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Heat stress and oxidative damage after post-ischemic reperfusion
,J Mel G4
Cardiol
23 (Supplement
V) (1991)
P40 HAT SIKSS AH) CRIMTIVEDpmRuKIER KtST-ISCNMIC-IoN Evasio Pasini, of Cardiology,
,4ma Cargnoni, Claudia University of Brescia,
Ceconi, Salvatore Curello, Roberto Ferrari Italy and Diversity of London, U.K..
and r)erek
Yellon.
Chair
We studied the effects of tile body heat stress on oxidative danage occurring during ischaemia and reperfusion in the isolated rat hearts. Oxidative damage was measured in terms of nyocardial reduced (GSJ-I), oxidized (GE&) glutathione ratio as well as GSSGrelease. Rats (n 12) ware anesthetized and their body temperature raised to 42°C for 15 min. 24 hours later the hearts w-e isolated and subjected to 45 min of ischaemia with a coronary flew of 1 ml/min follcwad by 3U min of reperfusicn or utilized for heat shock protein (HSP) analysis. Controls w-e treated in the sane rnwner withcut heating. HSP expression was found in all HS hearts but in none of the controls. After reperfusicn G%/GS% mat-dial ratio of HS animaJs was higher than controls (14.4 vs 29.6, P [0.05) and GS% release reduced (0.44 vs 0.14 moles/min/~, P 4 0.01) proving a reduction of oxidative dmge. This was concomitant with a better recovery in HS animals of developed pressure (13.6 vs 40.4 rmHg, P< 0.01) less release of CPK (1903 vs 487.8 aiJ/min/q,w, P(O.01) and maintainance of ATP content (5.36 vs 6.7 ural/g&).
HEAT STRESS INCREASES TO HYPOXIC AND ZERO
THE RESISTANCE OF RABBIT CALCIUM PERFUSION.
PAPILLARY
MUSCLE
MSMarber, J.M.Walker, D.S.Latchman, D.M.Yellon. Cardiovascular Studies Unit. University College Hospital. London UK. The aim of this study was to determine if the contractility of rabbit right ventricular papillary muscle (RVPM) exposed to acidotic, zero calcium and hypoxic perfusion is influenced by prior heat stress. Rabbits (n=lO) were anaesthetisedand their temperature elevated to 42oC for 15 mins (HS). 24 hrs later their hearts were removed and RVPM mounted isometrically and stimulated at 1 Hz in an organ bath perfused with Tymde solution at 37oC. The behaviour of these muscles to sequential stresseswas compared to RVPM from non-heat stressedrabbits (n=lO). Portions of heart were removed for stress protein analysis by Western blotting and immunoprobing. l&g& For each intervention, developed tension was expressed as a % of pre-stress developed tension Values expressed as mean + SEM. Control t-test Heat Shock 72.5k4.4 p=O.26 During Acidosis 79.4 &3.9 85.7~4.3 p=o.O09 Post zero calcium 102.2~3.6 Post Hypoxiaho substrate 46.1k8.3 p=O.Ol 75.0~6.7 The stressprotein HSP 72 was elevated in each of the HS group examined. Whole body heat stressin the rabbit is associatedwith cardiac stressprotein synthesis and renders the isolated papillary muscle resistant to subsequentexposure to zero calcium and hypoxic perfusion.
FAILURE OF HEAT SHOCK @IS) RESPONSE TO LIMIT TISSUE NECRQSIS IN THE RABBIT HEART. John Kingma Jr, R William Currie*, Derek M Yellon** Quebec Heart Institute, Quebec, Canada. *Dept Anatomy, Dalhousie University, Halifax, Canada. **Cardiovascular Studies Unit, University College Hospital, London UK. Increased expression of stress proteins, such as HSP70, in ischemic myocardium may be cardioprotective. We tested this hypothesis in rabbits subjected to 45 minutes regional ischemia (IX) and I80 minutes reperfusion (REP). Two groups of male New Zealand rabbits & 2.2 Kg) were studied. Controls (n=lO) were subjected to ISC and REP without heating. In the HS group (n=9) body temperature was raised to 42’C and maintained for I5 minutes. Rabbits were allowed to recover for 40 hours and then subjected to ISC/REP Heart rate and arterial blood pressure were recorded during the experiments. by autoradiography of Area at risk was delineated microspheres (141Ce; 15um) injected intra-atrially 10 minutes after coronary occlusion. At the end of the experiment hearts were arrested during diastole with KCI. Left atrial biopsies were obtained from all rabbits to verify expression of HSP70. Expression was determined by Northern and Western blot analysis. Hearts were perfused on a Langendorff apparatus with tetrazolium chloride to determine the extent of tissue necrosis. Tissue necrosis (as % of risk zone ) was 65.3 + 9.3% in controls (mean=SEM) versus 73.6 2 8.0% (p=NS) in HS rabbits. Area at risk, area of necrosis, and cardiac hemodynamics were similar in both experimental groups. These data demonstrate that though there was an increase in the expression of HSP70 in HS rabbits the extent of tissue necrosis was not significantly reduced. We conclude that HS in rabbits, 40 hours after the initial heat stress, is not cardioprotective in this in-vivo model of myocardial infartion. s.70
Cardiol
23 (Supplement
V) (1991)
P40 HAT SIKSS AH) CRIMTIVEDpmRuKIER KtST-ISCNMIC-IoN Evasio Pasini, of Cardiology,
,4ma Cargnoni, Claudia University of Brescia,
Ceconi, Salvatore Curello, Roberto Ferrari Italy and Diversity of London, U.K..
and r)erek
Yellon.
