title: Reconstitution of human red blood cell Na/H and Na/Na exchange transport.
abstract: Na/H and Na/Na exchange transport was measured using human erythrocyte membrane proteins solubilized with octyl glucoside and reconstituted into voltage clamped soybean phospholipid membrane vesicles. The uptake of Na in exchange for either H or Na was: 1) 8 to 10 times higher in proteoliposomes that contained erythrocyte proteins than in proteoliposomes that contained heat denatured proteins or in liposomes that contained no proteins; 2) not affected by ouabain, bumetanide, or 4.4'-diisothiocyanostilbene-2-2'-disulfonic acid (DIDS); 3) inhibited by amiloride, 5-(n-ethyl-n-isopropyl)amitoride (EIPA), and 5-(n-ethyl-1-n-isobutyl)amiloride (MIA) but not phenamil; and 4) inhibited by lithium (Li) in a concentration-dependent manner. Incubation of erythrocyte proteins with a low concentration of immobilized trypsin resulted in a significant increase (52%) in Na/Na transport, but no change was seen in Na/H transport. A higher concentration of trypsin increased Na/H transport by more than 2.5 times but did not increase Na/Na transport further. Examination of these studies indicates that, as assayed in reconstituted proteoliposomes that contained erythrocyte proteins, there is a differential response between Na/H and Na/Na transport to trypsin.
authors.affiliation: Department of Medicine, West Virginia University School of Medicine, Morgantown, USA.
authors.forename: E J
authors.initials: EJ
authors.lastname: Weinman
authors.forename: H
authors.initials: H
authors.lastname: Chamras
mesh_terms: D000584:Amiloride / Q000031:analogs & derivatives / Q000494:pharmacology; D002462:Cell Membrane / Q000737:chemistry / Q000378:metabolism; D003902:Detergents / Q000494:pharmacology; D004912:Erythrocytes / Q000737:chemistry* / Q000378:metabolism; D005960:Glucosides / Q000494:pharmacology; D006801:Humans; D006863:Hydrogen-Ion Concentration; D017136:Ion Transport / Q000187:drug effects / Q000502:physiology; D008081:Liposomes / Q000378:metabolism; D008094:Lithium / Q000494:pharmacology; D008565:Membrane Proteins / Q000378:metabolism; D018408:Patch-Clamp Techniques; D010743:Phospholipids / Q000378:metabolism; D011489:Protein Denaturation; D012964:Sodium / Q000378:metabolism*; D015222:Sodium Channels / Q000378:metabolism; D017923:Sodium-Hydrogen Exchangers / Q000187:drug effects / Q000378:metabolism*; D014357:Trypsin / Q000378:metabolism / Q000494:pharmacology
chemical_list: D003902:Detergents; D005960:Glucosides; D008081:Liposomes; D008565:Membrane Proteins; D010743:Phospholipids; D015222:Sodium Channels; D017923:Sodium-Hydrogen Exchangers; C018619:octyl-beta-D-glucoside; D000584:Amiloride; D008094:Lithium; D012964:Sodium; D014357:Trypsin