Acute effects of two natural corticosteroids on the kinetics of the Na+/H+ exchanger in rat renal brush-border membranes
We studied the effect of adrenalectomy and acute hormone replacement, using physiological doses of natural corticosteroids, on the kinetics of the Na+/H+ exchanger in brush border membrane vesicles. We collected the data using the acridine orange uptake technique. Adrenalectomized (ADX) rats present...
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todo:paper_00084212_v75_n10-11_p1226_Igarreta2023-10-03T14:06:05Z Acute effects of two natural corticosteroids on the kinetics of the Na+/H+ exchanger in rat renal brush-border membranes Igarreta, P. Calvo, J.C. Paladini, A. Damasco, M.C. 18-OH-corticosterone Adrenalectomy Amiloride Corticosterone Na+/H+ antiporter 18 hydroxycorticosterone adenosine triphosphatase (potassium sodium) amiloride corticosteroid corticosterone adrenalectomy animal experiment animal tissue article brush border controlled study enzyme inhibition fluorescence hormone substitution kidney proximal tubule michaelis menten kinetics nonhuman priority journal rat 18-Hydroxycorticosterone Acid-Base Equilibrium Adrenalectomy Amiloride Animals Anti-Inflammatory Agents Corticosterone Diuretics Kidney Kinetics Male Microvilli Rats Rats, Sprague-Dawley Sodium Sodium-Hydrogen Antiporter We studied the effect of adrenalectomy and acute hormone replacement, using physiological doses of natural corticosteroids, on the kinetics of the Na+/H+ exchanger in brush border membrane vesicles. We collected the data using the acridine orange uptake technique. Adrenalectomized (ADX) rats presented a decreased maximal rate (V(max)) when compared with sham-operated animals (30 000 versus 41 000 fluorescent units/min, respectively). Administration of corticosterone (B) to ADX rats restored V(max) to values above control (up to 66,000 fluorescent units/min). Smaller doses of 18-OH-B led to similar results. K(m) (16 mM) remained the same for all the groups. Amiloride behaved as a pure competitive inhibitor, with a K(i) = 0.02 mM and an I50 = 98 μM (in the presence of 50 mM sodium gluconate). The presence of sodium in the external buffer, before adding the vesicles, inhibited the exchange, with an I50 = 2 mM. We observed, a significant decrease in the Na+/H+ exchanger under non-acidotic conditions in response to adrenalectomy. Acute administration of physiological doses of natural occurring corticosteroids reversed the effect. Fil:Calvo, J.C. 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_00084212_v75_n10-11_p1226_Igarreta |
| institution |
Universidad de Buenos Aires |
| institution_str |
I-28 |
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R-134 |
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Biblioteca Digital - Facultad de Ciencias Exactas y Naturales (UBA) |
| topic |
18-OH-corticosterone Adrenalectomy Amiloride Corticosterone Na+/H+ antiporter 18 hydroxycorticosterone adenosine triphosphatase (potassium sodium) amiloride corticosteroid corticosterone adrenalectomy animal experiment animal tissue article brush border controlled study enzyme inhibition fluorescence hormone substitution kidney proximal tubule michaelis menten kinetics nonhuman priority journal rat 18-Hydroxycorticosterone Acid-Base Equilibrium Adrenalectomy Amiloride Animals Anti-Inflammatory Agents Corticosterone Diuretics Kidney Kinetics Male Microvilli Rats Rats, Sprague-Dawley Sodium Sodium-Hydrogen Antiporter |
| spellingShingle |
18-OH-corticosterone Adrenalectomy Amiloride Corticosterone Na+/H+ antiporter 18 hydroxycorticosterone adenosine triphosphatase (potassium sodium) amiloride corticosteroid corticosterone adrenalectomy animal experiment animal tissue article brush border controlled study enzyme inhibition fluorescence hormone substitution kidney proximal tubule michaelis menten kinetics nonhuman priority journal rat 18-Hydroxycorticosterone Acid-Base Equilibrium Adrenalectomy Amiloride Animals Anti-Inflammatory Agents Corticosterone Diuretics Kidney Kinetics Male Microvilli Rats Rats, Sprague-Dawley Sodium Sodium-Hydrogen Antiporter Igarreta, P. Calvo, J.C. Paladini, A. Damasco, M.C. Acute effects of two natural corticosteroids on the kinetics of the Na+/H+ exchanger in rat renal brush-border membranes |
| topic_facet |
18-OH-corticosterone Adrenalectomy Amiloride Corticosterone Na+/H+ antiporter 18 hydroxycorticosterone adenosine triphosphatase (potassium sodium) amiloride corticosteroid corticosterone adrenalectomy animal experiment animal tissue article brush border controlled study enzyme inhibition fluorescence hormone substitution kidney proximal tubule michaelis menten kinetics nonhuman priority journal rat 18-Hydroxycorticosterone Acid-Base Equilibrium Adrenalectomy Amiloride Animals Anti-Inflammatory Agents Corticosterone Diuretics Kidney Kinetics Male Microvilli Rats Rats, Sprague-Dawley Sodium Sodium-Hydrogen Antiporter |
| description |
We studied the effect of adrenalectomy and acute hormone replacement, using physiological doses of natural corticosteroids, on the kinetics of the Na+/H+ exchanger in brush border membrane vesicles. We collected the data using the acridine orange uptake technique. Adrenalectomized (ADX) rats presented a decreased maximal rate (V(max)) when compared with sham-operated animals (30 000 versus 41 000 fluorescent units/min, respectively). Administration of corticosterone (B) to ADX rats restored V(max) to values above control (up to 66,000 fluorescent units/min). Smaller doses of 18-OH-B led to similar results. K(m) (16 mM) remained the same for all the groups. Amiloride behaved as a pure competitive inhibitor, with a K(i) = 0.02 mM and an I50 = 98 μM (in the presence of 50 mM sodium gluconate). The presence of sodium in the external buffer, before adding the vesicles, inhibited the exchange, with an I50 = 2 mM. We observed, a significant decrease in the Na+/H+ exchanger under non-acidotic conditions in response to adrenalectomy. Acute administration of physiological doses of natural occurring corticosteroids reversed the effect. |
| format |
JOUR |
| author |
Igarreta, P. Calvo, J.C. Paladini, A. Damasco, M.C. |
| author_facet |
Igarreta, P. Calvo, J.C. Paladini, A. Damasco, M.C. |
| author_sort |
Igarreta, P. |
| title |
Acute effects of two natural corticosteroids on the kinetics of the Na+/H+ exchanger in rat renal brush-border membranes |
| title_short |
Acute effects of two natural corticosteroids on the kinetics of the Na+/H+ exchanger in rat renal brush-border membranes |
| title_full |
Acute effects of two natural corticosteroids on the kinetics of the Na+/H+ exchanger in rat renal brush-border membranes |
| title_fullStr |
Acute effects of two natural corticosteroids on the kinetics of the Na+/H+ exchanger in rat renal brush-border membranes |
| title_full_unstemmed |
Acute effects of two natural corticosteroids on the kinetics of the Na+/H+ exchanger in rat renal brush-border membranes |
| title_sort |
acute effects of two natural corticosteroids on the kinetics of the na+/h+ exchanger in rat renal brush-border membranes |
| url |
http://hdl.handle.net/20.500.12110/paper_00084212_v75_n10-11_p1226_Igarreta |
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