Parathyroidectomized , rats

Increasing the level of phosphorus intake has long been known to exert a hypocalciuretic effect (22,23). Bell et al. (24) suggested that this effect may be secondary to an increase in PTH secretion, but phosphorus supplementation has been reported to decrease urinary calcium even in parathyroidectomized rats (14). Goldsmith and coworkers (25) found phosphate supplements to cause an increase in PTH... 

Gudmundsson et al. (G4) found that thyrocalcitonin produced no fall in calcium in parathyroidectomized rats, although the hypophosphatemic response was still present. If, however, the parathyroidectomized rats were previously fed a diet high in calcium and low in phosphate, so that... 

The kidney is obviously a possible site of action of thyrocalcitonin increased output of calcium in the urine might well account for the rapid fall in plasma calcium levels. Kenny and Heiskell (Kl), however, found that thyrocalcitonin produced an increased excretion of phosphate in the rat, but no significant effect on urinary calcium or creatinine output. Milhaud and Moukhtar (M9) obtained similar results in thyro-parathyroidectomized rats, although Stahl et al. (S3) found that the increased ratio of phosphate to creatinine in the urine of intact animals treated with thyrocalcitonin did not occur if there had been prior thyro-parathyroidectomy. 

Parathyroid hormone can be assayed by its phosphaturic effect in mice (D2), its calcemic effect in parathyroidectomized rats (Dl, Mil), its effect on serum calcium in the dog (Ul), and its effect on the excretion of isotopic calcium or phosphate in the urine after the labeling of rats with Ca or P (C8, C9). None of these methods is particularly sensitive, and for this reason little work has been done on the estimation of parathyroid hormone in biological fluids. An attempt has been made to meas-... 

Russell RGG, Miihlbauer RC, Bisaz S et al (1970) The influence of pyrophosphate, condensed phosphates, phosphonates and other phosphate compounds on the dissolution of hydroxyapatite in vitro and on bone resorption induced by parathyroid hormone in tissue culture and in thyro-parathyroidectomized rats. Calcif Tissue Res 6 183-196 Saha GB, Boyd CM (1978) Plasma protein-binding of " Tc-pyrophosphate. Int. J Nucl Med Biol 5 236-239... 

The experiment design was to compare the calciuric response to arginine infusion in parathyroidectomized (PTX) and sham-operated (control) rats (25). Four experimental groups were used PTX infused with saline or arginine (12 mmol/kg/hour), and sham-operated... 

The first indication that the thyroid gland was involved in the control of hypercalcemia arose during parathyroidectomy studies in the rat by Hirsch et al. (H3). The mean plasma calcium level of groups of rats parathyroidectomized by hot-wire cautery was much lower 5 hours after operation than was the case in similar animals parathyroidectomized by surgical excision (5.7 and 8.1 mg/100 ml, respectively.) Further, the plasma calcium level of rats parathyroidectomized by excision could be... 

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