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The Effect of Allopurinol Pretreatment Before Detorting Testicular Torsion
0022-534 7/94/1516-1715$03.00/0 VoL 151, 1715-1717, June 1994
THE JOURNAL OF UROLOGY
Copyright© 1394 by AMERICAN UROLOGICAL ASSOCIATION, INC.
Printed in U.S.A.
THE EFFECT OF ALLOPURINOL PRETREATMENT BEFORE DETORTING TESTICULAR TORSION FEZA M. AKGUR,* KAMER KILINC, TANJU AKTUG AND MUSTAFA OLGUNER From the Department of Pediatric Surgery, Medical Faculty, Dokuz Eylul University, lzmir and the Department of Biochemistry, Medical Faculty, Hacettepe University, Ankara, Turkey
ABSTRACT
The resumption of blood flow to organs following ischemia may cause a further increase in tissue damage through an increase in peroxidation of lipids in cell membranes. An experimental study was conducted to investigate the prevention of reperfusion injury after testicular torsion through changes in the lipid peroxide content of the testis. Adult male albino rats were divided into 11 groups, each containing 10 rats. One group served to determine base values of the lipid peroxide content of the testis and kidney; 3 groups were subjected to unilateral testicular torsion lasting 1, 3 and 5 hours; 3 groups were subjected to detorsion following torsion lasting 1, 3 and 5 hours; 3 groups were treated with allopurinol before detorsion following torsion lasting 1, 3 and 5 hours; and 1 group underwent sham operation as a control. Thiobarbituric acid reactive products of lipid peroxidation (TBAR) were assessed in testicular and renal tissues. Testicular torsion caused a significant increase in TBAR in the testis (p < 0.01), but not in the kidneys. Detorsion caused a further significant increase in testicular TBAR (p < 0.01). Pretreatment with allopurinol prevented this further increase (p < 0.01). It is concluded that, biochemically, reperfusion injury occurs in the testis following detorsion after testicular torsion of 720° lasting as long as 5 hours. Pretreatment with allopurinol before detorsion prevents such reperfusion injury. KEY WoRDS: testis, torsion, free radicals, reperfusion injury
Treatment of testicular torsion by detorsion may further damage the testis. With the resumption of blood flow, oxygen is supplied which is necessary for the conversion of hypoxanthine (an ATP degradation product) to uric acid in the presence of the enzyme xanthine oxidase. 1- 3 During this conversion, abundant amounts of free oxygen radicals are produced. 1- 3 These free radicals react with lipids in the cell and mitochondrial membranes forming lipid peroxides. 1- 3 Peroxidation of the lipids in membranes changes membrane permeability or disrupts membrane integrity and thus cell integrity. 1- 3 This cascade of events is known as posthypoxic-reoxygenation injury or by the more widely used reperfusion injury. 1 The lipid peroxide content of tissues can be determined by several methods. One is the determination of thiobarbituric acid reactive products of lipid peroxidation (TBAR).4 Reperfusion injury has been studied in the testis through changes in the TBAR content of the testis and has been shown to occur after detorsion of testicular torsion of 720° lasting less than 6 hours. 5 ' 6 Prevention of reperfusion injury the use of several enzymes and drugs is possible and ensures that adequate blood drug levels are reached prior to resumption of blood flow. 1 Prevention of reperfusion injury has been studied, with conflicting results, through assessment of histopathological changes after testicular torsion. 7, 8 An experimental study was conducted to investigate the prevention of reperfusion injury after testicular torsion through biochemical changes. MATERIALS AND METHODS
Study groups consisted of 110 adult male albino rats [Rattus norvegicus (Wistar) (Homogeneity= 93.75%)] obtained from Istanbul University, Experimental Research Center. Rats were divided into 11 groups, each containing 10 rats. All surgical procedures were performed under intraperitoneal one-shot ketamine (30 mg./kg.) anesthesia. Torsion, detorsion and sham Accepted for publication December 10, 1993. * Requests for reprints: Dokuz Eylul Universitesi, Tip Fakultesi <;ocuk Cerrahisi Anabilim Dali, Inciralti 35340 Izmir, Turkey.
