Medullary structures in calcium reabsorption in rats with renal insufficiency
Finkelstein, F.O.; Kliger, A.S.
American Journal of Physiology 233(3): F197-F200
1977
ISSN/ISBN: 0002-9513 PMID: 910913 Document Number: 122709
Ca excretion rates were compared in rats nephrectomized 65% and in rats with 1 kidney and the papilla of the remaining kidney removed during hydropenic clearance periods and in response to 3% saline loading and parathyroidectomy. Surgical ablation resulted in a similar reduction in inulin clearance in both groups of experimental animals to about 1/3 of that found in control rats. During base-line hydropenic conditions, Ca and Na excretion rates were similar in both groups of ablated animals. In response to saline loading the papillectomized rats excreted 0.55 .+-. 0.09 .mu.g/min per 100 g body wt of Ca compared to 0.22 .+-. 0.04 .mu.g/min per 100 g body wt in the nephrectomized animals (P < 0.01). Inulin clearance, Na excretion rate, fractional phosphate excretion and serum Ca level were not significantly different in the 2 groups of ablated animals. After thyroparathyroidectomy, the Ca excretion rate in the papillectomized animals during hydropenic conditions increased to 1.60 .+-. 0.41 .mu.g/min per 100 g body wt, a value significantly greater than in the nephrectomized rats, 0.58 .+-. 0.12 .mu.g/min per 100 g body wt (P < 0.05). Inulin clearance, Na excretion rate, fractional phosphate excretion and serum Ca level were again not significantly different in the 2 groups. Medullary structures played a critical role in modulating Ca reabsorption in the rat with renal insufficiency.