Chair
We studied the effects of tile body heat stress on oxidative danage occurring during ischaemia and reperfusion in the isolated rat hearts. Oxidative damage was measured in terms of nyocardial reduced (GSJ-I), oxidized (GE&) glutathione ratio as well as GSSGrelease. Rats (n 12) ware anesthetized and their body temperature raised to 42°C for 15 min. 24 hours later the hearts w-e isolated and subjected to 45 min of ischaemia with a coronary flew of 1 ml/min follcwad by 3U min of reperfusicn or utilized for heat shock protein (HSP) analysis. Controls w-e treated in the sane rnwner withcut heating. HSP expression was found in all HS hearts but in none of the controls. After reperfusicn G%/GS% mat-dial ratio of HS animaJs was higher than controls (14.4 vs 29.6, P [0.05) and GS% release reduced (0.44 vs 0.14 moles/min/~, P 4 0.01) proving a reduction of oxidative dmge. This was concomitant with a better recovery in HS animals of developed pressure (13.6 vs 40.4 rmHg, P< 0.01) less release of CPK (1903 vs 487.8 aiJ/min/q,w, P(O.01) and maintainance of ATP content (5.36 vs 6.7 ural/g&).
HEAT STRESS INCREASES TO HYPOXIC AND ZERO
THE RESISTANCE OF RABBIT CALCIUM PERFUSION.
PAPILLARY
MUSCLE
MSMarber, J.M.Walker, D.S.Latchman, D.M.Yellon. Cardiovascular Studies Unit. University College Hospital. London UK. The aim of this study was to determine if the contractility of rabbit right ventricular papillary muscle (RVPM) exposed to acidotic, zero calcium and hypoxic perfusion is influenced by prior heat stress. Rabbits (n=lO) were anaesthetisedand their temperature elevated to 42oC for 15 mins (HS). 24 hrs later their hearts were removed and RVPM mounted isometrically and stimulated at 1 Hz in an organ bath perfused with Tymde solution at 37oC. The behaviour of these muscles to sequential stresseswas compared to RVPM from non-heat stressedrabbits (n=lO). Portions of heart were removed for stress protein analysis by Western blotting and immunoprobing. l&g& For each intervention, developed tension was expressed as a % of pre-stress developed tension Values expressed as mean + SEM. Control t-test Heat Shock 72.5k4.4 p=O.26 During Acidosis 79.4 &3.9 85.7~4.3 p=o.O09 Post zero calcium 102.2~3.6 Post Hypoxiaho substrate 46.1k8.3 p=O.Ol 75.0~6.7 The stressprotein HSP 72 was elevated in each of the HS group examined. Whole body heat stressin the rabbit is associatedwith cardiac stressprotein synthesis and renders the isolated papillary muscle resistant to subsequentexposure to zero calcium and hypoxic perfusion.
FAILURE OF HEAT SHOCK @IS) RESPONSE TO LIMIT TISSUE NECRQSIS IN THE RABBIT HEART. John Kingma Jr, R William Currie*, Derek M Yellon** Quebec Heart Institute, Quebec, Canada. *Dept Anatomy, Dalhousie University, Halifax, Canada. **Cardiovascular Studies Unit, University College Hospital, London UK. Increased expression of stress proteins, such as HSP70, in ischemic myocardium may be cardioprotective. We tested this hypothesis in rabbits subjected to 45 minutes regional ischemia (IX) and I80 minutes reperfusion (REP). Two groups of male New Zealand rabbits & 2.2 Kg) were studied. Controls (n=lO) were subjected to ISC and REP without heating. In the HS group (n=9) body temperature was raised to 42’C and maintained for I5 minutes. Rabbits were allowed to recover for 40 hours and then subjected to ISC/REP Heart rate and arterial blood pressure were recorded during the experiments. by autoradiography of Area at risk was delineated microspheres (141Ce; 15um) injected intra-atrially 10 minutes after coronary occlusion. At the end of the experiment hearts were arrested during diastole with KCI. Left atrial biopsies were obtained from all rabbits to verify expression of HSP70. Expression was determined by Northern and Western blot analysis. Hearts were perfused on a Langendorff apparatus with tetrazolium chloride to determine the extent of tissue necrosis. Tissue necrosis (as % of risk zone ) was 65.3 + 9.3% in controls (mean=SEM) versus 73.6 2 8.0% (p=NS) in HS rabbits. Area at risk, area of necrosis, and cardiac hemodynamics were similar in both experimental groups. These data demonstrate that though there was an increase in the expression of HSP70 in HS rabbits the extent of tissue necrosis was not significantly reduced. We conclude that HS in rabbits, 40 hours after the initial heat stress, is not cardioprotective in this in-vivo model of myocardial infartion. s.70