Role of corticosteroids in distal acidification of amiloride-treated rats.
The role of amiloride-dependent sodium channels in the action of adrenal cortical steroids on urine-blood PCO2 (U-B PCO2) differences was studied in bicarbonate-infused and amiloride-treated adrenalectomized rats. U-B PCO2 was significantly reduced by amiloride in bicarbonate-infused control rats. Adrenalectomy further reduced U-B PCO2 in amiloride-treated, bicarbonate-infused rats (from 27.9 +/- 1.82 mmHg in sham-operated rats to 21.3 +/- 1.58 mmHg in adrenalectomized (ADX) rats) (1 mmHg = 133.322 Pa). Acute administration of corticosterone and 18-hydroxycorticosterone (18-OH-B), but not of aldosterone, caused recovery of U-B PCO2 to the level of sham-operated animals treated with amiloride. Aldosterone did not affect U-B PCO2 in the presence of amiloride (21.9 mmHg ADX group vs. 20.98 mmHg aldosterone group). Results are compatible with aldosterone affecting distal H ion secretion mostly by a sodium and potential difference dependent mechanism, while corticosterone and 18-OH-B should act by other mechanisms (e.g., increased luminal buffer level).
Ansaldo
M
M
Instituto Antártico Argentino, Buenos Aires.
Damasco
M C
MC
de Lavallaz
M S
MS
Lantos
C P
CP
Malnic
G
G
D015069:18-Hydroxycorticosterone / Q000494:pharmacology; D000305:Adrenal Cortex Hormones / Q000502:physiology*; D000315:Adrenalectomy; D000450:Aldosterone / Q000494:pharmacology; D000584:Amiloride / Q000494:pharmacology*; D000818:Animals; D002245:Carbon Dioxide; D003345:Corticosterone / Q000494:pharmacology; D005919:Glomerular Filtration Rate; D006863:Hydrogen-Ion Concentration; D008297:Male; D009399:Nephrons / Q000187:drug effects / Q000378:metabolism; D051381:Rats; D011919:Rats, Inbred Strains
D000305:Adrenal Cortex Hormones; D002245:Carbon Dioxide; D000450:Aldosterone; D015069:18-Hydroxycorticosterone; D000584:Amiloride; D003345:Corticosterone