operations were all performed through standard ilioinguinal incisions. Torsion was created by rotating the left testis 720° clockwise. Torsion was maintained by fixing the testis to the scrotum with a silk suture through the tunica albuginea. During sham operations the testis was brought through the incision and replaced, and a silk suture was placed through the tunica albuginea. After each surgical intervention the incision was closed. The rats were allowed to recover from anesthesia and were left free in their cages. They were reanesthetized for the following manipulation. At the end of the experiments, left orchiectomies and right nephrectomies were performed. Group 1 (base value group). After anesthesia the aforementioned organs were harvested to determine basal values of lipid peroxides in these organs. Groups 2, 3, 4 (Torsion groups). The aforementioned organs were harvested at the end of 1, 3 and 5 hours of testicular torsion. TABLE
1. Thiobarbituric acid reactive substances of lipid peroxidation
(TEAR) values in testes. (Mean ± SD) Groups Basal 1 h. torsion 3 hrs, torsion 5 hrs. torsion Detorsion of torsion for 1 hr. Detorsion of torsion for 3 hrs, Detorsion of torsion for 5 hrs. Detorsion of torsion for 1 hr. with allopurinol pretreatment Detorsion of torsion for 3 hrs. with allopurinol pretreatment Detorsion of torsion for 5 hrs, with allopurinol pretreatment Sham operation
TBAR* 81.30 141.20 149.30 134.14 219.30 242. 75 201.50 110.50
± ± ± ± ± ± ± ±
9.64 21.51 t 35.12t 30.41 t 42.08t:j: 30.07t:j: 24.04 tt 32.60t§ 11
177.63 ± 34.32t§ 11 146.13 ± 20.50t§ 11 84.30 ± 10.87
* nmol./gm. wet tissue.
tp<
0.01 compared with base-value group.
+p < 0.01 compared with torsion group of equal duration.
§ p < 0.01 compared with detorsion group without pretreatment of equal duration. II p > 0.05 compared with torsion group of equal duration.
1715
1716
ALLOPURINOL AND TESTICULAR TORSION
Thiobarbituric acid reactive substances of lipid peroxidation (TEAR) values in kidneys. (Mean ± 1 SD) Groups TBAR*t 176.80 ± 31.01 Basal 1 hr. torsion 155.60 ± 29.08 186.00 ± 40.07 3 hrs. torsion TABLE 2.
5 hrs. torsion Detorsion of torsion for 1 hr. Detorsion of torsion for 3 hrs. Detorsion of torsion for 5 hrs. Detorsion of torsion for 1 hr. with allopurinol pretreatment Detorsion of torsion for 3 hrs. with allopurinol pretreatment Detorsion of torsion for 5 hrs. with allopurinol pretreatment Sham operation
147.00 ± 166.60 ± 132.25 ± 191.25 ± 177.40 ±
29.46 27 .02 34.33 20.85 16.83
183.75 ± 32.65 182.25 ± 28.33 168.65 ± 33.15
* nmol/gm. wet tissue.
t The difference between groups are not statistically significant (p > 0.05).
Groups 5, 6, 7 (detorsion groups). Detorsion was carried out after torsion lasting 1, 3 and 5 hours. The aforementioned organs were harvested 2 hours after detorsion in all groups. Groups 8, 9, 10 (detorsion groups with allopurinol pretreatment). Allopurinol (200 mg./kg.) was injected intraperitoneally 30 minutes prior to detorsion. Detorsion was carried out after torsion lasting 1, 3 and 5 hours. The aforementioned organs were harvested 2 hours after detorsion in all groups. Group 11 (two-sham operation control group). Sham operation was repeated 1 hour after the first sham operation. The aforementioned organs were harvested 2 hours after the second sham operation. All organs were placed in glass bottles with rubber caps, labeled and stored in a deep freeze. Thiobarbituric acid reactive products of lipid peroxidation were determined in tissues. ANOVA was used for statistical analysis of the data among groups. Multiple comparisons were made using Tukey's procedure. Biochemical determinations. Tissues were homogenized in 150 mM. ice-cold KCl to make a 10% homogenate, using a glass Teflon homogenizer. Two ml. of this homogenate was immediately pipetted into a tube containing 2 ml. of cold 8% (v/v) HC10 4 • The mixture was shaken vigorously and kept cold until centrifuged. Determination of lipid peroxides. Lipid peroxides in tissues were determined by the method of Uchiama and Mihara. 9 Three ml. of 1 % phosphoric acid and 1 ml. of 0.6% TBA solution were added to 0.5 ml. of 10% tissue homogenate pipetted into a tube. The mixture was heated in boiling water for 45 minutes. After cooling, the color was extracted into 4 ml. of the n-butanol and the absorbance was measured (t = 1.56 x 105 M.- 1 cm.- 1 ). The amounts of lipid peroxides were calculated as thiobarbituric ?.cid reactive products of lipid peroxidation and reported as nanomole per gram of wet tissue. RESULTS
