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Blunted effect of parathyroid hormone on adenosine 3′,5′-cyclic monophosphate production is derived from ATP depletion in proximal convoluted tubules of hypophosphatemic mice (2000)

Shima, M. ; Yamaoka, K. ; Nakamura, K. ; [et al.]

Springer

Clinical and experimental nephrology 4 (2000), S. 11-17

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ISSN: 1437-7799

Keywords: Key words Extracellular phosphate ; Hypophosphatemic mice ; Adenosine 3′,5′-cyclic monophosphate ; Parathyroid hormone ; X-linked hypophosphatemic rickets

Source: Springer Online Journal Archives 1860-2000

Topics: Medicine

Notes: Abstract Background. To clarify the pathophysiological features associated with phosphate depletion in hypophosphatemic (Hyp) mice, we examined the effect of extracellular phosphate on parathyroid hormone (PTH)-stimulated adenosine 3′,5′-cyclic monophosphate (cAMP) production in the proximal convoluted tubules (PCT). Methods. PTH-Stimulated cAMP production and ATP content were determined by radioimmunoassay and luciferin-luciferase chemiluminescence methods, respectively. Results. The level of cAMP stimulated by PTH at an extracellular phosphate concentration of 0.78 mM was lower in the Hyp mice than in normal mice. The PTH-stimulated cAMP production in the Hyp mice was increased when the extracellular phosphate concentration was raised. In contrast, an increase in extracellular phosphate did not affect the PTH-stimulated cAMP production in the normal mice. Although the ATP content of the PCT was not different between the normal and Hyp mice immediately after microdissection, after 60 min of incubation, it had decreased to a greater extent in Hyp mice than in the normal animals. Raising the extracellular phosphate concentration from 0.78 to 2.3 mM prevented the decrease in ATP content in Hyp mice, and the intracellular ATP content then became comparable to that in the normal control. Conclusions. These results suggest that ATP content in the PCT tended to be decreased in Hyp mice by a decreased phosphate supply and that the blunted effect of PTH on cAMP production in these mice is due to ATP depletion.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1007/s101570050055

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An analysis of optical rotatory dispersion curves of synthetic polypeptidesThis work was supported in part by U.S. Public Health Service Grant A2558 (1964)

Yamaoka, K. K.

New York : Wiley-Blackwell

Biopolymers 2 (1964), S. 219-229

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ISSN: 0006-3525

Keywords: Chemistry ; Polymer and Materials Science

Source: Wiley InterScience Backfile Collection 1832-2000

Topics: Chemistry and Pharmacology

Notes: A two-term Drude equation was proposed to he substituted for the Moffitt-Yang equation as an empirical expression in order to analyze and regenerate observed optical rotatory dispersion (ORD) curves of synthetic polypeptides and proteins. A convenient graphical method was introduced to evaluate four parameters involved in the present expression. The method was demonstrated in detail with an observed ORD curve of sodium poly-α, L-glutamate (NaPLG) at pH 4.35. A number of ORD curves of poly-γ-benzyl-L-glutamate (PBLG) in both helix and random-coil were analyzed. For all ORD curves examined, the critical wavelengths, λ0 and λ1, were found to be 193 and 226 mμ. Aromatic solvents wore found to constitute a group distinct from other helix-forming solvents. A far ultraviolet ORD curve of NaPLG was also analyzed with use of Natanson's equation which contains two damping factors. It was concluded that for an exact description of the ORD curve of helical polypeptides a third term, probably negative, should be taken under consideration. An illustrative application of the present method to the data of the helix-coil transition of NaPLG shed much light on the relation between the four parameters and its molecular conformation as a function of pH.

Additional Material: 4 Ill.