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The effect of selenium added cardioplegia in guinea pigs
~
Pergamon
0306-3623(94)E0096-5
Gen. Pharmac. Vol. 25, No. 7, pp. 1493-1497, 1994 Copyright© 1994ElsevierScienceLtd Printed in Great Britain.All rights reserved 0306-3623/94 $7.00+ 0.00
The Effect of Selenium Added Cardioplegia in Guinea Pigs HALiM SONCUL*, O~UZ TATLICAN, VELiT HALiT, ESER OZ, VOLKAN SINCI, ERGUN SALMAN, LEVENT GOKGOZ, NURTEN T1SIRKOZKAN and ALI ERSOZ Departments of Cardiovascular Surgery and Biochemistry, Gazi University Medical Faculty, Ankara, Turkey (Received 28 January 1994)
Abstract--1. The aim of the study was to determine the effect of selenium added cardioplegic solutions on postischemic myocardial recovery. 2. The hearts were mounted on Langendorf perfusion apparatus and perfused with Krebs-Henseleit solution. The hearts were arrested by one of the following cardioplegic solutions; (a) K + 20 mmol/1 (control group); (b) K ÷ 20 mmol/l + selenium 10-3 mol/1 (experimental group). After 20 min of normothermic ischemia the hearts were reperfused by the same buffer. 3. Postischemic percentage changes of heart rate, contractile force and heart work were compared between the groups. 4. Addition of selenium to the cardioplegic solution significantly decreased the postischemic myocardial injury.
KeyWords:Selenium, cardioplegia, ischemic injury
INTRODUCTION Interest in the role of selenium in the pathogenesis of cardiovascular disease originated from observations of blood pressure changes, cardiomyopathy and sudden cardiac death in animals with dietary selenium deficiency (Burk, 1978). There are also a number of clinical, ecological and epidemiological studies investigating the relationship between the serum selenium concentration and ischemic cardiac disease in humans (Ringstad et al., 1987; Salonen et al., 1982; Oster et al., 1990). Selenium deficiency affects several cellular mechanisms that have been implicated in the pathogenesis of atherosclerosis. Selenium depletion is accompanied by a decrease in the activity of glutathione peroxidase, a selenium containing enzyme present in several tissues, including platelets, arterial walls and the heart (Salonen and Huttunen, 1986). This enzyme has very important functions in the removal of hydrogen peroxide and fatty acid hydroperoxides in the cell. Glutathione peroxidase may also influence prostaglandin and leukotriene metabolism in platelets and *To whom all correspondence should be addressed.
in other tissues. Therefore selenium is a part of a system that provides a means of defense against the accumulation of lipid peroxides and free radicals that damage cell membranes and macro molecules. There is still intensive interest in different cardioplegic solutions, techniques and cardioplegic additives for better myocardial protection during cardiac operations. Several studies have demonstrated that myocardial protection with cardioplegic solutions can be improved by adding agents to inhibit oxyradical production or to degrade the reactive species (Johansen et al., 1988; Menache et al., 1986). In this study we aimed to test the effect of selenium added to conventional cardioplegic solutions on postischemic cardiac recovery. MATERIALS AND M E T H O D S Animals and perfusion techniques Hearts were obtained from male guinea pigs (n = 24) weighing 330-440 g. All animals received human care in compliance with the "Principles of Laboratory Animal Care" formulated by the National Society for Medical Research and the "Guide for the Care and Use of Laboratory Animals" prepared by
1493
1494
HALiMSONCULet al.