Basal intratesticular and intrarenal thiobarbituric acid reactive products of lipid peroxidation (TBAR) values are shown in tables 1 and 2. The values obtained from the sham operation control group organs are not significantly different from base values (p > 0.05) (tables 1 and 2). Compared with basal values, TBAR values obtained from the testicular torsion groups are significantly higher in the testes (p < 0.01) but not statistically different in the kidneys (p > 0.05) (tables 1 and 2). Compared with values obtained from torsion of equal duration, TBAR values obtained after detorsion of equal duration are further increased significantly in the testes (p < 0.01) but not statistically different in the kidneys (p > 0.05) (tables 1 and 2). Compared with values obtained from detorsion groups of
equal duration, TBAR values obtained from detorsion after allopurinol pretreatment of equal duration are significantly lower in the testes (p < 0.01) but not statistically different in the kidneys (p > 0.05) (tables 1 and 2). DISCUSSION
Reperfusion injury has been studied through changes in the lipid peroxide content of the testis and has been shown to occur after testicular torsion of 72Q° lasting 1 and 2 hours 5 but not after 720° testicular torsion lasting more than 6 hours. 6 The present study showed that testicular torsion causes an increase in lipid peroxidation, and detorsion causes a further increase in lipid peroxidation. Thus we may say that reperfusion injury does occur after 720° testicular torsion lasting 1, 3 and 5 hours. Prevention of reperfusion injury is possible using several enzymes such as superoxide dismutase (SOD) and drugs such as allopurinol to ensure that adequate blood drug levels are reached before resumption of blood flow. 1- 3 Superoxide dismutase is an enzyme normally found in tissues and catalyzes the reaction with scavenging free oxygen radicals. 2 The pharmacologic activity of allopurinol and its metabolites, such as oxypurinol, is through inhibition of the enzyme xanthine oxidase.2 Akhter et al. studied prevention of reperfusion injury histopathologically in testicular torsion. 7 They found that pretreatment with heparin, oxypurinol and polyethylene glycolsuperoxide dismutase (PEG-SOD) resulted in significant protection (p < 0.01) from reperfusion injury after 1 hour of torsion and pretreatment with oxypurinol resulted in limited but still statistically significant protection (p < 0.05) after 4 hours' torsion. 7 Pretreatment did not protect animals subjected to 8 and 24 hours of torsion. 7 On the other hand Greenstein et al. also studied prevention of reperfusion injury using PEG-SOD pretreatment in 720° testicular torsion lasting 3 hours but did not find any statistically significant histopathologic difference between the treatment and control groups. 8 The present study has shown that pretreatment with allopurinol prevents further increase in lipid peroxidation caused by detorsion; thus prevention of reperfusion injury occurs after testicular torsion lasting as long as 5 hours. Our results are consistent with the histopathologic findings of Akhter et al. Greenstein et al. 8 commented that their results coincide with other research studying prevention of reperfusion injury in the testis conducted by Bergh et al. 10 These workers also studied prevention reperfusion injury using SOD plus catalase and did not find any histopathologic changes between treated and untreated groups. 10 But Bergh et al.'s experimental model was not testicular torsion; they ligated the testicular artery instead of torsing the testis. 10 Ischemia induced by artery ligation is a model of global ischemia. Testicular torsion of 720° initially occludes the veins but not the arteries and thus represents partial ischemia in the early periods of torsion. Organs vary in their tolerance of ischemia. 2·3 In organs such as the heart and skin, free radical scavengers are effective in preventing reperfusion injury after global ischemia. 2·3 However, in the intestine, free radical scavengers fail to prevent reperfusion injury after global ischemia but do prevent such injury after brief periods of partial ischemia. 2·3 The testis may resemble the intestine in its response to ischemia. Thus these two studies are not comparable. It is concluded that, biochemically, reperfusion injury occurs in the testis following detorsion after 720° testicular torsion lasting as long as 5 hours. Pretreatment with allopurinol before detorsion prevents such injury. Acknowledgment. We would like to thank Professor Dr, Ataman Gure and Assistant Professor Dr. Sedef Gidener for their help during this study. REFERENCES 1. Bulkley, G. B.: Free radical-mediated reperfusion injury: a selective review. Br. J. Cancer, suppl., 55: 66, 1987.
