Effect of parathyroid hormone on transport by toad and turtle bladder
The authors recently demonstrated that parathyroid hormone (PTH) inhibited both vasopressin- and cyclic AMP-stimulated water transport in the toad bladder. This was associated with an increase in calcium uptake by isolated epithelial cells. They postulated that PTH exerts its action on H/sub 2/O transport by directly stimulating calcium uptake. The current study was designed to compare the effects of PTH and the calcium ionophore, A23187, on H/sub 2/O and Na transport and H..mu.. secretion in toad and turtle bladders. In toad bladder, PTH and A23187 decreased arginine vasopressin (AVP)-stimulated H/sub 2/O flow and short-circuit current (SCC) after 60 min serosal incubation. In turtle bladder A23187 decreased SCC to 79.3 +/- 3.6% of base line (P < 0.05), and significantly decreased RSCC as well. PTH had no effect on SCC or H/sup +/ secretion in turtle bladders. Both PTH and A23187 increased /sup 45/Ca uptake in toad bladder epithelial cells; only A23187 increased /sup 45/Ca uptake in the turtle bladder. The different action of PTH in these two membranes, compared with that of the calcium ionophore, illustrates the selectivity of PTH on membrane transport. PTH increases calcium uptake and decreases transport only in a hormone-sensitive epithelium, whereas the ionophore works in virtually all living membranes. The mode of action of these two agents to increase calcium uptake is, therefore likely different.
- Research Organization:
- Texas Tech Univ. Health Sciences Center, Lubbock
- OSTI ID:
- 6351849
- Journal Information:
- Am. J. Physiol.; (United States), Vol. 252:1
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
CALCIUM 45
MEMBRANE TRANSPORT
PARATHORMONE
BIOLOGICAL EFFECTS
BLADDER
CALCIUM CHLORIDES
SODIUM CHLORIDES
TOADS
TURTLES
WATER
ALKALI METAL COMPOUNDS
ALKALINE EARTH ISOTOPES
ALKALINE EARTH METAL COMPOUNDS
AMPHIBIANS
ANIMALS
AQUATIC ORGANISMS
BETA DECAY RADIOISOTOPES
BETA-MINUS DECAY RADIOISOTOPES
BODY
CALCIUM COMPOUNDS
CALCIUM HALIDES
CALCIUM ISOTOPES
CHLORIDES
CHLORINE COMPOUNDS
DAYS LIVING RADIOISOTOPES
EVEN-ODD NUCLEI
HALIDES
HALOGEN COMPOUNDS
HORMONES
HYDROGEN COMPOUNDS
INTERMEDIATE MASS NUCLEI
ISOTOPES
NUCLEI
ORGANS
OXYGEN COMPOUNDS
PEPTIDE HORMONES
RADIOISOTOPES
REPTILES
SODIUM COMPOUNDS
URINARY TRACT
VERTEBRATES
551001* - Physiological Systems- Tracer Techniques