Calcium transport in turtle bladder

Journal Article · Tue Dec 01 00:00:00 EST 1987 · American Journal of Physiology; (USA)

OSTI ID:7027236

Sabatini, S; Kurtzman, N A ^[1]

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1. Texas Tech Univ. Health Sciences Center, Lubbock (USA)

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.

• OSTI ID: 7027236
• Journal Information: American Journal of Physiology; (USA), Vol. 253:6; ISSN 0002-9513
• Country of Publication: United States
• Language: English

Related Subjects

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