the National Academy of Sciences and published by the National Institutes of Health (NIH Publication No. 80-23, revised 1978). The animals were anaesthetized by ether and given 200 units of heparin into the femoral vein. The hearts (1.8-2.4 g) were rapidly removed and cannulated via the aorta. They were then mounted on a modified Langendorf perfusion apparatus and perfused by a gassed (O2 95%, CO2 5%) Krebs-Henseleit solution at a rate of 10 ml/min, at 37°C. The composition of the solution was as follows (in raM/l) NaHCO3, 25; NaCI, 118; KH2PO4, 1.2; KCI, 4.8; MgSO4, 1.2; CaC12, 1.2; and glucose, 11.1. Protocol
After 15 min the heart had begun to work, we recorded the contractile force (mm/g) and the heart rate (beats/min). The hearts were arrested by introduction of one of the cardioplegic solutions (K ÷ 20mmol/1 in the control group (Plegisol), K ÷ 20 mmol/1 and Selenium 10 3mol/l in the experimental group) from the aortic root for 3 rain (at a rate of 10 ml/min at 4°C). During the ischemic period the hearts were kept at normothermic conditions. After 20 min of ischemia the reperfusion was begun by the same buffer at 37°C. The ventricular contractilforce and heart rate were recorded again just after the ischemic period and also at the 20th min of reperfusion. (Fig. 1) Calculations
The following calculations were made:
Percentage recovery of heart rate = Postischemic heart rate x 100 Preischemic heart rate Percentage recovery of contractile force-Postischemic contractions × 100 Preischemic contractions Percentage recovery of heart work = Postischemic heart rate x postischemic contractions x 100 Preischemic heart rate x preischemic contractions Data and statistics
Ventricular contractileforce (mm/g) and heart rate (beat/min) were recorded through an isometric force transducer (UGO BASILE 7004), (a resting tension of 5 g was applied) connected to a (UGO BASILE 7050) microdynomorneter. The results are presented as mean and standard error of the mean. Overall significance of differences between groups was determined by t-test using the "Microsoft Excel 4.0" PC program. RESULTS The mean percentage change of the heart rate was significantly higher in the selenium group after the ischemic period (102% vs 83%, P = 0.06) and also after the reperfusion (110% vs 89%, P = 0.02).
Perfusion with Krebs solution
Pump
~
I
[....Transducer .......................
5 grams
Fig. 1. Experimental design. Data were recorded just before the ischemia, after the ischemic period and after 20 min of reperfusion.
Selenium cardioplegia
1495
Heart rate
125
~o 100
75
5~ PreAfter reperfusion
Contractile force
120
IO0
,.~
80
6C
4~
PreAfter reperfusion
Heart work
120
I00 ¢J
~*
80
60
40 Pre-i After reperfusioa Fig. 2. Comparison of the percentage changes of heart rate, contractile force and heart work in groups. 5~" indicates a statistical difference (P < 0.05) between the two groups, ,¢~;~ indicates a statistical difference (P < 0.005) between the two groups, ~ indicates a significant difference between the indicated value and pre-ischemic value.
1496
HALiMSONCULet al. Table I. Percentagechanges of mechanical parametersbetween the groups Heart rate
Contractile force
Heart work
Control Pre-ischemic Post-ischemic After reperfusion
100% 83.1% ± 8.4% 89.0% ± 8.9%
100% 60.7% + 6.3% 54.0% +_ 7.4%
100% 51.1% + 4.8% 47.7% + 6.9%
Selenium Pre-ischemic Post-ischemic After reperfusion
100 % 102% +_9.4% 110.0% +_ 12.5%
100% 86.6% _+ 7.3% 91.0% +_ 10.0%
100 % 84.3% _+6.2% 92.1% ± 11.5%
Values are percentagechange accordingto the pre-ischemicvalues(mean+ SEM).
For the contractile force, again we achieved similar results. The mean percentage change of the contractile force was significantly higher in the selenium group after the ischemia (86% v 60%, P = 0.03) and after the reperfusion (91% v 54%, P = 0.05). For the heart work parameter, which is defined by us (heart rate × contractile force), the differences between the groups were again statistically significant both after ischemia (P = 0.0005) and after reperfusion (P = 0.002) (Fig. 2, Table 1).
explained by its role in the glutathione peroxidase system.
