Hepatic metabolism during acute ethanol administration: A phosphorus-31 nuclear magnetic resonance study on the perfused rat liver under normoxic or hypoxic conditions

Abstract

The effect of ethanol metabolism on the energetic parameters and intracellular pH of the isolated perfused rat liver from fed rats was studied by phosphorus-31 nuclear magnetic resonance spectroscopy. This technique allowed us to analyze nondestructively and in real time the role of low oxygen tension on the possible injurious effect of ethanol on the liver cells. A quantitative analysis of nuclear magnetic resonance data recorded on a perfused rat liver within a 30 mm diameter probe has been performed at 80.9 MHz. Under normoxic and normothermic conditions, the levels of phosphorylated metabolites detected by nuclear magnetic resonance were 2.8, 0.3 and 2 mumoles per gm liver wet weight for ATP, ADP and inorganic orthophosphate, respectively. The cytosolic pH was 7.25 +/- 0.05. During a period of 4 min of hypoxia induced by reducing the perfusion flow rate to 25% of its initial value (i.e., from 12 ml to 3 ml per min per 100 gm body weight), the level of ATP dropped to 2.2 mumoles per gm liver wet weight. Concomitantly, ADP and inorganic orthophosphate increased to 0.6 and 3.3 mumoles per gm liver wet weight. Cytosolic pH fell to 7.02 +/- 0.05. Perfusion of the liver with a Krebs medium containing 70 mM (0.4%) ethanol induced a sharp decrease in intracellular inorganic orthophosphate to reach 1.3 mumole per gm liver wet weight and after a lag time of 4 to 6 min, a decrease in ATP level (2.15 mumoles per gm liver wet weight). A large increase in phosphomonoesters (mainly sn-glycerol 3-phosphate) up to 6 mumoles per gm liver wet weight was also observed.(ABSTRACT TRUNCATED AT 250 WORDS)

Effects of the mycelial extract of cultured Cordyceps sinensis on in vivo hepatic energy metabolism and blood flow in dietary hypoferric anaemic mice

“…Interestingly, no significant changes were observed in hepatic intracellular pH, which is determined by the chemical shift difference between the Pi and a-ATP peaks in the 31 P NMR spectra, in any group, indicating that the Cs extract had no severe hepatotoxicity and maintained normoxic conditions. In general, intracellular acidosis can be induced by hepatotoxic reagents and hypoxic conditions (Desmoulin et al 1987;Takahashi et al 1990). Moreover, histopathological findings have revealed that Cs extract does not induce severe hepatotoxic changes in the liver, i.e.…”

“…The decrease in ATP consumption attributed to depressed Na pump function can theoretically produce a high energy state in the liver (Takahashi et al 1990). When Na pump function is depressed by toxic agents and hypoxic conditions, severe intracellular acidosis is induced (Desmoulin et al 1987;Takahashi et al 1990). However, no such decrease in ATP consumption occurred in the liver of Cs-extract-treated mice, because no severe changes were observed in liver intracellular pH.…”

Use of Diethyl(2-methylpyrrolidin-2-yl)phosphonate as a Highly Sensitive Extra- and Intracellular 31P NMR pH Indicator in Isolated Organs

“…The novel phosphorylated pyrrolidine diethyl(2-methylpyrrolidin-2-yl)phosphonate (DEPMPH) was evaluated as a 31 P NMR probe of the pH changes associated with ischemia/reperfusion of rat isolated hearts and livers. In vitro titration curves indicated that DEPMPH exhibited a 4-fold larger amplitude of chemical shift variation than inorganic phosphate yielding an enhanced NMR sensitivity in the pH range of 5.0 -7.5 that allowed us to assess pH variations of less than 0.1 pH units.…”

“…Because of the dependence of the chemical shift of phosphates on pH (1-3), 31 P NMR spectroscopy has progressively become the standard method for the measurement of intracellular pH (pH i ) 1 in biological systems, mostly using inorganic orthophosphate (P i ) as a naturally occurring pH probe (4 -6). Although this technique was first applied to measure pH in a variety of biological fluids, the development of pulsed Fourier transform NMR and wide-bore supraconducting magnets has soon allowed the noninvasive study of cell cultures and isolated perfused organs under physiologic or pathologic conditions.…”

“…Although this technique was first applied to measure pH in a variety of biological fluids, the development of pulsed Fourier transform NMR and wide-bore supraconducting magnets has soon allowed the noninvasive study of cell cultures and isolated perfused organs under physiologic or pathologic conditions. In particular, the use of 31 P NMR has considerably increased our understanding of the dynamics of pH i changes during ischemia-induced acidosis in the heart (7-9) and liver (10,11). Although P i resonance has been successfully used to describe the main pH i -regulatory systems in these organs (12,13), more subtle trans-sarcolemmal proton movements that could occur in different pathologies may escape investigation if they are related to extra-and intracellular pH values different by less than 0.2-0.3 pH units (4).…”