Wesson DE, Dolson GM. Endothelin-1 increases rat distal tubule acidification in vivo.
THE AMERICAN JOURNAL OF PHYSIOLOGY 1997;
273:F586-94. [PMID:
9362336 DOI:
10.1152/ajprenal.1997.273.4.f586]
[Citation(s) in RCA: 11] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Because endothelin receptor inhibition blunts increased distal tubule acidification induced by dietary acid, we examined whether endothelin-1 (ET-1) increases acidification of in vivo perfused distal tubules of anesthetized rats. ET-1 was infused intraaortically (1.4 pmol x kg(-1) x min[-1]) into control animals and into those with increased distal tubule HCO3 secretion induced by drinking 80 mM NaHCO3 solution for 7-10 days. ET-1 increased distal tubule acidification in both control and NaHCO3 animals. Increased acidification in control animals was mediated by increased distal tubule H+ secretion (23.7+/-2.2 vs. 18.7 +/- 1.7 pmol x mm(-1) x min(-1), P < 0.05) with no changes in HCO3 secretion. By contrast, ET-1 increased distal tubule acidification in NaHCO3 animals predominantly by decreasing HCO3 secretion (-9.5 +/- 1.0 vs. -18.7 +/-1.8 pmol x mm(-1) x min(-1), P < 0.001) with less influence on H+ secretion. When indomethacin was infused (83 microg x kg(-1) x min[-1]) to inhibit synthesis of prostacyclin, an agent previously shown to increase HCO3 secretion in the distal tubule, ET-1 increased distal tubule H+ secretion in both control (24.3 +/-2.2 vs. 15.7 +/- 1.6 pmol x mm(-1) x min(-1), P < 0.02) and NaHCO3 (20.0 +/- 2.0 vs. 13.6 +/- 1.4 pmol x mm(-1) x min(-1), P < 0.05) without affecting HCO3 secretion. The data show that ET-1 increases distal tubule acidification in vivo and can do so by increasing H+ secretion and by decreasing HCO3 secretion when the latter is augmented by dietary NaHCO3.
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