reversed J{sup net}{sub Ca} to an absorptive flux. Amiloride reduced both fluxes such that J{sup net}{sub Ca} was not significantly different from zero. Removal of mucosal sodium caused net calcium absorption; removal of serosal sodium caused calcium secretion. When bladders were short circuited, J{sup net}{sub Ca} decreased to approximately one-third of control value but remained secretory. When ouabain was added under short-circuit conditions, J{sup net}{sub Ca} was similar in magnitude and direction to ouabain under open-circuited conditions (i.e., absorptive). Tissue {sup 45}Ca content was {approx equal}30-fold lower when the isotope was placed in the mucosal bath, suggesting that the apical membrane is the resistance barrier to calcium transport. The results obtained in this study are best explained by postulating a Ca{sup 2+}-ATPase on the serosa of the turtle bladder epithelium and a sodium-calcium antiporter on the mucosa. In this model, the energy for calcium movement would be supplied, in large part, by the Na{sup +}-K{sup +}-ATPase. By increasing cell sodium, ouabain would decrease the activity of the mucosal sodium-calcium exchanger (or reverse it), uncovering active calcium transport across the serosa.},
doi = {},
url = {https://www.osti.gov/biblio/7027236}, journal = {American Journal of Physiology; (USA)},
issn = {0002-9513},
number = ,
volume = 253:6,
place = {United States},
year = {Tue Dec 01 00:00:00 EST 1987},
month = {Tue Dec 01 00:00:00 EST 1987}
}