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Relation between lipolysis and glycolysis during ischemia in the isolated perfused rat heart
47 121 RELATION BETWEEN LIPOLYSIS AND GLYCOLYSIS DURIN~ ISCHEMIA IN THE ISOLATED PERFUSED RAT HEART. V. Trach, E. Buschmans-Denkel, W. Schaper, Max-Planck-Institute, Bad Nauheim, Fed. Rep. of Germany. Ischemia (Isch) leads to an increased glycerol release which is indicative of enhanced lipolysis. As the triglyceride content remains constant, fatty acids are reesterified using glycerol-3-P. We blocked glycolysis with pyruvate and lipolysis with nicotinic acid (NA) in the nonworking rat heart. Following 30' normoxic perfusion (control) with Krebs-Henseleit-buffer + ii ~ M glucose (KH+IImM Gluc) each heart was subjected to 30' Isch (30 cm H20, 30 % 02 ) with one of 4 different substrate oonditions: group I: KH+IInlM Gluc; group II: KH+substrate free; group III: KH+5mM pyruvate; group IV: KH+IImM Gluc+10-bM NA. Icontr.n=6 I n=6 I II n=6 III n=6 IV n=6 TG(~gww) 14.02• 3.72• I 3.491.503 3.99~.425 3.72• GR(;~M/g/30 ) I .660 .310 .305 .385 Glycogan(l~M/g) 23.5• I0.52~.77 8.05• 18.08~i.13 7.40~.71 Heart Rate (b~m) 263~41 98• 66• 44~18 157~2 These data suggest that the inhibition of glycolysis results in an inhibition of lipolysis. Inhibiting lipolysis with N A has no influence on glycolysie but it inproves the function of the heart. These findings support the hypothesis that increased lipolysis during ischemia i~pairs cardiac function by an overflow of fatty acids.
122 CARNITINE INDEPENDENT OXIDATION OF LONG CHAIN FATTY ACIDS (LCFA) IN BAT HEART MITOCHONDRIA (RHM). F.Di Lisa, A.Toninello, C.R.Rossi, N.Siliprandi. Centro Fisiologia Mitocondriale CNR e Istituto Chimica Biologica, UniversitA di Padova, Italy. Activated LCFA are translocated in the intramitochondrial space by a "carnitine dependent" process. It is however possible that a portion of LCFA might freely diffuse across the inner membrane. These LCFA together with the "in situ" generated LCFA (by the action of phospholipase A 2) give rise to an intramitochondrial pool requiring an internal activation in order to undergo ~ oxidation. Present results demonstrate the existence of such "internal activation". Addition of oleate (0.05-0.2 mM) to RHM (2.5 mg/ml) resulted in an increase of oxygen 14 take without affecting the transmembrane potential. The production of CO 2 from ] Cj oleate confirmed that the increase of oxygen uptake was due to oleate 14 oxidation. Both oxygen uptake and CO 2 evolution were inhibited by the uncoupler FCCP or by a Ca excess, thus indicating that the process is energy (ATP) dependent. The improvement of oleate oxidation by olygomicin further confirms the ATP dependence of the "earnitine independent" oleate oxidation. These results are in line with those previously found in rat liver mitochondria.
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123 STIMULATION OF MYOCARDIAL CoA DEGRADATION BY FATTY ACIDS. G. D. Lopaschuk, D. A. Berkich, J. R. Neely. Department of Physiology, The Milton S. Hershey Medical Center, Hershey, PA 17033, U.S.A. In the isolated perfused rat heart, CoA levels can be increased from 537• to 818• nmol/g dry by perfusion as a Langendorff preparation for 45 minutes with buffer containing pantothenic acid (15 bM), cysteine (.i mM), and DTT (.2 mM), but no exogenous energy substrate. When these hearts were subsequently perfused as a working preparation with buffer containing glucose (ii mM) and pyruvate (5 mM) for 3 minutes, the CoA level remained high (789• nmol/g dry). However, if the pyruvate was replaced with palmitate (1.2 mM), CoA levels decreased to 683• nmol/g dry within 3 minutes. This decrease appeared to occur in the cytosolic compartment (272• to 169• nmol/g dry) and not mitochondrial (1.97• to 1.98• nmol/mg mitochondrial protein). After the 45 minutes no substrate perfusion, 80-90% of the total CoA was present as free CoA. Subsequent perfusion with pyruvate increased acetyl CoA whereas subsequent perfusion with palmitate increased both long-chain acyl and acetyl CoA. These data suggest that the cytosolic loss of total CoA may be related to high levels of long-chain acyl CoA. This effect of fatty acids does not occur in control hearts with normally low levels of cytosolic CoA. Supported by HL13028 and Canadian Heart Foundation.
122 CARNITINE INDEPENDENT OXIDATION OF LONG CHAIN FATTY ACIDS (LCFA) IN BAT HEART MITOCHONDRIA (RHM). F.Di Lisa, A.Toninello, C.R.Rossi, N.Siliprandi. Centro Fisiologia Mitocondriale CNR e Istituto Chimica Biologica, UniversitA di Padova, Italy. Activated LCFA are translocated in the intramitochondrial space by a "carnitine dependent" process. It is however possible that a portion of LCFA might freely diffuse across the inner membrane. These LCFA together with the "in situ" generated LCFA (by the action of phospholipase A 2) give rise to an intramitochondrial pool requiring an internal activation in order to undergo ~ oxidation. Present results demonstrate the existence of such "internal activation". Addition of oleate (0.05-0.2 mM) to RHM (2.5 mg/ml) resulted in an increase of oxygen 14 take without affecting the transmembrane potential. The production of CO 2 from ] Cj oleate confirmed that the increase of oxygen uptake was due to oleate 14 oxidation. Both oxygen uptake and CO 2 evolution were inhibited by the uncoupler FCCP or by a Ca excess, thus indicating that the process is energy (ATP) dependent. The improvement of oleate oxidation by olygomicin further confirms the ATP dependence of the "earnitine independent" oleate oxidation. These results are in line with those previously found in rat liver mitochondria.
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123 STIMULATION OF MYOCARDIAL CoA DEGRADATION BY FATTY ACIDS. G. D. Lopaschuk, D. A. Berkich, J. R. Neely. Department of Physiology, The Milton S. Hershey Medical Center, Hershey, PA 17033, U.S.A. In the isolated perfused rat heart, CoA levels can be increased from 537• to 818• nmol/g dry by perfusion as a Langendorff preparation for 45 minutes with buffer containing pantothenic acid (15 bM), cysteine (.i mM), and DTT (.2 mM), but no exogenous energy substrate. When these hearts were subsequently perfused as a working preparation with buffer containing glucose (ii mM) and pyruvate (5 mM) for 3 minutes, the CoA level remained high (789• nmol/g dry). However, if the pyruvate was replaced with palmitate (1.2 mM), CoA levels decreased to 683• nmol/g dry within 3 minutes. This decrease appeared to occur in the cytosolic compartment (272• to 169• nmol/g dry) and not mitochondrial (1.97• to 1.98• nmol/mg mitochondrial protein). After the 45 minutes no substrate perfusion, 80-90% of the total CoA was present as free CoA. Subsequent perfusion with pyruvate increased acetyl CoA whereas subsequent perfusion with palmitate increased both long-chain acyl and acetyl CoA. These data suggest that the cytosolic loss of total CoA may be related to high levels of long-chain acyl CoA. This effect of fatty acids does not occur in control hearts with normally low levels of cytosolic CoA. Supported by HL13028 and Canadian Heart Foundation.