248A AASLD ABSTRACTS HEPATOLOGY October 1995

565 ORAL "C GALACTOSE BREATH TEST FOR THE QUANTITATIVE MEASUREMENT OF LIVER FUNCTION. A. Jakiche. R. Meyer. J. M. Henderson. C. Aanor. P. Behrans. J. Dcleote. W.D. Carev. Dept of Gastroenterology and Hepatology, Dept of Surgery. The Cleveland Clinic Foundation, Cleveland, OH. Background: 90-95% of galaetose is metabolized in the liver• The metabolism rate follows zero order kinetics when the serum galaetose level is ~40 mg/dl. At this point, galaetose elimination rate reflects hepatic function. Intravenous galactese elimination capacity (GEC) is cmTenfly used for this measurement. Oral administration of t*C labeled galactose provides a potentially simpler way to quantitatively evaluate hepatic function by measuring ~CO2 in the breath, the end product of galectose metabolism. This study assesses the efficacy of oral ~C galactose breath test (OGBT) in measuring hepatic function, and evaluates the correlation between OGBT and GEC. Methods: The study was performed in three steps (days 1, 3, 5) on 5 normal controls and 5 patients with cirrhosis (2 Child A, 1 Child B, and 2 Child C). On days I and 3 respectively, 25 gm and 50 gm of galaetose were co-administered orally with 100 mg/m 2 13C galactose. Breath and serum samples were obtained every 30 minutes. Breath ~-CO2/CO2 ratio was measured by an isotope ratio mass spectrometer, and the rate of JaC galactose oxidation to uCO2 in the breath (%*sC dose/hour) was calculated. On day 5 intravenous GEC was performed. Results: 50 gm oral galactose resulted in serum level ~40 mg/dl in all but one cirrhotic patient and one control• Analysis of those who achieved adequate serum saturation is presented. The breath */eric dose/hour was significantly lower in patients with cirrhosis than controls at all measurements between 90-180 min (table). Percent of ~sC dose/hour exhaled in breath:

30 rain 60 min 90 min 120 rain 150 min 180 min PatientS" 10.344-0.1811.12±-0.561 1.874-0.82 12.57±1.02 13.33+1.12 13.834-1.27 ] Controls** [ i .80-~.89 [4.464-2.0316.194-1.29" 16.90±-0.68" 17.19A0.26" 17.06-4-0.64"1

* P<0.005 ** Results expressed as mean 4-SD In controls %~3C dose/hour reached a steady rate at 120 min and seemed to represent hepatic galactose metabolism. In patients the rate continued to increase up to 180 min. There was a good correlation between GEC and OGBT at 30 (~-0.g5), 60 (r---0.85), 90 (r=0.86) and 120 rain (r=0.84). Patients with Child's A cirrhosis had higher OGBT results than those with Child's B and C cirrhosis. Conclusion: 1) 50 gm oral galactose achieves adequate serum saturation in 80% of cases. 2) OGBT is a safe noninvasive test that correlates well with GEC and clearly distinguishes those with cirrhosis from normals. 3) In cirrhoties but not in normals, OGBT at 120-180 min seems to reflect extraneous factors in edditon to hepatic metabolism; the clinical effects of these factors is minimal.

566 HEPATIC HAEMODYNAMIC CHANGES INDUCED BY S E ~ TOXIC LIVER INJURY. AJ Makin. RD Hughes. Roner Williams. Institute of Liver Studias, King's College School of Medicine and Dentistry, London SE5 9PJ, UK.

Hepatic failure induces a hyperdynamic circulation with impaired microcirculatory blood flow and tissue hypoxia. Aim: To determine the relationship between portal venous and hepatic arterial hemodynamies during the course of severe toxic liver injury. Methods: Hepatocelinlar injury was induced in rats by galactosamine (l . lg/kg, i.p.). Cardiac output, hepatic arterial (HABF) and portal venous 0aVBF) blood flow were measured in anesthetised rats (n=6-10) using the radioactive microsphare technique. Hepatic arterial (DhaOz) and portal venous (DpvOz) oxygen ddivary were ealcolated from blood flow values and direct measurements of arterial and portal venous blood oxygen content. Results: Cardiac output increased from baseline 240 + 12•7 ml/min to 404 + 17•5 ml/min by 48h.

Time post Galactnsamine Injection (hours) Control(0) 12 24 48

MAP (mmHg) 115 __ 6.0 99 4- 1.3" 84 4- 1.5" 90 4-3.5" HABF (ml/min/g) 0.6 _+ 0.1 1.0 4- 0.2" 4 . 5 4- 0.7" 5.8 +0.7* PVBF (ml/min/g) 2.6 _+ 0.2 4.3 __ 0.6* 5.8 4- 0.9* 10.5 + 1.2" DhaO2 (mlOJmin/kg 1.5 4- 0.1 2.2 4- 0.4 9 .2 4- 1.0" 9.9 4- 1.3" DpvO 2 (mlOJmin/kg) 3.2 4- 0.1 5.7 4- 0.6* 5.9 -I- 1.0" 9.7 -4- 1.2" Mean + SEM * - p < 0.05 compared to control.

