HEPATIC TRANSPORT OF A FLUORESCENT STEARATE DERIVATIVE - ELECTROCHEMICAL DRIVING FORCES IN INTACT RAT-LIVER

被引:26
作者
FITZ, JG
BASS, NM
WEISIGER, RA
机构
[1] UNIV CALIF SAN FRANCISCO,DEPT MED,SAN FRANCISCO,CA 94143
[2] UNIV CALIF SAN FRANCISCO,CTR LIVER,SAN FRANCISCO,CA 94143
来源
AMERICAN JOURNAL OF PHYSIOLOGY | 1991年 / 261卷 / 01期
关键词
ISOLATED PERFUSED RAT LIVER; LONG-CHAIN FATTY ACID; LOBULAR GRADIENT; SODIUM-COUPLED TRANSPORT; MEMBRANE POTENTIAL DIFFERENCE; MICROELECTRODES; ELECTROGENIC TRANSPORT; CARRIER-MEDIATED TRANSPORT;
D O I
10.1152/ajpgi.1991.261.1.G83
中图分类号
Q4 [生理学];
学科分类号
071003 ;
摘要
We determined the effect of varying the transmembrane Na+ electrochemical gradient on extraction of a fluorescent derivative of stearate, 12-N-methyl-7-nitrobenzo-2-oxa-1,3-diazol-amino stearate (NBD-stearate), by the isolated perfused rat liver. Membrane potential difference (PD) of individual hepatocytes and extraction of NBD-stearate were measured simultaneously under basal conditions and during changes in PD induced by perfusate ion substitutions. Under basal conditions, PD averaged -30 +/- 1 mV, and extraction of 10-mu-M NBD-stearate from 1% albumin solutions averaged 0.54 +/- 0.03. Fluorescence microscopy indicated that uptake exhibited a declining portal-to-central gradient in the presence but not absence of Na+. Substitution of nitrate for Cl- hyperpolarized PD to -59 mV and increased extraction to 131% of control values. Withdrawal of nitrate and substitution of gluconate for Cl- depolarized PD to -3 and -15 mV, respectively, and decreased extraction to 63 and 73% of control values. Substitution of choline for Na+ eliminated the out-to-in Na+ gradient, depolarized PD to -16 mV, and decreased extraction to 27% of control values, an effect greater than expected for membrane depolarization alone. Uptake of NBD-stearate was saturable and caused Na+-dependent membrane depolarization at higher concentrations (300-mu-M). These studies indicate that uptake of NBD-stearate occurs in large part by an efficient Na+-dependent mechanism compatible with electrogenic Na+-fatty acid cotransport.
引用
收藏
页码:G83 / G91
页数:9
相关论文
共 33 条
[1]  
ABUMRAD NA, 1984, J BIOL CHEM, V259, P8945
[2]  
ABUMRAD NA, 1981, J BIOL CHEM, V256, P9183
[3]  
BASS NM, 1989, RBC-CELL BIOL REV, V19, P61
[4]  
BASS NM, 1986, GASTROENTEROLOGY, V90, P1710
[5]   INCREASED SINUSOIDAL VOLUME AND SOLUTE EXTRACTION DURING RETROGRADE LIVER PERFUSION [J].
BASS, NM ;
MANNING, JA ;
WEISIGER, RA .
AMERICAN JOURNAL OF PHYSIOLOGY, 1989, 256 (06) :G1041-G1048
[6]   EFFICIENT CLEARANCE OF NON-TRANSFERRIN-BOUND IRON BY RAT-LIVER - IMPLICATIONS FOR HEPATIC IRON LOADING IN IRON OVERLOAD STATES [J].
BRISSOT, P ;
WRIGHT, TL ;
MA, WL ;
WEISIGER, RA .
JOURNAL OF CLINICAL INVESTIGATION, 1985, 76 (04) :1463-1470
[7]   IONIC TRANSPORT AND MEMBRANE-POTENTIAL OF RAT-LIVER CELLS IN NORMAL AND LOW-CHLORIDE SOLUTIONS [J].
CLARET, B ;
CLARET, M ;
MAZET, JL .
JOURNAL OF PHYSIOLOGY-LONDON, 1973, 230 (01) :87-101
[8]   THE EFFECT OF NORADRENALINE ON THE ION PERMEABILITY OF ISOLATED MAMMALIAN HEPATOCYTES, STUDIED BY INTRACELLULAR-RECORDING [J].
FIELD, AC ;
JENKINSON, DH .
JOURNAL OF PHYSIOLOGY-LONDON, 1987, 392 :493-512
[9]   ELECTROPHYSIOLOGICAL EVIDENCE FOR NA+-COUPLED BICARBONATE TRANSPORT IN CULTURED RAT HEPATOCYTES [J].
FITZ, JG ;
PERSICO, M ;
SCHARSCHMIDT, BF .
AMERICAN JOURNAL OF PHYSIOLOGY, 1989, 256 (03) :G491-G500
[10]   INTRACELLULAR CHLORIDE ACTIVITY IN INTACT RAT-LIVER - RELATIONSHIP TO MEMBRANE-POTENTIAL AND BILE-FLOW [J].
FITZ, JG ;
SCHARSCHMIDT, BF .
AMERICAN JOURNAL OF PHYSIOLOGY, 1987, 252 (05) :G699-G706