Cyclic nucleotides and the rapid inhibitions of bone45Ca uptake in response to bovine parathyroid hormone and 16,16-dimethyl prostaglandin E2 in chicks

Shaw, A. J.; Dacke, C. G.

doi:10.1007/bf02556566

Cited by 13 publications

(2 citation statements)

References 23 publications

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“…In the laying hens, approximately 2.4 g Ca 2+ is required over 18 h to produce a shelled egg of 60 g. In the peak production stage, a hen lays almost one egg every day during a 52-wk period. It was calculated that the t½ for 45 Ca uptake by the chick femur is less than 10 min, while a rabbit, dog, and rat took about 30 min ( Shaw and Dacke, 1989 , Bronner and Stein, 1992 ). Therefore, the throughput of Ca 2+ in hens is much more active than in mammals.…”

Section: Discussionmentioning

confidence: 99%

Improvement of eggshell quality by dietary N-carbamylglutamate supplementation in laying chickens

Yao

Zhou

et al. 2020

Poultry Science

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Egg quality defects seriously reduce the quality grade and increase egg breakage in egg marketing activities. In this study, the effect of N-carbamylglutamate ( NCG ) on eggshell quality was investigated by evaluating calcium absorption and calcification in laying hens. A total of 30 newly hatched female Hy-Line chicks were randomly assigned to the control group (basal diet) and treatment group (basal diet supplemented with 1% NCG). At 25 wk, eggs from each group were obtained to assess egg quality parameters. Blood samples were collected for analysis of mineral, hormone, and amino acids levels at 16 h after laying egg. Uterine tissues were removed and fixed in 4% neutral paraformaldehyde solution or kept in liquid nitrogen for mineral determination, quantitative PCR, and Western blot. Results showed that the egg quality (eggshell thickness, strength and percentage, egg specific gravity, and eggshell effective thickness) was significantly increased while effective thickness of mastoid layer, width of mastoid gap, and mammillary knobs were significantly decreased by dietary NCG supplementation ( P < 0.05). The levels of minerals (Ca, P, Fe, Mg, Na, K) in eggshell, plasma, and uterus were remarkably elevated ( P < 0.05). Meanwhile, the concentrations of calcium metabolism–related hormones (17β-estradiol, parathyroid hormone, and calcitonin) were increased in the NCG group ( P < 0.05). Moreover, expression of calbindin 1, carbonic anhydrase 2, ovalbumin, ovotransferrin, ovocleidin-17, ovocleidin-116, and clusterin mRNAs, as well as calbindin 1 and ATP2A1 proteins in uterus, duodenum, and kidney, was all upregulated in hens fed with NCG ( P < 0.05). In addition, the number of blood vessels in the uterus, height of uterine mucosal folds, villus length in endometrium, and areas of uterine mucosal folds were significantly increased in the NCG group ( P < 0.05). In conclusion, dietary 1% NCG supplementation during 0 to 25 wk can improve eggshell quality through changes in endometrial morphology, expression of calcium metabolism–related genes, and secretion of related hormones to promote eggshell formation in the laying hens.

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Section: Discussionmentioning

confidence: 99%

Improvement of eggshell quality by dietary N-carbamylglutamate supplementation in laying chickens

Yao

Zhou

et al. 2020

Poultry Science

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“…Microwave fixation was used to stabilize tissue isotope levels in our previous studies of the effects of bone-seeking hormones and drugs on the acute uptake process (Shaw & Dacke, 1985;Dacke & Shaw, 1987;Shaw & Dacke, 1989). It is particularly significant when estimating tissue 45Ca levels, this radionuclide being rapidly deposited in bone in preference to soft tissues (Neer, 1982).…”

