Calcium-45, uptake

Studies of other bone-seeking radionuclides provide further support for increased vulnerability during periods of rapid bone growth such as adolescence (Carnes et al. 1997 Lloyd et al. 1999). On the other hand, americium uptake into maternal bone of lactating rats was similar to that of nonlactating rats, while concurrent calcium uptake into bone was lower in lactating rats (Hollins and Durakovic 1972). Thus, active mobilization of bone mineral, per se, may not always promote release of americium from bone (see Section 3.4.2.1). 

Al-Batshan H.A., Scheideler S.E., Black B.L., Garlich J.D. and Anderson K.E. (1994). Duodenal calcium uptake, femur ash, and eggshell quality decline with age and increase following molt , Poultry Science, 73, 1590-1596. 

Weibel, F.P. (1997). Enhancing calcium uptake in organic apple growing , Acta... 

Considerable evidence suggests that the major site of calcium sequestration and the source of intracellular calcium for signaling is the ER. In addition to the points already made, subcellular fractionation studies have demonstrated positive correlations of ATP-dependent Ca2+ accumulation and of IP3-mediated Ca2+ release with classical enzymatic markers for ER. Calcium uptake into the IP3-sensitive store is augmented by oxalate this augmentation is a property generally associated with the ER. 

Nickel may be a factor in asbestos carcinogenicity. The presence of chromium and manganese in asbestos fibers may enhance the carcinogenicity of nickel (USEPA 1980), but this relation needs to be verified. Barium-nickel mixtures inhibit calcium uptake in rats, resulting in reduced growth (WHO 1991). Pretreatment of animals with cadmium enhanced the toxicity of nickel to the kidneys and liver (USPHS 1993). Simultaneous exposure to nickel and cadmium — an industrial situation... 

Doherty, J.D., K. Nishimura, N. Kurihara, and T. Fujita. 1986. Quantitative structure-activity studies of substituted benzyl chrysanthemates. 9. Calcium uptake inhibition in crayfish nerve cord and lobster axon homogenates in vitro by synthetic pyrethroids. Pestic. Biochem. Physiol. 25 295-305. 

Ramadan, A.A., N.M. Bakry, A.S.M. Marei, A.T. Eldefrawi, and M.E. Eldefrawi. 1988. Action of pyrethroids on K+-stimulated calcium uptake by, and (3H)nimodipine binding to, rat brain synaptosomes. Pestic. Biochem. Physiol. 32 114-122. 

Doherty JD, Nishimura K, Kurihara N, Fujita T (1987) Promotion of norepinephrine release and inhibition of calcium uptake by pyrethroids in rat brain synaptosomes. Pestic Biochem Physiol 29 187-196... 

Gerasimenko, J. V., Tepikin, A. V., Petersen, O. H. and Gerasimenko, O. V. (1998). Calcium uptake via endocytosis with rapid release from acidifying endo-somes, Current Biol., 8, 1335-1338. 

Mercuric chloride is thought to gain access to the intracellular compartment through Na + and Ca2 + channels in the membrane [ 100]. Sulphydryl reagents, including Hg2 +, could inhibit K +-stimulated uptake of Ca2+ into rat brain synaptosomes in vitro [101]. In muscle sarcoplasmic reticulum, Hg2+ causes inhibition of ATP-dependent Ca2 + uptake and loss of accumulated calcium [ 102,103]. However, HgCl2 has been found to inhibit ATP-dependent calcium uptake more strongly than it inhibits potassium-stimulated uptake [ 104],... 

At the cellular level, chlordecone causes spontaneous neurotransmitter release (End et al. 1981) and increases in free intracellular calcium in synaptosomes (Bondy and Halsall 1988 Bondy and McKee 1990 Bondy et al. 1989 Komulainen and Bondy 1987). This appears to be due at least in part to increased permeability of the plasma membrane (Bondy and Halsall 1988 Bondy and McKee 1990 Bondy et al. 1989 Komulainen and Bondy 1987), activation of voltage-dependent calcium channels (Komulainen and Bondy 1987), and inhibition of brain mitochondrial calcium uptake (End et al. 1979, 1981). 