ALLOPURINOL AND TESTICULAR TORSION
2. Reilly, i) M., Schilier, I-L J. and Buikley, G. R: Pharmacoiogic approach to tissue injury mediated by free radicals and other reactive oxygen metabolites. Am. J. Surg., HH: 488, 1992. 3. Feher, J., Csomos, G. and Vereckei, A.: Free radical reactions in medicine. Berlin: Springer-Verlag, 1987. 4. Kagan, V. K: Lipid peroxidation in biomembranes. Boca Raton, Florida: CRC Press, 198R 5. Akgur, F. M., Kilin9, K. and Aktug, T.: Reperfusion injury after detorsion of unilateral testicular torsion. UroL Res., 21: 395, 1993. 6. Akgur, F. M., Kilin\;, K., Tanyel, F. C., Biiyiikpamuki;:u, N. and Hi9sonmez, A.: Ipsilateral and contralateral biochemical changes after unilateral testicular torsion and detorsion. Urology, (in press), 1994. 7. Akhter, S., Sridher, S., Katlowitz, N. M., Lindsay, K. G., Lamy,
1717
Y., Butt, K. M., Cunningham, J. N. and Wise, G. J.: Immune response to testicular ischemia and reperfusion. J. Urnl., part 2, 143: 262A, abstract 296, 1990. 8. Greenstein, A., Smith-Harrison, L. L, Wakely, P. E., Kololgi, S.,Salzberg, A. D. and Koontz, W.W., Jr.: The effect of polyethylene glycol-superoxide dismutase administration on histologic damage following spermatic cord torsion. J. Urol., 148: 639, 1992. 9. Uchiama, M. and Mihara, M.: Determination of malonaldehyde precursor in tissues by thiobarbituric acid test. Anal. Biochem., 86: 271, 1977. 10. Bergh, A., Damber, J.E. and Marklund, S. E.: Morphologic changes induced by short term ischemia in rat testis are not affected by treatment with superoxide dismutase or catalase. J. Androl., 9: 15, 1988.
THE JOURNAL OF UROLOGY
Copyright© 1394 by AMERICAN UROLOGICAL ASSOCIATION, INC.
Printed in U.S.A.
THE EFFECT OF ALLOPURINOL PRETREATMENT BEFORE DETORTING TESTICULAR TORSION FEZA M. AKGUR,* KAMER KILINC, TANJU AKTUG AND MUSTAFA OLGUNER From the Department of Pediatric Surgery, Medical Faculty, Dokuz Eylul University, lzmir and the Department of Biochemistry, Medical Faculty, Hacettepe University, Ankara, Turkey
ABSTRACT
The resumption of blood flow to organs following ischemia may cause a further increase in tissue damage through an increase in peroxidation of lipids in cell membranes. An experimental study was conducted to investigate the prevention of reperfusion injury after testicular torsion through changes in the lipid peroxide content of the testis. Adult male albino rats were divided into 11 groups, each containing 10 rats. One group served to determine base values of the lipid peroxide content of the testis and kidney; 3 groups were subjected to unilateral testicular torsion lasting 1, 3 and 5 hours; 3 groups were subjected to detorsion following torsion lasting 1, 3 and 5 hours; 3 groups were treated with allopurinol before detorsion following torsion lasting 1, 3 and 5 hours; and 1 group underwent sham operation as a control. Thiobarbituric acid reactive products of lipid peroxidation (TBAR) were assessed in testicular and renal tissues. Testicular torsion caused a significant increase in TBAR in the testis (p < 0.01), but not in the kidneys. Detorsion caused a further significant increase in testicular TBAR (p < 0.01). Pretreatment with allopurinol prevented this further increase (p < 0.01). It is concluded that, biochemically, reperfusion injury occurs in the testis following detorsion after testicular torsion of 720° lasting as long as 5 hours. Pretreatment with allopurinol before detorsion prevents such reperfusion injury. KEY WoRDS: testis, torsion, free radicals, reperfusion injury