DISCUSSION
SUMMARY
In hearts with relatively normal preoperative ventricular performance, hypothermic potassium cardioplegia provides adequate protection during aortic-clamping. However, the same cardioplegic strategies do not adequately protect hearts with antecedent global or regional ischemia and when cardioplegic arrest is prolonged. A number of reports suggest that the pathogenesis of cardiac ischemic injury may be partly ascribed to the production of activated oxygen species (Johansen et al., 1988; Omar et al., 1991). Therefore, much interest has been focused on the trace element selenium, which is an essential prosthetic group for the enzyme glutathione peroxidase. This enzyme reduces lipid hydroperoxides to the corresponding lipid alcohols (or water), thereby possibly protecting the epithelium from oxidative damage (Rotruck et al., 1973). Glutathione peroxidase may also influence the synthesis of prostacyclin, an agent protective against platelet aggregation (Schoene et al., 1984). There are several published studies observing an association between low serum selenium concentration and an increased relative risk of coronary heart disease, cardiomyopathies and myocardial infarction (Poltronieri et al., 1992). According to our results, it seems that addition of selenium to cardioplegic solutions significantly reduces ischemic injury and supplies better myocardial recovery in normothermic ischemic conditions. Although further studies are needed on the subject, we think that this beneficial effect of selenium can be
A comparative study on isolated guinea pig hearts was carried out to determine the role of selenium added cardioplegic solutions on postichemic and reperfusion injury. The hearts were mounted on a Langendorf perfusion apparatus and perfused with gassed KrebsHenseleit solution at 37°C. The hearts were arrested by one of the following cardioplegic solutions: (a) conventional crystalloid cardioplegia (K ÷ 20 mmol/1, control group); (b) selenium cardioplegia (K + 20 mol/1 +selenium 10-3mol/l, experimental group). After 20 min of normothermic ischemia the hearts were reperfused by the same buffer. Postichemic percentage changes of mechanical cardiac functions (heart rate and contractileforce) were compared between the groups. According to our results it seems that addition of selenium to cardioplegic solutions significantly improves cardiac recovery and decreases postischemic myocardial injury.
CONCLUSION In conclusion it can be argued that addition of 10 -3 mol/l, to classical cardioplegic solutions significantly improves myocardial recovery from ischemic cellular injury. selenium,
REFERENCES
Burk R. F. (1978) Selenium in nutrition. Worm Rev. Nutr. Diet 30, 88-106. Johansen J. V., Chiantella V., Faust K. B., Johnston W., McCain B. I., Hartman M., Mills S. A., Hester T. O. and CordeU A. R. (1988) Myocardial protection with blood cardioplegia in ischemically injured hearts: reduction of reoxygenation injury with allopurinol. Ann. Thorac. Surg. 45, 319-326. Menashe P., Grousset C. and Gaudel Y. (1988) Enhancement of cardioplegic protection with the free-radical scawenger peroxidase. Circulation 74, (Suppl. 3), 138-143.
Selenium cardioplegia Omar B. A., Hanson A. K., Bose S. K. and McCord J. M. (1991) Ischemic preconditioning is not mediated by free radicals in the isolated rabbit heart. Free Rad. Biol. Med. 11, 517-520. Osier O. and Prellwitz W. (1990) Selenium and cardiovascular disease. Biol. Trace Elem. Res. 24, 91-103. Poltronieri R., Cevese A. and Sbarbati A. (1992) Protective effect of selenium in cardiac ischemia and reperfusion. Cardioscience 3, 155-160. Ringstad J., Jacobsen B. K., Thomassen Y. and Thelle D. S. (1987) The Tromso heart study: serum selenium and risk of myocardial infarction a nested case control study. J. Epidemiol. Commun. Health 41, 329-332.
1497
Rotruck J., Ganther H., Swanson A., Hafeman D. and Hoekstra W. (1973) Selenium: biochemical role as a component of glutathione peroxidase. Science 179, 588-590. Salonen J. T. and Huttunen J. K. (1986) Selenium in cardiovascular diseases. Ann. Clin. Res. 18, 30-35. Salonen J. T., Alfthan G., Huttunen J. K., Pikkarainen J. and Puska P. (1982) Association between cardiovascular death and myocardial infarction and serum selenium in a matched pair longitudinal study. Lancet 175-179. Schoene N. W., Morris V. C. and Levander O. A. (1984) Effects of selenium deficiency on aggregation and thromboxane formation in rat platelets. Fedn. Proc. 43, 477-483.
