EFFECTS OF PARATHYROID-HORMONE ON URINARY ACIDIFICATION IN THE RAT

Date
1991-01-01Author
Gil, Frida Zaladek [UNIFESP]
Costasilva, V. L.
Malnic, G.
Type
ArtigoISSN
0100-879XIs part of
Brazilian Journal Of Medical And Biological ResearchMetadata
Show full item recordAbstract
To evaluate the effects of parathyroid hormone (PTH) on urinary acidification parameters, thyroparathyroidectomy was performed in normal (TPTX) and in calcium-supplemented rats (TPTX+Ca2+). Both groups were supplemented with thyroxin. Glomerular filtration rate (GFR) fell from 7.79 +/- 0.33 in the control group (C) to 4.88 +/- 0.26 ml min-1 kg-1 in TPTX, while net acid excretion fell from 5.65 +/- 0.22 in C to 3.76 +/- 0.25-mu-mol min-1 kg-1 in TPTX. Kinetic data of urinary acidification obtained by microperfusion techniques in proximal tubules showed that the half-time of acidification (t/2) rose from 4.75 +/- 0.24 s in C to 8.97 +/- 0.64 s in TPTX and persisted elevated in TPTX+Ca2+ (7.40 +/- 0.43 s); in the latter group, stationary pH was not significantly different from that of the control group. Bicarbonate reabsorption (J(HCO3)) fell from 2.18 +/- 0.15 in C to 0.823 +/- 0.082 in TPTX and was 1.53 +/- 0.073 nmol s-1 cm-2 in TPTX+Ca2+. These data suggest that normal pH gradients depend on normal calcium levels, but acidification half-times are dependent on PTH, which also contributes to keeping glomerular hemodynamics and acidification rates at normal levels.
Citation
Brazilian Journal Of Medical And Biological Research. Sao Paulo: Assoc Bras Divulg Cientifica, v. 24, n. 10, p. 1063-1066, 1991.Keywords
PARATHYROID HORMONEURINARY ACIDIFICATION
THYROPARATHYROIDECTOMY
GLOMERULAR FILTRATION RATE
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- EPM - Artigos [17701]