Treatment of testicular torsion by detorsion may further damage the testis. With the resumption of blood flow, oxygen is supplied which is necessary for the conversion of hypoxanthine (an ATP degradation product) to uric acid in the presence of the enzyme xanthine oxidase. 1- 3 During this conversion, abundant amounts of free oxygen radicals are produced. 1- 3 These free radicals react with lipids in the cell and mitochondrial membranes forming lipid peroxides. 1- 3 Peroxidation of the lipids in membranes changes membrane permeability or disrupts membrane integrity and thus cell integrity. 1- 3 This cascade of events is known as posthypoxic-reoxygenation injury or by the more widely used reperfusion injury. 1 The lipid peroxide content of tissues can be determined by several methods. One is the determination of thiobarbituric acid reactive products of lipid peroxidation (TBAR).4 Reperfusion injury has been studied in the testis through changes in the TBAR content of the testis and has been shown to occur after detorsion of testicular torsion of 720° lasting less than 6 hours. 5 ' 6 Prevention of reperfusion injury the use of several enzymes and drugs is possible and ensures that adequate blood drug levels are reached prior to resumption of blood flow. 1 Prevention of reperfusion injury has been studied, with conflicting results, through assessment of histopathological changes after testicular torsion. 7, 8 An experimental study was conducted to investigate the prevention of reperfusion injury after testicular torsion through biochemical changes. MATERIALS AND METHODS
Study groups consisted of 110 adult male albino rats [Rattus norvegicus (Wistar) (Homogeneity= 93.75%)] obtained from Istanbul University, Experimental Research Center. Rats were divided into 11 groups, each containing 10 rats. All surgical procedures were performed under intraperitoneal one-shot ketamine (30 mg./kg.) anesthesia. Torsion, detorsion and sham Accepted for publication December 10, 1993. * Requests for reprints: Dokuz Eylul Universitesi, Tip Fakultesi <;ocuk Cerrahisi Anabilim Dali, Inciralti 35340 Izmir, Turkey.
operations were all performed through standard ilioinguinal incisions. Torsion was created by rotating the left testis 720° clockwise. Torsion was maintained by fixing the testis to the scrotum with a silk suture through the tunica albuginea. During sham operations the testis was brought through the incision and replaced, and a silk suture was placed through the tunica albuginea. After each surgical intervention the incision was closed. The rats were allowed to recover from anesthesia and were left free in their cages. They were reanesthetized for the following manipulation. At the end of the experiments, left orchiectomies and right nephrectomies were performed. Group 1 (base value group). After anesthesia the aforementioned organs were harvested to determine basal values of lipid peroxides in these organs. Groups 2, 3, 4 (Torsion groups). The aforementioned organs were harvested at the end of 1, 3 and 5 hours of testicular torsion. TABLE
1. Thiobarbituric acid reactive substances of lipid peroxidation
(TEAR) values in testes. (Mean ± SD) Groups Basal 1 h. torsion 3 hrs, torsion 5 hrs. torsion Detorsion of torsion for 1 hr. Detorsion of torsion for 3 hrs, Detorsion of torsion for 5 hrs. Detorsion of torsion for 1 hr. with allopurinol pretreatment Detorsion of torsion for 3 hrs. with allopurinol pretreatment Detorsion of torsion for 5 hrs, with allopurinol pretreatment Sham operation
TBAR* 81.30 141.20 149.30 134.14 219.30 242. 75 201.50 110.50
± ± ± ± ± ± ± ±
9.64 21.51 t 35.12t 30.41 t 42.08t:j: 30.07t:j: 24.04 tt 32.60t§ 11
177.63 ± 34.32t§ 11 146.13 ± 20.50t§ 11 84.30 ± 10.87
* nmol./gm. wet tissue.
tp<
0.01 compared with base-value group.
+p < 0.01 compared with torsion group of equal duration.
§ p < 0.01 compared with detorsion group without pretreatment of equal duration. II p > 0.05 compared with torsion group of equal duration.
1715
1716
ALLOPURINOL AND TESTICULAR TORSION
Thiobarbituric acid reactive substances of lipid peroxidation (TEAR) values in kidneys. (Mean ± 1 SD) Groups TBAR*t 176.80 ± 31.01 Basal 1 hr. torsion 155.60 ± 29.08 186.00 ± 40.07 3 hrs. torsion TABLE 2.