Pergamon
0306-3623(94)E0096-5
Gen. Pharmac. Vol. 25, No. 7, pp. 1493-1497, 1994 Copyright© 1994ElsevierScienceLtd Printed in Great Britain.All rights reserved 0306-3623/94 $7.00+ 0.00
The Effect of Selenium Added Cardioplegia in Guinea Pigs HALiM SONCUL*, O~UZ TATLICAN, VELiT HALiT, ESER OZ, VOLKAN SINCI, ERGUN SALMAN, LEVENT GOKGOZ, NURTEN T1SIRKOZKAN and ALI ERSOZ Departments of Cardiovascular Surgery and Biochemistry, Gazi University Medical Faculty, Ankara, Turkey (Received 28 January 1994)
Abstract--1. The aim of the study was to determine the effect of selenium added cardioplegic solutions on postischemic myocardial recovery. 2. The hearts were mounted on Langendorf perfusion apparatus and perfused with Krebs-Henseleit solution. The hearts were arrested by one of the following cardioplegic solutions; (a) K + 20 mmol/1 (control group); (b) K ÷ 20 mmol/l + selenium 10-3 mol/1 (experimental group). After 20 min of normothermic ischemia the hearts were reperfused by the same buffer. 3. Postischemic percentage changes of heart rate, contractile force and heart work were compared between the groups. 4. Addition of selenium to the cardioplegic solution significantly decreased the postischemic myocardial injury.
KeyWords:Selenium, cardioplegia, ischemic injury
INTRODUCTION Interest in the role of selenium in the pathogenesis of cardiovascular disease originated from observations of blood pressure changes, cardiomyopathy and sudden cardiac death in animals with dietary selenium deficiency (Burk, 1978). There are also a number of clinical, ecological and epidemiological studies investigating the relationship between the serum selenium concentration and ischemic cardiac disease in humans (Ringstad et al., 1987; Salonen et al., 1982; Oster et al., 1990). Selenium deficiency affects several cellular mechanisms that have been implicated in the pathogenesis of atherosclerosis. Selenium depletion is accompanied by a decrease in the activity of glutathione peroxidase, a selenium containing enzyme present in several tissues, including platelets, arterial walls and the heart (Salonen and Huttunen, 1986). This enzyme has very important functions in the removal of hydrogen peroxide and fatty acid hydroperoxides in the cell. Glutathione peroxidase may also influence prostaglandin and leukotriene metabolism in platelets and *To whom all correspondence should be addressed.
in other tissues. Therefore selenium is a part of a system that provides a means of defense against the accumulation of lipid peroxides and free radicals that damage cell membranes and macro molecules. There is still intensive interest in different cardioplegic solutions, techniques and cardioplegic additives for better myocardial protection during cardiac operations. Several studies have demonstrated that myocardial protection with cardioplegic solutions can be improved by adding agents to inhibit oxyradical production or to degrade the reactive species (Johansen et al., 1988; Menache et al., 1986). In this study we aimed to test the effect of selenium added to conventional cardioplegic solutions on postischemic cardiac recovery. MATERIALS AND M E T H O D S Animals and perfusion techniques Hearts were obtained from male guinea pigs (n = 24) weighing 330-440 g. All animals received human care in compliance with the "Principles of Laboratory Animal Care" formulated by the National Society for Medical Research and the "Guide for the Care and Use of Laboratory Animals" prepared by
1493
1494
HALiMSONCULet al.
