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Biomedical subjects

R C Puche

Publications and source records attributed to R C Puche.

At least 55 records · Page 3Linked to original sources
PubMed1985

Genetic conditioning of the response of rat bone tissue to estradiol.

The effects of the administration of pharmacological doses of estradiol were studied in two genetically different lines of inbred rats, at two stages of development, to gain a new insight into the genetic and physiological organization of the response of bone and Ca metabolism to exogenous estrogens. The comparative analysis of the effects on bone tissue revealed that the pattern of cellular activities at bone surfaces, the increased trabecular bone volume and the increased calcium accretion are separate responses. Likewise, the closure of the epiphyseal plate may not be associated with the curtailment of body weight increase. In addition, only one of the lines increased its intestinal calcium absorption. It appears evident that the response to exogenous estradiol relies upon the action of more than one locus. The simultaneous occurrence of partial responses (successful treatment) depends upon as yet undefined genetic and environmental (endocrine, nutritional, etc.) conditions. Extension of these conclusions to the human being implicates the recognition that a fraction of the patients undergoing estrogenic treatment may be insensitive to therapy.

Animals↗
PubMed1985

Calcium metabolism of intact and thyroparathyroidectomized rats fed a bicarbonate enriched diet.

Rats fed a bicarbonate-enriched diet become alkalotic during their feeding period (ca. 10 h/day). Alkalosis produced a significant reduction in the plasmatic concentration of ionized calcium and increased parathyroid hormone secretion confirmed by concurrent hypophosphatemia and increased urinary excretion of cAMP. Three weeks of treatment produced, however, a significant reduction of bone Ca resorption. The increased endogenous fecal excretion of calcium counteracted the enhancement of true calcium absorption. No significant change in the skeletal calcium mass was observed. Thyroparathyroidectomized rats fed the alkaline diet reduced further their rate of bone Ca resorption and increased significantly their skeletal calcium mass.

Absorption↗
PubMed1985

The urinary excretion of ionized and non-ionized calcium by rats treated with 1.25-dihydroxycholecalciferol.

The administration of 1,25-dihydroxycholecalciferol to rats increased their calciuresis as a power function of the dose. Up to 95% of the urinary calcium was excreted as a non-ionized complex, together with equimolar amounts of citrate. The stoichiometry between calcium and citrate, observed at all dose levels, suggests that citrate metabolism is coordinated with the mobilization of calcium.

Animals↗
PubMed1985

The effect of alkalosis on the glucose-mediated insulin release by the rat.

Bicarbonate loaded (alkalotic) rats had reduced plasma phosphate and ionized Ca concentrations and increased urinary cAMP excretion, phosphate clearance and pancreatic tissue uptake of extracellular calcium, all known effects of increased parathyroid hormone (PTH) secretion. Total insulin secretion after glucose challenge was enhanced in these animals. The response of alkalotic thyroparathyroidectomized rats, on the other hand, suggested exhaustion or inhibition of insulin secretion. The hypothesis is advanced that PTH, enhancing the permeability to calcium of the beta-cell membrane, compensated the effect of decreased calcium concentration in the extracellular fluid caused by alkalosis. PTH appears instrumental for homeostatic adjustments of insulin secretion.

Alkalosis↗
PubMed1984

Respiratory alkalosis and reduced plasmatic concentration of ionized calcium in rats treated with 1,25 dihydroxycholecalciferol.

The daily administration of supraphysiological doses of 1,25 dihydroxycholecalciferol (0.1-2.5 micrograms/d/100 g body weight) to rats, produced respiratory alkalosis. With the doses of 0.1-0.2 micrograms/d/100 g and feeding a diet with 0.7% of calcium, calcemias did not exceed 2.75 mM, and significantly reduced plasma ionized calcium levels were measured. The latter phenomenon was found associated with increased urinary excretion of cAMP, soft tissue calcium content, and polyuria with hypostenuria, all known effects of parathyroid hormone. These effects were absent in thyroparathyroidectomized rats treated in the same fashion. Present results suggest that the stimulus of low levels of plasma ionized calcium overcomes the probably inhibitory effect of the steroid on parathyroid hormone secretion.

Alkalosis, Respiratory↗
PubMed1983

Non uniform effect of estradiol on the rat skeleton.

