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Vanadate action on renal phosphate transport
A N Sanghvi1, D K Steenbergen, S A Seifert
1Department of Physiology and Biophysics, Indiana University School of Medicine, Indianapolis 46202-5120.
Summary
Vanadate stimulates phosphate reabsorption in healthy rats, but not in diabetic rats. Unlike insulin, vanadate did not effectively reduce phosphate excretion in diabetic models.
Area of Science:
- Nephrology
- Endocrinology
- Mineral Metabolism
Background:
- Insulin is known to promote phosphate reabsorption in the renal proximal tubule.
- Vanadate has demonstrated insulin-mimetic effects in various tissues.
- The impact of vanadate on renal phosphate transport in diabetes is not well understood.
Purpose of the Study:
- To investigate the effect of vanadate on renal phosphate (Pi) transport in both control and streptozotocin-induced diabetic rats.
- To compare the effects of vanadate with insulin on phosphate excretion in diabetic rats.
Main Methods:
- Vanadate was administered orally to control and diabetic rats for four days.
- Urinary phosphate excretion, plasma glucose, and acid-base status were measured.
- Renal brush border membrane vesicles were used to assess Na+/Pi cotransport.
Main Results:
- In control rats, vanadate significantly reduced urinary phosphate excretion without altering plasma glucose or filtered phosphate load.
- In diabetic rats, vanadate partially reversed diabetes-related symptoms but did not significantly decrease urinary phosphate excretion.
- Insulin treatment in diabetic rats significantly reduced urinary phosphate excretion, unlike vanadate.
Conclusions:
- Vanadate stimulates tubular phosphate reabsorption in normal rats.
- Vanadate's effect on tubular phosphate reabsorption is impaired in diabetic rats.
- Vanadate treatment in diabetes may have different effects on tubular phosphate reabsorption compared to insulin.