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Intracellular volume of rat hearts and oedema during ischemia- 1H and Co59 NMR studies
J
Mel Cell Cardiol 24 (Supplement V) (1992)
Poster presentation:
October 2,1992
8.30 - 17.50
Myocardial Ischemiu and Preconditioning 162
volume of rat hearts and oedema during ischemia‘H and CoT9 NMR studies Nadir Askenasy, Maria Tassini, Antonio Vivi, Gil Navon. School of Chemistry, Tel Aviv University, Tel Aviv 69978, Israel An experimental chamber with constant volume was built inside a 15 mm NMR tube. The Krebs-Henseleit perfusion solution contained 2 mM Co(CN)i3 as an extracellular marker. Three compartments were defined: Vin intracellular, V extracellular compartments, V, the water free space. The compartments were determines from integral differences of the signals of the experimental chamber full of solution (I,) and containing the heart (I,,): s9Co NMR: Vi,+ V,= k(Ic-I$ ‘H NMR: V,=kH(IE-It,); k,k” were determined by the calibration procedure. The physiological intracellular volume of rat hearts is 2.45zKl.13 ml/gdw. During 30 minutes of normothermic global ischemia the compartment swelled by 16% with a linear pattern. At reperfusion the volume was higher by 7% than the initial vahte It is concluded that the intracellular compartment oedema develops during the ischemic stage and is partially relieved by reperfusion.
182
THE CALCIUM ANTAGONIST NISOLDIPINE ATTENUATES CORONARY REACTIVE HYPEREMIA BY REDUCING THE RELEASE OF DILATOR CATASOLITES FROM ISCHEMIC MYOCARDIUM. Thomas Ehring and Gerd Heusch. Dept. of Pathophysiology, University Essen, FRG. It is currently unclear whether the attenuation of coronary reactive hyperemia (RH) by calcium antagonists is caused by a reduced formation and release of dilator catabolites ID) or an interaction with D at the coronary vascular wall. To distinguish these two potential mechanisms, 32 open-chest dogs were subjected to 15 min LCX-occlusion and subsequent reperfusion. 8 dogs each served as placebo-controls, received Nisoldipine IN.5 pglkg i.v.) before occlusion, after 10 min occlusion, or at 4 min reperfusion. Posterior transmural myocardial blood flow (TF. ml/min/a.colored microsoheres) was measured at control (C), 13 min occlusion (01, and 10 min raperfusion IRiO). Meanaortic pressurewas kept constant, and heart rate did not change. Dataare mean r SD: C C+N 0 RlO
Intracellular
Placebo-control N before
0
Nat 10minO N at 4 min reperfusion
1.42
f
1.30
f 0.43
0.43
1.24 1.19
zt 0.44 f 0.50
2.52
i 0.66
0.26
f
0.08
2.07
f
0.93
0.22
_c 0.14
1.31
f
0.51
0.17 0.09
+ 0.07 f 0.04
1.74 2.47
f 0.80 f 0.62
RH at Fit0 (2.07 -e 0.93) was completely suppressed when N was infused before 0. When given late during 0, N attenuated RH (1.74 f 0.80). Thus, the attenuation of RH depends on the duration of action of N on the ischemic myocardium. To what extent N or D contributed to the increased TF at RlO (2.47 i 0.621, when N was given at 4 min reperfusion, can not be distinguished. These results indicate, that there is no inhibitory interaction between N and D at the coronary vascular wall. The effect of N on RH appears to be related to the inhibition of the formation and release of D during myocardial ischemia.
187
ENHANCED EXPRESSION OF HSP 27 mRNA DURING ISCHEMIC PRECONDITIONING IN SWINE. Janusz An&es, Hari S. Sharma, ‘Dirk J. Duncker, ‘Lees Sassen. *Pieter D. Verdouw, Wolfgang Schaper, Max-Planck-Institute, Bad Nauheim, F.R. Germany; ‘Thoraxcenter, Erasmus University Rotterdam, The Netherlands. Induction of heat shock proteins (HSP) may contribute to cellular resistance to subsequent ischemic stress. We examined the expression of HSP 27 kd mRNA in preconditioned swine myocardium. lschemic preconditioning was achieved by two cycles of 10 min occlusion of the left anterior descending coronary artery (LAD) and 30 min reperfusion (REP), followed by additional 60, 90, and 180 min REPS. Systolic wall thickening was decreased to 38% of the control value at 30 min of first and second REPS and remained depressed during additional REPS. The myocardial tissue from ischemic (E) and nonischemic (C) regions of the heart were analysed by Northern blot employing a radiolabeled human HSP 27 cDNA probe (StressGen). Densitometric analysis revealed a 2-3 fold induction of HSP 27 mRNAs (0.9 and 1 .l kb bands) in E as compared to C after two cycles of ischemia and 30 mm REP. This expression remained elevated 1.5 fold in E as compared to C during additional REPS. There was no significant difference in the expression of H(SP 27 mRNA between E and C regions in sham operated animals; (glyceraldehyde phosphate dehydrogenase mRNA expression has been used as standard). We conclude, that two cycles of short ischemia and REP induce expression of the HSP 27 mRNA. which might be involved in protective and/or adaptative changes during ischemic preconditioning. s.87
Mel Cell Cardiol 24 (Supplement V) (1992)
Poster presentation:
October 2,1992
8.30 - 17.50
Myocardial Ischemiu and Preconditioning 162
volume of rat hearts and oedema during ischemia‘H and CoT9 NMR studies Nadir Askenasy, Maria Tassini, Antonio Vivi, Gil Navon. School of Chemistry, Tel Aviv University, Tel Aviv 69978, Israel An experimental chamber with constant volume was built inside a 15 mm NMR tube. The Krebs-Henseleit perfusion solution contained 2 mM Co(CN)i3 as an extracellular marker. Three compartments were defined: Vin intracellular, V extracellular compartments, V, the water free space. The compartments were determines from integral differences of the signals of the experimental chamber full of solution (I,) and containing the heart (I,,): s9Co NMR: Vi,+ V,= k(Ic-I$ ‘H NMR: V,=kH(IE-It,); k,k” were determined by the calibration procedure. The physiological intracellular volume of rat hearts is 2.45zKl.13 ml/gdw. During 30 minutes of normothermic global ischemia the compartment swelled by 16% with a linear pattern. At reperfusion the volume was higher by 7% than the initial vahte It is concluded that the intracellular compartment oedema develops during the ischemic stage and is partially relieved by reperfusion.