Pharmacological doses of estradiol administered to rats increased the Ca mass of their femurs through a significant reduction in the rate of Ca resorption. On a body basis, the same animals showed increased rates of skeletal Ca deposition and resorption and no effect on the skeletal mass. The non uniform effect of estradiol on the skeleton, if confirmed in the human being, may limit the applicability of estrogenic treatment.

Animals↗
PubMed1980

Effect of 1,25-dihydroxycholecalciferol and 1,25-dihydroxycholecalciferol glycoside on 2,3-diphosphoglycerate levels of the rat erythrocyte.

The erythrocytes of rats treated with 1, 25-dihydroxycholecalciferol or 1, 25-dihydroxycholecalciferol glycoside showed decreased levels of 2, 3-diphosphoglycerate. The same result has been obtained in vitro, indicating a direct effect of the sterol on the red cell. The glycoside is less active than the free sterol in vivo and more active in vitro. The decreased levels of diphosphoglycerate induced tissue hypoxia as shown by a higher plasma lactate/pyruvate ratio and a three fold increase in plasma erythropoietin concentration.

Animals↗
PubMed1978

On the nature of arterial and lung calcifications induced in cattle by Solanum glaucophyllum.

The chemical and crystalline composition of the mineral deposited in ossified arterial and lung tissues of cows affected by enteque seco (enteque ossificans) has been investigated. The arterial calcification precedes that of lung. The latter was observed only in animals with a calcification of the aorta above 150 mumoles Ca per gram of wet tissue. The mineral deposited in arterial and lung tissues appeared to be a poorly crystallized apatite; following incineration the diffraction patterns of carbonate apatite and magnesium whitlockite, respectively, were found.

Animals↗
PubMed1976

Effect of bicarbonate feeding on immobilization osteoporosis in the rat.

A time course study of immobilization osteoporosis was carried out in an experimental model in which the hind half of the rat was paralyzed by spinal section between the 3rd and 4th lumbar vertebrae. The earliest changes in the femure were a reduction in water content and in bone volume (3 days after operation). A significant reduction in both hydroxyproline and phosphate content was observed 8 days after immobilization. Calcium, magnesium, sodium, citrate, and carbonate were found significantly decreased at 15 days. Bone potassium remained unchanged. The rate of calcium accretion and the size of the exchangeable pools, when expressed per unit of bone mass, were not significantly affected by treatment. Sham-operated rats fed a bicarbonate-enriched diet, showed increased rates of calcium accretion and bone calcium content. The latter was not accompanied by increases in phosphate and carbonate contents. Operated animals fed the same diet showed an increased rate of bone resorption attributed to an assumed higher rate of parathyroid hormone secretion induced by bicarbonate feeding.

Animals↗
PubMed1976

The effects of long term feeding of Solanum glaucophyllum to growing rats on Ca, Mg, P and bone metabolism.

The effects of the long term ingestion of Solanum Glaucophyllum leaves (SG) by the rat was investigated in two series of experiments; the animals were fed a normal (for 8 weeks) or a low Ca diet (for 5 weeks). With both diets, the intestinal absorption of Ca was increased and the endogenous fecal Ca excretion was decreased by SG treatment. Added to a normal Ca diet, SG increased the urinary excretion of Ca, Mg and P and reduced the excretion of hydroxyproline and pyrophosphate. At the histological level, SG induced a higher rate of bone tissue synthesis on trabecular and endosteal surfaces. The bone content of hydroxyproline and citrate increased significantly. The total alkaline phosphatase activity of plasma decreased as a function of SG intake due to a decreased in the activity of the intestinal isoenzyme, which was not compensated by the increase in the bone isoenzyme activity. The Mg absorption was decreased by SG inducing lower Mg balances and lower plasma Mg levels. Added to a low Ca diet, SG increased the severity of the secondary hyperparathyroidism induced by the diet. The urinary excretion of hydroxyproline and the plasma alkaline phosphatase activity (both isoenzymes) were significantly increased. The Na and K content of bone decreased as a function of SG intake. 45Ca kinetic experiments revealed that SG increased the rate of Ca resorption and the rate constant of the fast exchangeable Ca pool, in both diets.

Alkaline Phosphatase↗