Related Experiment Videos
Renal brush-border membrane Na(+)-sulfate cotransport: stimulation by thyroid hormone
H S Tenenhouse1, J Lee, N Harvey
1Department of Pediatrics, McGill University-Montreal Children's Hospital Research Institute, Quebec, Canada.
The American Journal of Physiology
|September 1, 1991
Summary
Phosphonoformic acid (PFA) competitively inhibits Na(+)-sulfate cotransport. Thyroid hormone (T3) stimulates Na(+)-dependent sulfate and phosphate transport but does not affect PFA binding.
Area of Science:
- Nephrology
- Molecular Biology
- Endocrinology
Background:
- The Na(+)-sulfate cotransporter plays a crucial role in renal reabsorption.
- Thyroid hormones influence various physiological processes, including ion transport.
- Understanding interactions with inhibitors like phosphonoformic acid is key to elucidating transporter function.
Purpose of the Study:
- To investigate the interaction of phosphonoformic acid (PFA) with the Na(+)-sulfate cotransporter.
- To determine the effect of triiodothyronine (T3) on Na(+)-dependent sulfate transport and PFA binding in mouse renal brush-border membranes.
Main Methods:
- Utilized mouse renal brush-border membrane vesicles.
- Performed kinetic studies to analyze transport inhibition and stimulation.
- Assessed Na(+)-dependent PFA binding and displacement assays.
Main Results:
- PFA competitively inhibits Na(+)-dependent sulfate transport (Ki = 4.3 ± 1.1 mM).
- Pharmacological doses of T3 significantly stimulate Na(+)-dependent sulfate and phosphate transport by increasing Vmax.
- T3 did not affect Na(+)-dependent PFA binding or sulfate/phosphate-displaceable PFA binding.
- Na(+)-sulfate cotransport remained unchanged in phosphate-deprived or X-linked Hyp mice.
Conclusions:
- PFA is a competitive inhibitor of Na(+)-sulfate cotransport.
- T3 stimulates Na(+)-dependent sulfate and phosphate transport, independent of PFA binding.
- Na(+)-sulfate cotransport is not influenced by phosphate homeostasis or the X-linked Hyp mutation.