The Blood Calcium Response of the Chicken to Parathyroid Extracts1

Polin, D.; Sturkie, Paul D.; Hunsaker, W. G.

doi:10.1210/endo-60-1-1

Cited by 31 publications

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“…First reported in chickens by Polin, Sturkie & Hunsaker (1957), this response has been confirmed in several laboratories (Candlish & Taylor, 1970;Lewis & Taylor, Immature, 2-to 4-week-old Japanese quail (Coturnix coturnix japónica) of both sexes, were selected from a colony bred and maintained at the Dalton Research Center. The birds were fed a commercial diet (Purina Game Bird Startena), containing 1-2 % calcium, until the start of the experiment and kept in rooms with a 14 h light : 10 h darkness cycle (lights on from 05.00 to 19.00 h) from the time of hatching.…”

Section: Introductionmentioning

confidence: 72%

The Hypercalcaemic Response to Parathyroid Hormone in Japanese Quail

Kenny¹,

Dacke²

1974

Journal of Endocrinology

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SUMMARY The nature of the rapid hypercalcaemic response in birds to intravenously administered parathyroid hormone (PTH) has been studied using the Japanese quail and, to a lesser extent, the chicken. The response has been examined in acutely 45Ca-labelled birds. Parathyroid hormone, synthetic (Beckman 1–34 peptide) bovine PTH, was given with or without the simultaneous administration of a calcium load of 51 mm-CaCl2. It is concluded that the hypercalcaemic response in birds is complex involving two or more underlying mechanisms. The initial phase (30 min or less) is characterized by an increase in plasma 45Ca levels; interpretation of this response in terms solely of bone resorption is difficult. It is suggested that inhibition of bone accretion is the basis for the initial phase. The later phase (30 min or longer) can be interpreted as being largely due to bone resorption. In calciumloaded birds, which were used in recently described avian bioassay methods for PTH, similar results, and therefore interpretations, pertain. No immediate hypocalcaemic response to PTH was found in immature Japanese quail or chickens.

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Section: Introductionmentioning

confidence: 72%

The Hypercalcaemic Response to Parathyroid Hormone in Japanese Quail

Kenny¹,

Dacke²

1974

Journal of Endocrinology

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“…Chicks were chosen as experimental models because their diet can be controlled immediately after hatching, permitting the rapid development of magnesium depletion. In addition, chickens are known to be sensitive to parathyroid extract (15), thus providing a suitable model to evaluate responsiveness to the hormone. Furthermore, considerable information is available concerning calcium homeostasis in this species.…”

Section: Introductionmentioning

confidence: 99%

Studies on Mechanisms of Hypocalcemia of Magnesium Depletion

Reddy¹,

Coburn²,

Hartenbower³

et al. 1973

J. Clin. Invest.

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A B S T R A C T Studies were carried out to evaluate the mechanism of hypocalcemia in magnesium depletion. Day old chicks fed a magnesium deficient diet developed marked hypocalcemia, with a direct relation between serum calcium (y) and magnesium (x): y = 2.68 x + 4.24, r = 0.84 (both in mg/100 ml). Injections of parathyroid extract that increased serum calcium 2-3 mg/100 ml in normals had no effect in Mg-depleted birds. Very large dietary supplements of calcium or vitamin D3 increased mean serum calcium only from 5.3 to 7.7 and 7.8 mg/100 ml, respectively, while a normal magnesium diet for 3 days increased calcium from 5.3 to 9.9 mg/100 ml despite absence of dietary calcium. Intestinal calcium transport, studied in vitro, and the calcium concentration of the carcass was significantly increased in magnesium-depleted chicks, making it unlikely that reduced intestinal absorption of calcium caused the hypocalcemia. In magnesium-deficient chicks, the bone content of magnesium was decreased by 74%, the calcium content was unchanged, and the cortical thickness of bone was markedly increased. After 3 days of magnesium-repletion, cortical thickness was reduced with increased endosteal resorption. There INTRODUCTIONHypocalcemia has been reported to be associated with magnesium depletion in a number of species, including rats fed a low calcium diet (1, 2), sheep (3), pigs (4), calves (5, 6), dogs (7,8), monkeys (9), and man (10)(11)(12)(13)(14) In the present study, a model of experimental magnesium depletion in the chick is described, and various factors which might be involved in the development of hypocalcemia were evaluated. METHODS White leghorn cockerels obtained 1 day after hatching (through courtesy of H & N Hatchery, Inc., Riverside, Calif.) were housed in electric brooders. Chicks were chosen as experimental models because their diet can be controlled immediately after hatching, permitting the rapid development of magnesium depletion. In addition, chickens are known to be sensitive to parathyroid extract (15), thus providing a suitable model to evaluate responsiveness to the hormone. Furthermore, considerable information is available concerning calcium homeostasis in this species.They received a synthetic diet, modified from that of Fox and Briggs (16), and distilled water ad libitum. The diet, as originally described, contained 0.060% magnesium, an amount considered the optimal quantity needed by growing chicks (16,17). With deletion of supplemental magnesium and calcium salts, the basic diet was found by analysis to contain 0.004% magnesium and 0.005% calcium. In preparation of certain diets discussed below, magnesium sulfate was added providing 0.010, 0.020, or 0.060% magnesium.Unless noted otherwise, the diets were supplemented to contain 1.2% calcium, an amount higher than the 0.7-0.8% usually provided, 0.8% phosphorus, and 80 IU of vitamin D3 (cholecalciferol) /100 g.For purposes of establishing the appropriate dietary magnesium for studying magnesium depletion in the fowl, preliminary experiments were ...