Total hepatic blood flow increased by 60% within 12 hours of galactosamine administration, mainly due to increased PVBF. HABF increased by 450% over the' next 12 hours, becoming the dominant supply of delivered oxygen, with little change in PVBF. At 48 hours total hepatic blood flow had increased by 500% from initial values with oxygen delivered equally by arterial and portal venous circulations. Blood flow and oxygen delivery returned to control values by 72 hours: Conclusion: These variations in the hepatic circulation may have important implications for the management of fulminant hepatic failure. The inotropic agents used to maintain the MAP are vasoconstrictors and may thus impair arterial blood flow and oxygen delivery at a stage when the artery is the main source of delivered oxygen further compromising cellular function and exacerbating the hepatic injury.

567 A CRITICAL BALANCE BETWEEN ENDOTHELINS AND NITRIC OXIDE REGULATES PORTAL RESISTANCE AFTER E ~ T O X I N PRETREATMENT. BILl Pannen~ M Bauer. JX Zhan~. JL Robotham. MG Clemens. Johns Hopkins Medical Institutions, Baltimore, Maryland

To test whether endothelins (ET) are involved in the regulation of portal resistance afrer endotoxin pretreatment, and to determine if the effects of ET are modulated by nitric oxide (NO), rats received i.p. injections of 1 mg/kg g coli lipopolysaccharide (LPS) or saline (Sham). Six hours later livers were isolated perfused and analyses of portal resistance and epifluorescence video miereseopy were performed before (BL) and after the NO- synthesis-inhibitor N?~- Nitro-L-Arginine Methyl Ester (L-N, 1 mM, POST-l), followed by L- Arginine (L-A; 2 rnM~ POST-2), or the ETA+ B receptor antagonist bosentan (BOS, 200 laM; POST-1 ), followed by L- N (1 raM, POST-2). At BL, livers from LPS- pretreated animals had higher portal vascular resistances and narrower

~ 2

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sinusoids compared to livers from sham animals. There was a small ET-induced basal portal vasoconstrictive tone, but no evidence for an NO-mediated vasodilation in livers from sham animals. ET contributed to the increased portal resistance afrer LPS-pretreamaent, predominantly via a profound sinusoidal constrictive effect. This ET-mediated sinusoidal constriction was only partially counterbalanced by NO. Thus, a critical balance between ET and NO controls portal resistance alter endotoxin pretreatment. Supported in part bY' NIH DK38201 (M.G.C.), NIH HL-39138-04 (J.LR.) and DFG Pa 533/1-1+2 (BH.JP.).

568 R O L E OF ENDOTHELIUM-DERIVED HYPERPOLARIZING F A C T O R IN ETHANOL-INDUCED VASOCONSTRICTION M Oshita, T Hiiioka, Y Takei, N Hayashi, S Kawano, H Fusamoto and TKamada. l s tDcpt , of Med., Osaka Univ. Sch. of Med., Osaka, Japan.

We have shown that hepatic vascular tone is regulated by an interaction of endothelin-1 and nitric oxide (NO) in the presence of ethanol and, at concentrations of ethanol -> 25mM, ethanol induced vasocostdction which leads to hepatic tissue hypoxia, followed by dysfunction and necrosis in the liver (Hepatology 16:1007,1992, J Clin Invest 91:1337,1993). The aim of this study was to investigate the role of endothelium-dedved hyperpolarizng factor (EDHF) which hyperpotarized vascular smooth muscle by activating membrane K + channels in ethanol-induced hepatic vasoconstriction. METHODS: Rat livers were peffnsed with Krebs-Henseleit buffer in an open system at a constant flow rate. Ethanol was infused into the influent for 30 rain and portal pressure (PP) was monitored continuously as an indicator of vasoconstriction. The degree of hepatic vasoconstriction was represented by the averaged change in PP during 30 rain of ethanol infusion (AvePP). RESULTS: (1)When ethanol was infused into the influent, PP was increased, reaching the peak values at 3-5 rain, and thereafter decreased gradually ("escape" phenomena). (2)Simultaneous infusion of an NO inhibitor, Nt°-nitro-L-arginine (LNA) (1001.tM) with ethanol (100raM) abolished "escape" phenomena and enhanced AvePP significandy (p<0.01), but simultaneous infusion of an nonselective K + channel blocker, tetramethylammonium (TMA) ( lmM) with ethanol did not increase AvePP. (3)However, infusion of both TMA and LNA with ethanol increased AvePP which is higher than that in LNA infusion (p<0.05) (see Table)• CONCLUSIONS: Under the condition of blocking an action of NO, EDHF decreased ethanol-induced increase in PP. These results suggest that NO is mainly responsible for escape phenomena and exhibits a synergistic effect of EDHF in ethanol- induced hepatic vasoconstriction.

< Effect of TMA and LNA on AvePP (mmH20) > ethanol ethanol+LNA ethanol+TMA ethanol+TMA+LNA

AvePP 18Y.2 43_+4 19-~ 56~.7