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Mitochondrial phospholipids in myocardial ischaemia
338 MITOCHONDRIAL
PHOSPHOLIPIDS IN MYOCARDIAL ISCHAEMIA. A. Lochner, T. Victor, C. la Cock, N. van der Merwe. M.R.C. Molecular and Cellular Cardiology Unit, Department of Medical Physiology and Biochemistry, University of Stellenbosch Medical School, Tygerberg, R.S.A. Disturbances in phospholipid metabolism of myocardial membrane systems may cause irreversible cell damage in myocardial ischaemia. To test this hypothesis, the isolated working rat heart was subjected to different periods of global ischaemia. Subsequently mitochondrial membrane properties were investigated by assaying the phospholipid contents, phospholipid fatty acid composition and membrane microviscosity. These findings were correlated with (i) mechanical activity during reperfusion and (ii) ultrastructure. The results showed that changes in mitochondrial phospholipid content is a relatively late event in ischaemia and occur after the onset of irreversibility. However, changes in the free fatty acid composition of these phospholipids (especially lysophosphatidylcholine and lysophosphatidylethanolamine) precede development of irreversible changes. These changes in phospholipid fatty acid composition were reflected in an increase in mitochondrial membrane microviscosity. In summary, the results obtained indicate that changes in the mitochondrial phospholipid fatty acid composition and microviscosity coincide witn uevelopment of ultrastructural changes and precedes mechanical failure during reperfusion.
339REVERSAL OF ISCHEMIA-INDUCED MITOCHONDRIAL DYSFUNCTION AFTER CORONARY REPERFUSION. K. Kotaka, Y. Miyazaki, S.Nagai, K. Ogawa, T. Satake, S,Sugiyama* and T. Ozawa*. Departments of Internal Medicine and%iomedical Chemistry, Faculty of Medicine, University of Nagoya, Nagoya, Japan. This study was designed to clarify the mechanism of the reversal of ischemia-induced dysfunction of mitochondria (Mt.) after a reperfusion of the myocardium in dogs. The occlusion of the left anterior descending coronary artery for 30 min led to the significant increase of acyl-CoA level in ischemic Mt. and the function of ischemic Mt. was disturbed. Pre-infusion of 1 ml/kg of lipid before occlusion further increased the acyl-CoA accumulation in ischemic Mt., and concomitantly, the dysfunction of Mt. was extended much more. On the other hand, 40 min of reperfusion following 30 min of occlusion diminished the accumulation of acyl-CoA in the reperfused Mt. and restored the function of Mt.. However, when lipid was pre-infused, acyl-CoA level in Mt. was retained at high level even after reperfusion and dysfunction of Mt. was observed. Administration of carnitine prior to reperfusion prevented the accumulation of acyl-CoA in the reperfused Mt. and preserved the function of the Mt., despite the pre-infusion of There was a clear reciprocal correlation (r=-0.97) between acyl-CoA level and lipid. the function ofMt..These results suggest that acyl-CoA accumulation is one of important factors in ischemia-induced dysfunction of Mt., and the reversal of the dysfunction after reperfusion is closely dependent upon the level of accumulated acyl-CoA.
340 CYCLIC
NCCLEfXIDE PHosPHODIl5TERAsE ACTTMTIES B.Tantini, CULTURES. *E.Turchetto, *C.Pignatti, ca Biolqica e*Centro Ricerche sulla Nutrizione,
IN PHCSPHOLIPIB-TREATEB HEART CELL S.Manfroni, C.ClB. Istituto di Chili-
Facolta
di Pkdicina,
Universiti
di
Emlogna, E%ologna (Italy). The n-etabolic and functional pendent on CAMP and cG!P as well
activities of heart cells in culture are closely deas on the supply of lipids with the medium. Usually
serum
of
represents
the
only
source
lipids
for
cultured
cells.
In
confluent
and se-
ru~~starved chick embryo heart cell cultures the addition of phospholipids, such ds phosphatidylethamlaine (20 ug/m.l of madim), phosphatidylcholine (20 i>g/ml) or phosphatidylserine (50 ug/ml) causes an early and significant decrease of cellular CAMP content and an increase of CCMP content by modulating the specific cyclic nuSimilar effects were observed after senm cleotide phosphodiesterase activities. readdition to serm-starved cultures. Both the high and the low Km cAMPdependent phosphodiesterase activities of soluble (25,ooO x g) and particulate fractions of heart cells are increased within 5 to XI tin of exposure of the cultures to phospholipids. Conversely e-dependent phosphodiesterase activity, specially that of the particulate fraction, declines follming the addition of each phospholipid to the cells. A significant increase in guanylate cyclase activity was also observed in the sane exparirrmtal conditions. Supported
by a grant
of
Minister0
Pubblica
Istruzione,
Rone
(Italy).