the National Academy of Sciences and published by the National Institutes of Health (NIH Publication No. 80-23, revised 1978). The animals were anaesthetized by ether and given 200 units of heparin into the femoral vein. The hearts (1.8-2.4 g) were rapidly removed and cannulated via the aorta. They were then mounted on a modified Langendorf perfusion apparatus and perfused by a gassed (O2 95%, CO2 5%) Krebs-Henseleit solution at a rate of 10 ml/min, at 37°C. The composition of the solution was as follows (in raM/l) NaHCO3, 25; NaCI, 118; KH2PO4, 1.2; KCI, 4.8; MgSO4, 1.2; CaC12, 1.2; and glucose, 11.1. Protocol
After 15 min the heart had begun to work, we recorded the contractile force (mm/g) and the heart rate (beats/min). The hearts were arrested by introduction of one of the cardioplegic solutions (K ÷ 20mmol/1 in the control group (Plegisol), K ÷ 20 mmol/1 and Selenium 10 3mol/l in the experimental group) from the aortic root for 3 rain (at a rate of 10 ml/min at 4°C). During the ischemic period the hearts were kept at normothermic conditions. After 20 min of ischemia the reperfusion was begun by the same buffer at 37°C. The ventricular contractilforce and heart rate were recorded again just after the ischemic period and also at the 20th min of reperfusion. (Fig. 1) Calculations
The following calculations were made:
Percentage recovery of heart rate = Postischemic heart rate x 100 Preischemic heart rate Percentage recovery of contractile force-Postischemic contractions × 100 Preischemic contractions Percentage recovery of heart work = Postischemic heart rate x postischemic contractions x 100 Preischemic heart rate x preischemic contractions Data and statistics
Ventricular contractileforce (mm/g) and heart rate (beat/min) were recorded through an isometric force transducer (UGO BASILE 7004), (a resting tension of 5 g was applied) connected to a (UGO BASILE 7050) microdynomorneter. The results are presented as mean and standard error of the mean. Overall significance of differences between groups was determined by t-test using the "Microsoft Excel 4.0" PC program. RESULTS The mean percentage change of the heart rate was significantly higher in the selenium group after the ischemic period (102% vs 83%, P = 0.06) and also after the reperfusion (110% vs 89%, P = 0.02).
Perfusion with Krebs solution
Pump
~
I
[....Transducer .......................
5 grams
Fig. 1. Experimental design. Data were recorded just before the ischemia, after the ischemic period and after 20 min of reperfusion.
Selenium cardioplegia
1495
Heart rate
125
~o 100
75
5~ PreAfter reperfusion
Contractile force
120
IO0
,.~
80
6C
4~
PreAfter reperfusion
Heart work
120
I00 ¢J
~*
80
60
40 Pre-i After reperfusioa Fig. 2. Comparison of the percentage changes of heart rate, contractile force and heart work in groups. 5~" indicates a statistical difference (P < 0.05) between the two groups, ,¢~;~ indicates a statistical difference (P < 0.005) between the two groups, ~ indicates a significant difference between the indicated value and pre-ischemic value.
1496
HALiMSONCULet al. Table I. Percentagechanges of mechanical parametersbetween the groups Heart rate
Contractile force
Heart work
Control Pre-ischemic Post-ischemic After reperfusion
100% 83.1% ± 8.4% 89.0% ± 8.9%
100% 60.7% + 6.3% 54.0% +_ 7.4%
100% 51.1% + 4.8% 47.7% + 6.9%
Selenium Pre-ischemic Post-ischemic After reperfusion
100 % 102% +_9.4% 110.0% +_ 12.5%
100% 86.6% _+ 7.3% 91.0% +_ 10.0%
100 % 84.3% _+6.2% 92.1% ± 11.5%
Values are percentagechange accordingto the pre-ischemicvalues(mean+ SEM).
For the contractile force, again we achieved similar results. The mean percentage change of the contractile force was significantly higher in the selenium group after the ischemia (86% v 60%, P = 0.03) and after the reperfusion (91% v 54%, P = 0.05). For the heart work parameter, which is defined by us (heart rate × contractile force), the differences between the groups were again statistically significant both after ischemia (P = 0.0005) and after reperfusion (P = 0.002) (Fig. 2, Table 1).
explained by its role in the glutathione peroxidase system.
