Parathyroid hormone-like changes in renal calcium and phosphate reabsorption induced by Leydig cell tumor in thyroparathyroidectomized rats

Endocrinology
R RizzoliJ P Bonjour

Abstract

The Leydig cell tumor Rice H-500 is a model of humoral hypercalcemia of malignancy. Hypercalcemia is considered to result mainly from increased bone resorption. However, a change in renal tubular reabsorption of calcium (Ca) as a contributing factor to the hypercalcemia has not yet been recognized. The purpose of this study was to examine whether the renal handling of Ca was altered in Leydig cell tumor-bearing rats. To avoid counterregulations by Ca-regulating hormones, the effect of the Leydig cell tumor on plasma Ca and phosphate (Pi), urinary Ca and Pi excretion, as well as Ca and Pi renal tubular reabsorptive capacity was investigated in thyroparathyroidectomized rats. Clearance experiments were conducted at a time of tumor development when the glomerular filtration rate was not compromised. Under these conditions, tubular reabsorption of Ca was stimulated, and the maximal tubular reabsorption of Pi was markedly reduced (2.69 +/- 0.27 vs. 4.57 +/- 0.21 mumol/min; P less than 0.001). These changes were accompanied by increased urinary cAMP excretion (77.1 +/- 6.3 vs. 34.7 +/- 2.8 pmol/ml glomerular filtrate; P less than 0.001). These results indicate that the Leydig cell tumor produces a factor with PTH-like activity on the...Continue Reading

Citations

Dec 1, 1989·Journal of Bone and Mineral Research : the Official Journal of the American Society for Bone and Mineral Research·R Rizzoli, J P Bonjour
Jun 1, 1990·Journal of Bone and Mineral Research : the Official Journal of the American Society for Bone and Mineral Research·S J ScheinmanA F Stewart
Dec 1, 1993·Pediatric Nephrology : Journal of the International Pediatric Nephrology Association·F LawJ P Bonjour
Jan 1, 1990·Calcified Tissue International·D J Hosking
Aug 1, 1996·Hematology/oncology Clinics of North America·Y M Barri, J P Knochel
Sep 15, 1990·International Journal of Cancer. Journal International Du Cancer·R RizzoliJ P Bonjour
Jan 1, 1987·Kidney International·G R Mundy
Jan 1, 1988·Domestic Animal Endocrinology·T J Rosol, C C Capen
Oct 1, 1989·Journal of Bone and Mineral Research : the Official Journal of the American Society for Bone and Mineral Research·R RizzoliJ P Bonjour
Feb 1, 1989·Journal of Bone and Mineral Research : the Official Journal of the American Society for Bone and Mineral Research·S H RalstonI T Boyle
Oct 1, 1988·Journal of Bone and Mineral Research : the Official Journal of the American Society for Bone and Mineral Research·P J ShipleyS C Kukreja
Apr 1, 1988·Journal of Bone and Mineral Research : the Official Journal of the American Society for Bone and Mineral Research·L PizurkiJ P Bonjour
Sep 1, 1988·The New England Journal of Medicine·A E BroadusA F Stewart
Nov 9, 2005·American Journal of Physiology. Renal Physiology·Theresa J BerndtRajiv Kumar
Mar 12, 1998·Endocrine Reviews·H Fleisch

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