PHOSPHOLIPIDS IN MYOCARDIAL ISCHAEMIA. A. Lochner, T. Victor, C. la Cock, N. van der Merwe. M.R.C. Molecular and Cellular Cardiology Unit, Department of Medical Physiology and Biochemistry, University of Stellenbosch Medical School, Tygerberg, R.S.A. Disturbances in phospholipid metabolism of myocardial membrane systems may cause irreversible cell damage in myocardial ischaemia. To test this hypothesis, the isolated working rat heart was subjected to different periods of global ischaemia. Subsequently mitochondrial membrane properties were investigated by assaying the phospholipid contents, phospholipid fatty acid composition and membrane microviscosity. These findings were correlated with (i) mechanical activity during reperfusion and (ii) ultrastructure. The results showed that changes in mitochondrial phospholipid content is a relatively late event in ischaemia and occur after the onset of irreversibility. However, changes in the free fatty acid composition of these phospholipids (especially lysophosphatidylcholine and lysophosphatidylethanolamine) precede development of irreversible changes. These changes in phospholipid fatty acid composition were reflected in an increase in mitochondrial membrane microviscosity. In summary, the results obtained indicate that changes in the mitochondrial phospholipid fatty acid composition and microviscosity coincide witn uevelopment of ultrastructural changes and precedes mechanical failure during reperfusion.
339REVERSAL OF ISCHEMIA-INDUCED MITOCHONDRIAL DYSFUNCTION AFTER CORONARY REPERFUSION. K. Kotaka, Y. Miyazaki, S.Nagai, K. Ogawa, T. Satake, S,Sugiyama* and T. Ozawa*. Departments of Internal Medicine and%iomedical Chemistry, Faculty of Medicine, University of Nagoya, Nagoya, Japan. This study was designed to clarify the mechanism of the reversal of ischemia-induced dysfunction of mitochondria (Mt.) after a reperfusion of the myocardium in dogs. The occlusion of the left anterior descending coronary artery for 30 min led to the significant increase of acyl-CoA level in ischemic Mt. and the function of ischemic Mt. was disturbed. Pre-infusion of 1 ml/kg of lipid before occlusion further increased the acyl-CoA accumulation in ischemic Mt., and concomitantly, the dysfunction of Mt. was extended much more. On the other hand, 40 min of reperfusion following 30 min of occlusion diminished the accumulation of acyl-CoA in the reperfused Mt. and restored the function of Mt.. However, when lipid was pre-infused, acyl-CoA level in Mt. was retained at high level even after reperfusion and dysfunction of Mt. was observed. Administration of carnitine prior to reperfusion prevented the accumulation of acyl-CoA in the reperfused Mt. and preserved the function of the Mt., despite the pre-infusion of There was a clear reciprocal correlation (r=-0.97) between acyl-CoA level and lipid. the function ofMt..These results suggest that acyl-CoA accumulation is one of important factors in ischemia-induced dysfunction of Mt., and the reversal of the dysfunction after reperfusion is closely dependent upon the level of accumulated acyl-CoA.
340 CYCLIC
NCCLEfXIDE PHosPHODIl5TERAsE ACTTMTIES B.Tantini, CULTURES. *E.Turchetto, *C.Pignatti, ca Biolqica e*Centro Ricerche sulla Nutrizione,
IN PHCSPHOLIPIB-TREATEB HEART CELL S.Manfroni, C.ClB. Istituto di Chili-
Facolta
di Pkdicina,
Universiti
di
Emlogna, E%ologna (Italy). The n-etabolic and functional pendent on CAMP and cG!P as well
activities of heart cells in culture are closely deas on the supply of lipids with the medium. Usually
serum
of
represents
the
only
source
lipids
for
cultured
cells.
In
confluent
and se-
ru~~starved chick embryo heart cell cultures the addition of phospholipids, such ds phosphatidylethamlaine (20 ug/m.l of madim), phosphatidylcholine (20 i>g/ml) or phosphatidylserine (50 ug/ml) causes an early and significant decrease of cellular CAMP content and an increase of CCMP content by modulating the specific cyclic nuSimilar effects were observed after senm cleotide phosphodiesterase activities. readdition to serm-starved cultures. Both the high and the low Km cAMPdependent phosphodiesterase activities of soluble (25,ooO x g) and particulate fractions of heart cells are increased within 5 to XI tin of exposure of the cultures to phospholipids. Conversely e-dependent phosphodiesterase activity, specially that of the particulate fraction, declines follming the addition of each phospholipid to the cells. A significant increase in guanylate cyclase activity was also observed in the sane exparirrmtal conditions. Supported
by a grant
of
Minister0
Pubblica
Istruzione,
Rone
(Italy).