Section: Discussionmentioning

confidence: 99%

KINETICS OF RAPID ⁴⁵Ca UPTAKE INTO CHICK SKELETON IN VIVO: EFFECTS OF MICROWAVE FIXATION

Shaw¹,

Whittaker

Dacke³

1989

Exp Physiol

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SUMMARYWe have investigated uptake kinetics for 45Ca labels acutely administered as single intravenous injections into twelve-day-old chicks in vivo. Effects of microwave fixation on this process have aJlso been studied. Rapid uptake of 45Ca was demonstrated into the skeleton with approximately 40 % of injected label being found in the skeleton within the first 15 min. By 45 min tissue 45Ca levels had stabilized and showed little change during the following 90 min. Soft tissue isotope levels declined during the period from 3 to 135 min following injection. These data were obtained from animals in which tissue isotope levels were stabilized by fixation with microwaves at the point of killing by cervical dislocation. In animals where the microwave fixation step was omitted and tissues were dissected for counting at least 1 h after killing, 45Ca levels in both skeletal and soft tissues were 15-20 % higher than in those from microwaved groups during the period 3-15 min after injection. In a separate experiment, groups of chicks killed by cervical dislocation 3 min after isotope injection were fixed with microwaves at time intervals ranging from 0 to 45 min post-mortem. Isotope levels in femur increased with time and were significantly higher in groups in which fixation was carried out 12 and 45 min after death when compared with those fixed at the point of death. Data in calvarium reflected those in femur but were not statistically significant at the time intervals tested. Estimates of unidirectional plasma-bone Ca2+ influx (JPb40Ca) into chick bone indicate high values for femur, > 1 64,tmol min-' (g wet weight)-' and calvarium, > 1 26 /umol min-1 (g wet weight)-', respectively. This suggests that Ca2+ is cleared very rapidly between blood plasma and exchangeable pools in the skeleton of the chick. Estimated JPb40Ca values decline appreciably over short (15 min) time intervals, suggesting that significant backflux of the 45Ca marker occurs. These data collectively indicate that uptake of 45Ca into skeletal tissues occurs rapidly following its injection into chicks. 45Ca uptake continues for several minutes in the immediately post-mortem animal and this process is reduced by microwave fixation. It is important to bear these factors in mind, when considering the effects of hormones and drugs on the uptake of bone-seeking radionuclides.

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Modulation of bone calcium-binding sites regulates plasma calcium: An hypothesis

Bronner

Stein

1992

Calcif Tissue Int

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A new model of calcium (Ca) homeostasis is proposed. It is based on the kinetics of restoration of the plasma Ca level following positive or negative Ca loads in animals of different endocrine status. As others, we can account for the kinetics of plasma Ca restoration as being the result of a very rapid dilution of Ca into extracellular water (t1/2 less than 1 minute) and an uptake or release by bone (t1/2 = 14-80 minutes) that occurs as the fraction of cardiac output directed to bone is partially cleared of or repleted with Ca. In this model, bone surfaces have Ca-binding sites that demonstrate a range of affinities and whose average Km determines the plasma Ca level. Acute regulation is brought about by controlling access to subpopulations of Ca binding sites in bone, comprising the extremes of high and low affinity. Osteoblasts, when active and extended, block the low affinity sites, and osteoclasts, when active and extended, block the high affinity sites. Exposure of low- or high-affinity sites is brought about when these cells respond to hormonal signals by contraction, parathyroid hormone (PTH), and vitamin D leading to osteoblast, and calcitonin to osteoclast, contraction. These reciprocal cell shape changes are the first in a cascade of metabolic events that lead to bone formation and resorption, as well as changes in the number or affinity of the binding sites. The model also accounts for the prolongation of the response time to Ca loads in animals deprived of PTH, calcitonin, or vitamin D.

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Cyclic nucleotides and the rapid inhibitions of bone45Ca uptake in response to bovine parathyroid hormone and 16,16-dimethyl prostaglandin E2 in chicks

Cited by 13 publications

References 23 publications

Improvement of eggshell quality by dietary N-carbamylglutamate supplementation in laying chickens

Improvement of eggshell quality by dietary N-carbamylglutamate supplementation in laying chickens

KINETICS OF RAPID ⁴⁵Ca UPTAKE INTO CHICK SKELETON IN VIVO: EFFECTS OF MICROWAVE FIXATION

Modulation of bone calcium-binding sites regulates plasma calcium: An hypothesis

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Cyclic nucleotides and the rapid inhibitions of bone45Ca uptake in response to bovine parathyroid hormone and 16,16-dimethyl prostaglandin E2 in chicks

Cited by 13 publications

References 23 publications

Improvement of eggshell quality by dietary N-carbamylglutamate supplementation in laying chickens

Improvement of eggshell quality by dietary N-carbamylglutamate supplementation in laying chickens

KINETICS OF RAPID 45Ca UPTAKE INTO CHICK SKELETON IN VIVO: EFFECTS OF MICROWAVE FIXATION

Modulation of bone calcium-binding sites regulates plasma calcium: An hypothesis

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KINETICS OF RAPID ⁴⁵Ca UPTAKE INTO CHICK SKELETON IN VIVO: EFFECTS OF MICROWAVE FIXATION