DISCUSSION
SUMMARY
In hearts with relatively normal preoperative ventricular performance, hypothermic potassium cardioplegia provides adequate protection during aortic-clamping. However, the same cardioplegic strategies do not adequately protect hearts with antecedent global or regional ischemia and when cardioplegic arrest is prolonged. A number of reports suggest that the pathogenesis of cardiac ischemic injury may be partly ascribed to the production of activated oxygen species (Johansen et al., 1988; Omar et al., 1991). Therefore, much interest has been focused on the trace element selenium, which is an essential prosthetic group for the enzyme glutathione peroxidase. This enzyme reduces lipid hydroperoxides to the corresponding lipid alcohols (or water), thereby possibly protecting the epithelium from oxidative damage (Rotruck et al., 1973). Glutathione peroxidase may also influence the synthesis of prostacyclin, an agent protective against platelet aggregation (Schoene et al., 1984). There are several published studies observing an association between low serum selenium concentration and an increased relative risk of coronary heart disease, cardiomyopathies and myocardial infarction (Poltronieri et al., 1992). According to our results, it seems that addition of selenium to cardioplegic solutions significantly reduces ischemic injury and supplies better myocardial recovery in normothermic ischemic conditions. Although further studies are needed on the subject, we think that this beneficial effect of selenium can be
A comparative study on isolated guinea pig hearts was carried out to determine the role of selenium added cardioplegic solutions on postichemic and reperfusion injury. The hearts were mounted on a Langendorf perfusion apparatus and perfused with gassed KrebsHenseleit solution at 37°C. The hearts were arrested by one of the following cardioplegic solutions: (a) conventional crystalloid cardioplegia (K ÷ 20 mmol/1, control group); (b) selenium cardioplegia (K + 20 mol/1 +selenium 10-3mol/l, experimental group). After 20 min of normothermic ischemia the hearts were reperfused by the same buffer. Postichemic percentage changes of mechanical cardiac functions (heart rate and contractileforce) were compared between the groups. According to our results it seems that addition of selenium to cardioplegic solutions significantly improves cardiac recovery and decreases postischemic myocardial injury.
CONCLUSION In conclusion it can be argued that addition of 10 -3 mol/l, to classical cardioplegic solutions significantly improves myocardial recovery from ischemic cellular injury. selenium,
REFERENCES
Burk R. F. (1978) Selenium in nutrition. Worm Rev. Nutr. Diet 30, 88-106. Johansen J. V., Chiantella V., Faust K. B., Johnston W., McCain B. I., Hartman M., Mills S. A., Hester T. O. and CordeU A. R. (1988) Myocardial protection with blood cardioplegia in ischemically injured hearts: reduction of reoxygenation injury with allopurinol. Ann. Thorac. Surg. 45, 319-326. Menashe P., Grousset C. and Gaudel Y. (1988) Enhancement of cardioplegic protection with the free-radical scawenger peroxidase. Circulation 74, (Suppl. 3), 138-143.
Selenium cardioplegia Omar B. A., Hanson A. K., Bose S. K. and McCord J. M. (1991) Ischemic preconditioning is not mediated by free radicals in the isolated rabbit heart. Free Rad. Biol. Med. 11, 517-520. Osier O. and Prellwitz W. (1990) Selenium and cardiovascular disease. Biol. Trace Elem. Res. 24, 91-103. Poltronieri R., Cevese A. and Sbarbati A. (1992) Protective effect of selenium in cardiac ischemia and reperfusion. Cardioscience 3, 155-160. Ringstad J., Jacobsen B. K., Thomassen Y. and Thelle D. S. (1987) The Tromso heart study: serum selenium and risk of myocardial infarction a nested case control study. J. Epidemiol. Commun. Health 41, 329-332.
1497
Rotruck J., Ganther H., Swanson A., Hafeman D. and Hoekstra W. (1973) Selenium: biochemical role as a component of glutathione peroxidase. Science 179, 588-590. Salonen J. T. and Huttunen J. K. (1986) Selenium in cardiovascular diseases. Ann. Clin. Res. 18, 30-35. Salonen J. T., Alfthan G., Huttunen J. K., Pikkarainen J. and Puska P. (1982) Association between cardiovascular death and myocardial infarction and serum selenium in a matched pair longitudinal study. Lancet 175-179. Schoene N. W., Morris V. C. and Levander O. A. (1984) Effects of selenium deficiency on aggregation and thromboxane formation in rat platelets. Fedn. Proc. 43, 477-483.