182
THE CALCIUM ANTAGONIST NISOLDIPINE ATTENUATES CORONARY REACTIVE HYPEREMIA BY REDUCING THE RELEASE OF DILATOR CATASOLITES FROM ISCHEMIC MYOCARDIUM. Thomas Ehring and Gerd Heusch. Dept. of Pathophysiology, University Essen, FRG. It is currently unclear whether the attenuation of coronary reactive hyperemia (RH) by calcium antagonists is caused by a reduced formation and release of dilator catabolites ID) or an interaction with D at the coronary vascular wall. To distinguish these two potential mechanisms, 32 open-chest dogs were subjected to 15 min LCX-occlusion and subsequent reperfusion. 8 dogs each served as placebo-controls, received Nisoldipine IN.5 pglkg i.v.) before occlusion, after 10 min occlusion, or at 4 min reperfusion. Posterior transmural myocardial blood flow (TF. ml/min/a.colored microsoheres) was measured at control (C), 13 min occlusion (01, and 10 min raperfusion IRiO). Meanaortic pressurewas kept constant, and heart rate did not change. Dataare mean r SD: C C+N 0 RlO
Intracellular
Placebo-control N before
0
Nat 10minO N at 4 min reperfusion
1.42
f
1.30
f 0.43
0.43
1.24 1.19
zt 0.44 f 0.50
2.52
i 0.66
0.26
f
0.08
2.07
f
0.93
0.22
_c 0.14
1.31
f
0.51
0.17 0.09
+ 0.07 f 0.04
1.74 2.47
f 0.80 f 0.62
RH at Fit0 (2.07 -e 0.93) was completely suppressed when N was infused before 0. When given late during 0, N attenuated RH (1.74 f 0.80). Thus, the attenuation of RH depends on the duration of action of N on the ischemic myocardium. To what extent N or D contributed to the increased TF at RlO (2.47 i 0.621, when N was given at 4 min reperfusion, can not be distinguished. These results indicate, that there is no inhibitory interaction between N and D at the coronary vascular wall. The effect of N on RH appears to be related to the inhibition of the formation and release of D during myocardial ischemia.
187
ENHANCED EXPRESSION OF HSP 27 mRNA DURING ISCHEMIC PRECONDITIONING IN SWINE. Janusz An&es, Hari S. Sharma, ‘Dirk J. Duncker, ‘Lees Sassen. *Pieter D. Verdouw, Wolfgang Schaper, Max-Planck-Institute, Bad Nauheim, F.R. Germany; ‘Thoraxcenter, Erasmus University Rotterdam, The Netherlands. Induction of heat shock proteins (HSP) may contribute to cellular resistance to subsequent ischemic stress. We examined the expression of HSP 27 kd mRNA in preconditioned swine myocardium. lschemic preconditioning was achieved by two cycles of 10 min occlusion of the left anterior descending coronary artery (LAD) and 30 min reperfusion (REP), followed by additional 60, 90, and 180 min REPS. Systolic wall thickening was decreased to 38% of the control value at 30 min of first and second REPS and remained depressed during additional REPS. The myocardial tissue from ischemic (E) and nonischemic (C) regions of the heart were analysed by Northern blot employing a radiolabeled human HSP 27 cDNA probe (StressGen). Densitometric analysis revealed a 2-3 fold induction of HSP 27 mRNAs (0.9 and 1 .l kb bands) in E as compared to C after two cycles of ischemia and 30 mm REP. This expression remained elevated 1.5 fold in E as compared to C during additional REPS. There was no significant difference in the expression of H(SP 27 mRNA between E and C regions in sham operated animals; (glyceraldehyde phosphate dehydrogenase mRNA expression has been used as standard). We conclude, that two cycles of short ischemia and REP induce expression of the HSP 27 mRNA. which might be involved in protective and/or adaptative changes during ischemic preconditioning. s.87