Regulation of nephron acidification by corticosteroids
The present paper reviews work from our laboratories evaluating the importance of adrenal cortical hormones in acidification by proximal and cortical distal tubules. Proximal acidification was determined by stationary microperfusion, and measurement of bicarbonate reabsorption using luminal pH deter...
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todo:paper_0100879X_v30_n4_p479_Malnic2023-10-03T14:57:18Z Regulation of nephron acidification by corticosteroids Malnic, G. Ansaldo, M. Lantos, C.P. Damasco, M.C. aldosterone amiloride bicarbonate reabsorption corticosterone pCO2 urine 18 hydroxycorticosterone aldosterone amiloride bicarbonate carbon dioxide corticosteroid corticosterone acidification adrenalectomy animal experiment conference paper controlled study intramuscular drug administration nephron nonhuman rat urine Animalia The present paper reviews work from our laboratories evaluating the importance of adrenal cortical hormones in acidification by proximal and cortical distal tubules. Proximal acidification was determined by stationary microperfusion, and measurement of bicarbonate reabsorption using luminal pH determination was performed with H+-ion-sensitive microelectrodes. Rats were adrenalectomized (ADX) 48 h before the experiments, and corticosteroids (aldosterone (A), corticosterone (B), and 18-OH corticosterone (18-OH-B)) were injected intramuscularly 100 and 40 min before the experiments. In ADX rats stationary pH increased significantly to 7.03 as compared to sham-operated rats (6.78). Bicarbonate reabsorption decreased from 2.65 ± 0.18 in sham-operated rats to 0.50 ± 0.07 nmol cm-2 s-1 after ADX. The administration of the three hormones stimulated proximal tubule acidification, reaching, however, only 47.2% of the sham values in aldosterone-treated rats. Distal nephron acidification was studied by measuring urine minus blood pCO2 differences (U-B pCO2) in bicarbonate-loaded rats treated as above. This pCO2 difference is used as a measure of the distal nephron ability to secrete H+ ions into an alkaline urine. U-B pCO2 decreased significantly from 39.9 ± 1.26 to 11.9 ± 1.99 mmHg in ADX rats. When corticosteroids were given to ADX rats before the experiment, U-B pCO2 increased significantly, but reached control levels only when aldosterone (two 3-μg doses per rat) plus corticosterone (220 μg) were given together. In order to control for the effect of aldosterone on distal transepithelial potential difference one group of rats was treated with amiloride, which blocks distal sodium channels. Amiloride-treated rats still showed a significant reduction in U-B pCO2 after ADX. Only corticosterone and 18-OH-B but not aldosterone increased U-B pCO2 back to the levels of sham-operated rats. These results show that corticosteroids stimulate renal tubule acidification both in proximal and distal nephrons and provide some clues about the mechanism of action of these steroids. Fil:Ansaldo, M. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina. JOUR info:eu-repo/semantics/openAccess http://creativecommons.org/licenses/by/2.5/ar http://hdl.handle.net/20.500.12110/paper_0100879X_v30_n4_p479_Malnic |
| institution |
Universidad de Buenos Aires |
| institution_str |
I-28 |
| repository_str |
R-134 |
| collection |
Biblioteca Digital - Facultad de Ciencias Exactas y Naturales (UBA) |
| topic |
aldosterone amiloride bicarbonate reabsorption corticosterone pCO2 urine 18 hydroxycorticosterone aldosterone amiloride bicarbonate carbon dioxide corticosteroid corticosterone acidification adrenalectomy animal experiment conference paper controlled study intramuscular drug administration nephron nonhuman rat urine Animalia |
| spellingShingle |
aldosterone amiloride bicarbonate reabsorption corticosterone pCO2 urine 18 hydroxycorticosterone aldosterone amiloride bicarbonate carbon dioxide corticosteroid corticosterone acidification adrenalectomy animal experiment conference paper controlled study intramuscular drug administration nephron nonhuman rat urine Animalia Malnic, G. Ansaldo, M. Lantos, C.P. Damasco, M.C. Regulation of nephron acidification by corticosteroids |
| topic_facet |
aldosterone amiloride bicarbonate reabsorption corticosterone pCO2 urine 18 hydroxycorticosterone aldosterone amiloride bicarbonate carbon dioxide corticosteroid corticosterone acidification adrenalectomy animal experiment conference paper controlled study intramuscular drug administration nephron nonhuman rat urine Animalia |
| description |
The present paper reviews work from our laboratories evaluating the importance of adrenal cortical hormones in acidification by proximal and cortical distal tubules. Proximal acidification was determined by stationary microperfusion, and measurement of bicarbonate reabsorption using luminal pH determination was performed with H+-ion-sensitive microelectrodes. Rats were adrenalectomized (ADX) 48 h before the experiments, and corticosteroids (aldosterone (A), corticosterone (B), and 18-OH corticosterone (18-OH-B)) were injected intramuscularly 100 and 40 min before the experiments. In ADX rats stationary pH increased significantly to 7.03 as compared to sham-operated rats (6.78). Bicarbonate reabsorption decreased from 2.65 ± 0.18 in sham-operated rats to 0.50 ± 0.07 nmol cm-2 s-1 after ADX. The administration of the three hormones stimulated proximal tubule acidification, reaching, however, only 47.2% of the sham values in aldosterone-treated rats. Distal nephron acidification was studied by measuring urine minus blood pCO2 differences (U-B pCO2) in bicarbonate-loaded rats treated as above. This pCO2 difference is used as a measure of the distal nephron ability to secrete H+ ions into an alkaline urine. U-B pCO2 decreased significantly from 39.9 ± 1.26 to 11.9 ± 1.99 mmHg in ADX rats. When corticosteroids were given to ADX rats before the experiment, U-B pCO2 increased significantly, but reached control levels only when aldosterone (two 3-μg doses per rat) plus corticosterone (220 μg) were given together. In order to control for the effect of aldosterone on distal transepithelial potential difference one group of rats was treated with amiloride, which blocks distal sodium channels. Amiloride-treated rats still showed a significant reduction in U-B pCO2 after ADX. Only corticosterone and 18-OH-B but not aldosterone increased U-B pCO2 back to the levels of sham-operated rats. These results show that corticosteroids stimulate renal tubule acidification both in proximal and distal nephrons and provide some clues about the mechanism of action of these steroids. |
| format |
JOUR |
| author |
Malnic, G. Ansaldo, M. Lantos, C.P. Damasco, M.C. |
| author_facet |
Malnic, G. Ansaldo, M. Lantos, C.P. Damasco, M.C. |
| author_sort |
Malnic, G. |
| title |
Regulation of nephron acidification by corticosteroids |
| title_short |
Regulation of nephron acidification by corticosteroids |
| title_full |
Regulation of nephron acidification by corticosteroids |
| title_fullStr |
Regulation of nephron acidification by corticosteroids |
| title_full_unstemmed |
Regulation of nephron acidification by corticosteroids |
| title_sort |
regulation of nephron acidification by corticosteroids |
| url |
http://hdl.handle.net/20.500.12110/paper_0100879X_v30_n4_p479_Malnic |
| work_keys_str_mv |
AT malnicg regulationofnephronacidificationbycorticosteroids AT ansaldom regulationofnephronacidificationbycorticosteroids AT lantoscp regulationofnephronacidificationbycorticosteroids AT damascomc regulationofnephronacidificationbycorticosteroids |
| _version_ |
1807316725429960704 |