Agarwal AK, Mehendale HM. 1986. Effect of chlordecone on carbon tetrachloride-induced increase in calcium uptake in isolated perfused rat liver. Toxicol Appl Pharmacol 83 342-348. Cited in text... 

Calcium is the major mineral component of bone and normal repair and remodelling of bone is reliant on an adequate supply of this mineral. Calcium uptake in the gut, loss through the kidneys and turnover within the body are controlled by hormones, notably PTH and 1,25 dihydroxy cholecalciferol (1,25 DHCC or 1,25 dihydroxy vitamin D3 or calcitriol). Refer to Figure 8.12 for a summary of the involvement of PTH and vitamin D3 in controlling plasma calcium concentration. These two major hormones have complementary actions to raise plasma calcium concentration by promoting uptake in the gut, reabsorption in the nephron and bone resorption. Other hormones such as thyroxine, sex steroids and glucocorticoids (e.g. cortisol) influence the distribution of calcium. 

R.S. Tuan, C.J. Moore, J.W. Brittingham, J.J. Kirwin, R.E. Akins, and M. Wong. In vitro study of placental trophoblast calcium uptake using JEG-3 human choriocarcinoma cells. J Cell Sci. 98 (Pt 3) 333-342 (1991). 

Lurrie, S., Fallik, E., and Klein, J. D., 1996, The effect of heat treatment on apple epiculticular wax and calcium uptake. Postharvest Biology and Technology 8 271-277. 

Once formed, 1,25-DHCC acts on duodenal epithelial cells as a lipid-soluble hormone. Its intracellular receptor (a Zn-finger protein) binds to response elements in enhancer regions of DNA to induce the synthesis of calcium-binding proteins thought to play a role in stimulating calcium uptake from the GI tract. 

INTESTINE (Duodemjm) increase calcium uptake from intestine... 

Vitamin D (calciferol) Produced in skin by action of ultraviolet Controls calcium uptake into the body and... 

Resorption of the required mineral substances from food usually depends on the body s requirements, and in several cases also on the composition of the diet. One example of dietary influence is calcium (see p. 342). Its resorption as Ca is promoted by lactate and citrate, but phosphate, oxalic acid, and phytol inhibit calcium uptake from food due to complex formation and the production of insoluble salts. 

Wingrove, D.E., Amatruda, J. and Gunter, T.E. (1984) Glucagon effects on the membrane potential and calcium uptake rate of rat liver mitochondria. Journal of Biological Chemistry, 259 (15), 9390-9394. 

Roth-Bassell, FI. A., and Clydesdale, F. M. (1991). The influence of zinc, magnesium, and iron on calcium uptake in brush border membrane vesicles. /. Am. Coll. Nutr. 10, 44- 9. 

Srivastava SP, Chen NQ, Floltzman JL. 1990. The in vitro NADPFI- dependent inhibition by CCFof the ATP-dependent calcium uptake of hepatic microsomes from male rats. J Biol Chem 265 8392-8399. 

B) Decreasing calcium uptake by competing for binding sites... 

It has been postulated that 2-PAM exerts its cardiac action in rabbit atria through its alteration of calcium metabolism. The relaxation phase of skeletal muscle contraction seems to be directly affected by the sarcoplasmic reticulum because of its ability to sequester calcium actively.29,46 a similar role has been suggested for the sarcoplasmic reticulum in cardiac muscle. 6,83 The onset of muscle contraction takes place when calcium reaches a crit-cal concentration. This contraction is later reduced by the increased calcium-sequestering activity of the sarcoplasmic reticulum. Thus, 2-PAM can affect this process by decreasing the rate of calcium uptake by the sarcoplasmic reticulum, which results in increasing the time required to reduce the calcium concentration enough to allow relaxation to take place. This was demonstrated by the Increase in the relaxation phase. It was suggested that this... 

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