Mechanisms of oxalate absorption and secretion across the rabbit distal colon.
To further evaluate the mechanisms of oxalate (Ox2-) transport in the intestine the following studies were performed using isolated, short-circuited segments of the rabbit distal colon (DC). In control buffer, the DC absorbed Ox2- (net Ox2- flux, JNetOx = 5.4 +/- 0.7 pmol.cm-1.h-1). Replacement of Na+ with N-methyl-D-glucamine (NMDG+) abolished Ox2- absorption by decreasing mucosal to serosal Ox2- flux (JmsOx), without affecting Cl- transport, while gluconate substitution for Cl- did not affect JNetOx or net Na+ flux (JNetNa). Addition of Na+ to the serosal side of tissues bathed by NMDG+ buffer increased JmsOx 40% without altering mucosal to serosal Cl- flux (JmsCl). Serosal amiloride or dimethyl amiloride (10(-3) M) abolished JNetOx by decreasing JmsOx, it increased serosal to muscosal Cl- flux (JsmCl) and it gradually inhibited short-circuit current (Isc). Mucosal amiloride (10(-4) M) abolished Ise but had no effect on Ox2- or Cl- fluxes. Serosal 4,4'-diisothiocyanatostilbene-2,2'-disulfonic acid (DIDS, 10(-6) M) reduced JmsOx by 20% and JNetOx by 43% without affecting JmsCl or JNetCl. Dibutyryl cyclic adenosine monophosphate (dB-cAMP, 5 x 10(-4) M, both sides) stimulated Ox2- secretion (JNetOx = -12.6 +/- 3.3 pmol.cm-2.h-1). The dB-cAMP-induced secretion of Ox2- and Cl- were fully abolished by serosal furosemide (10(-4) M) and partially inhibited (35%) by 5 x 10(-4) M mucosal NPPB [5-nitro-2-(3-phenylpropylamino)-benzoic acid], a putative Cl- channel blocker.(ABSTRACT TRUNCATED AT 250 WORDS)
Hatch
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Department of Medicine, University of California at Irvine 92717.
Freel
R W
RW
Vaziri
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ND
D017878:4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid / Q000494:pharmacology; D000818:Animals; D001693:Biological Transport, Active / Q000187:drug effects / Q000502:physiology; D002712:Chlorides / Q000378:metabolism; D003106:Colon / Q000187:drug effects / Q000378:metabolism*; D066298:In Vitro Techniques; D007408:Intestinal Absorption / Q000187:drug effects / Q000502:physiology; D017136:Ion Transport; D007669:Kidney Calculi / Q000209:etiology; D008297:Male; D008536:Meglumine / Q000494:pharmacology; D008954:Models, Biological; D010070:Oxalates / Q000493:pharmacokinetics*; D019815:Oxalic Acid; D011817:Rabbits; D012964:Sodium / Q000378:metabolism; D017923:Sodium-Hydrogen Exchangers / Q000378:metabolism
D002712:Chlorides; D010070:Oxalates; D017923:Sodium-Hydrogen Exchangers; D008536:Meglumine; D019815:Oxalic Acid; D012964:Sodium; D017878:4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid