Parathyroid hormone adenosine monophosphate

Factors controlling calcium homeostasis are calcitonin, parathyroid hormone(PTH), and a vitamin D metabolite. Calcitonin, a polypeptide of 32 amino acid residues, mol wt - SGOO, is synthesized by the thyroid gland. Release is stimulated by small increases in blood Ca " concentration. The sites of action of calcitonin are the bones and kidneys. Calcitonin increases bone calcification, thereby inhibiting resorption. In the kidney, it inhibits Ca " reabsorption and increases Ca " excretion in urine. Calcitonin operates via a cyclic adenosine monophosphate (cAMP) mechanism. 

Herrmann-Erlee, M. P. M. A parathyroid hormone-like action of dibutyryl cyclic adenosine-3 ,5 monophosphate on the explanted embryonic mouse radius. Calc. Tiss. Res. 4, (Suppl.) 70 (1970)... 

Peck, W. A., Carpenter, J., Messinger, K., De Bra, D. Cyclic 3 ,5 -adenosine monophosphate in isolated bone cells Response to low concentrations of parathyroid hormone. Endocrinology 92, 692 (1973)... 

Rodan, S. G., Rodan, G. A. The effect of parathyroid hormone and thyreocalcitonin on the accumulation of cyclic adenosine 3 ,5 -monophosphate in freshly isolated bone cells. J. Biol. Chem. 249, 3068 (1974)... 

Brown, EM, Fuleihan, Ge-H, Chen, CJ and Kifor, O, 1990, A comparison of the effects of divalent and trivalent cations on parathyroid hormone release, 3, 5 -cyclic-adenosine monophosphate accumulation, and the levels of inositol phosphates in bovine parathyroid cells, Endocrinology 127 1064-1071... 

Firstly, Cd causes renal damage with effects principally on renal tubular cells, i.e. the site of la,25-dihy-droxyvifamin D synfhesis resulfing in an infrinsic vitamin D deficiency. This will impair the gastrointestinal absorption of calcium, reduce the calcium incorporation in bone and ultimately result in the development of osteomalacia. It is well known that la,25-dihydroxyvi-tamin D is the biologically active metabolite of vitamin D. As there is a sequential relationship between the synthesis of la,25-dihydroxyvitamin D in the kidney and cyclic-adenosine monophosphate, adenylcyclase, parathyroid hormone, a direct interference of Cd with any of these steps cannot be excluded. 

Features of lithium-induced hyperparathyroidism include a) a low urinary calcium excretion and the absence of nephrolithiasis b) normal urinary cyclic adenosine monophosphate excretion and c) normal plasma inorganic phosphate [30]. In lithium-induced hypercalcemia, a higher frequency of conduction defects has been noted [42]. Lithium also inhibits parathyroid hormone-mediated renal reabsorption of Ca and Mg and blunts parathyroid hormone-mediated phos-phaturia [43]. Lithium interferes with the formation of renal cyclic adenosine monophosphate, which is regulated by parathyroid hormone. Levels of minary cy-... 

Brown, E. M., Gardner, D. G., Windeck, R. A., and Aurbach, G. D., 1979, Cholera toxin stimulates 3, 5 -adenosine monophosphate accumulation and parathyroid hormone release from dispersed bovine parathyroid glands. Endocrinology 104 218. 

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