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“…One reason may be that a number of early investigators, cited by Polin et al (3), were unable to detect any effect of PTH on blood calcium in birds. More recent studies have shown that these negative results were probably due to failure to examine calcium levels early enough (3,4). It has been reported (4) that laying hens exhibit significant hypercalcemia 8 min after iv injection of 20 U/kg PTH and a similarly rapid response has been reported for chicks and Japanese quail (5).…”

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confidence: 99%

Plasma Calcium and Inorganic Phosphate Response of Laying Hens to Parathyroid Hormone1

et al. 1973

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The plasma calcium and phosphate response to iv injection of PTH was studied in laying hens fed diets containing 2.26% or 5.00% calcium, both during periods of egg shell formation and when no egg was in the shell gland. Compared with results for mammals, the response was considerably larger, more rapid and more transient. With PTH injection at 0 min, plasma calcium (5.00% calcium diet only) and phosphate were significantly decreased at 5 min. This was followed by an increase in the concentration of both ions until a maximum was reached between 20 and 30 min. After 60 min, plasma levels of pullets fed the 2.26% calcium diet were again practically normal. The maximum plasma calcium and phosphate response for the 5.00% calcium diet was more than twice as large as for the 2.26% calcium diet, while the stage in the egg cycle had no effect on the response curves. During the period of hypercalcemia the increases in plasma calcium and phosphate were closely correlated (r = 0.733, p < 0.001), suggesting that the release of these two ions into blood was caused by a common mechanism. The rapid decay of the PTH response and its dependence on dietary calcium may explain the results of some investigators who found little or no response to parathyroid hormone in laying hens. (Endocrinology 92: 853, 1973) D URING the formation of each egg shell laying hens fed a diet containing 1.95% calcium mobilize about 4% of their skeletal calcium (1). Although it is likely that parathyroid hormone (PTH) plays a role in synchronizing egg formation and the concomitant changes in skeletal metabolism (2) surprisingly little is known about the effects of PTH in laying hens. One reason may be that a number of early investigators, cited by Polin et al. (3), were unable to detect any effect of PTH on blood calcium in birds. More recent studies have shown that these negative results were probably due to failure to examine calcium levels early enough (3, 4). It has been reported (4) that laying hens exhibit significant hypercalcemia 8 min after iv injection of 20 U/kg PTH and a similarly rapid response has been reported for chicks and Japanese quail (5).Information of the phosphatemic response

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The Blood Calcium Response of the Chicken to Parathyroid Extracts1

Cited by 31 publications

References 0 publications

The Hypercalcaemic Response to Parathyroid Hormone in Japanese Quail

The Hypercalcaemic Response to Parathyroid Hormone in Japanese Quail

Studies on Mechanisms of Hypocalcemia of Magnesium Depletion

Plasma Calcium and Inorganic Phosphate Response of Laying Hens to Parathyroid Hormone1

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