5 hrs. torsion Detorsion of torsion for 1 hr. Detorsion of torsion for 3 hrs. Detorsion of torsion for 5 hrs. Detorsion of torsion for 1 hr. with allopurinol pretreatment Detorsion of torsion for 3 hrs. with allopurinol pretreatment Detorsion of torsion for 5 hrs. with allopurinol pretreatment Sham operation
147.00 ± 166.60 ± 132.25 ± 191.25 ± 177.40 ±
29.46 27 .02 34.33 20.85 16.83
183.75 ± 32.65 182.25 ± 28.33 168.65 ± 33.15
* nmol/gm. wet tissue.
t The difference between groups are not statistically significant (p > 0.05).
Groups 5, 6, 7 (detorsion groups). Detorsion was carried out after torsion lasting 1, 3 and 5 hours. The aforementioned organs were harvested 2 hours after detorsion in all groups. Groups 8, 9, 10 (detorsion groups with allopurinol pretreatment). Allopurinol (200 mg./kg.) was injected intraperitoneally 30 minutes prior to detorsion. Detorsion was carried out after torsion lasting 1, 3 and 5 hours. The aforementioned organs were harvested 2 hours after detorsion in all groups. Group 11 (two-sham operation control group). Sham operation was repeated 1 hour after the first sham operation. The aforementioned organs were harvested 2 hours after the second sham operation. All organs were placed in glass bottles with rubber caps, labeled and stored in a deep freeze. Thiobarbituric acid reactive products of lipid peroxidation were determined in tissues. ANOVA was used for statistical analysis of the data among groups. Multiple comparisons were made using Tukey's procedure. Biochemical determinations. Tissues were homogenized in 150 mM. ice-cold KCl to make a 10% homogenate, using a glass Teflon homogenizer. Two ml. of this homogenate was immediately pipetted into a tube containing 2 ml. of cold 8% (v/v) HC10 4 • The mixture was shaken vigorously and kept cold until centrifuged. Determination of lipid peroxides. Lipid peroxides in tissues were determined by the method of Uchiama and Mihara. 9 Three ml. of 1 % phosphoric acid and 1 ml. of 0.6% TBA solution were added to 0.5 ml. of 10% tissue homogenate pipetted into a tube. The mixture was heated in boiling water for 45 minutes. After cooling, the color was extracted into 4 ml. of the n-butanol and the absorbance was measured (t = 1.56 x 105 M.- 1 cm.- 1 ). The amounts of lipid peroxides were calculated as thiobarbituric ?.cid reactive products of lipid peroxidation and reported as nanomole per gram of wet tissue. RESULTS
Basal intratesticular and intrarenal thiobarbituric acid reactive products of lipid peroxidation (TBAR) values are shown in tables 1 and 2. The values obtained from the sham operation control group organs are not significantly different from base values (p > 0.05) (tables 1 and 2). Compared with basal values, TBAR values obtained from the testicular torsion groups are significantly higher in the testes (p < 0.01) but not statistically different in the kidneys (p > 0.05) (tables 1 and 2). Compared with values obtained from torsion of equal duration, TBAR values obtained after detorsion of equal duration are further increased significantly in the testes (p < 0.01) but not statistically different in the kidneys (p > 0.05) (tables 1 and 2). Compared with values obtained from detorsion groups of
equal duration, TBAR values obtained from detorsion after allopurinol pretreatment of equal duration are significantly lower in the testes (p < 0.01) but not statistically different in the kidneys (p > 0.05) (tables 1 and 2). DISCUSSION
Reperfusion injury has been studied through changes in the lipid peroxide content of the testis and has been shown to occur after testicular torsion of 72Q° lasting 1 and 2 hours 5 but not after 720° testicular torsion lasting more than 6 hours. 6 The present study showed that testicular torsion causes an increase in lipid peroxidation, and detorsion causes a further increase in lipid peroxidation. Thus we may say that reperfusion injury does occur after 720° testicular torsion lasting 1, 3 and 5 hours. Prevention of reperfusion injury is possible using several enzymes such as superoxide dismutase (SOD) and drugs such as allopurinol to ensure that adequate blood drug levels are reached before resumption of blood flow. 1- 3 Superoxide dismutase is an enzyme normally found in tissues and catalyzes the reaction with scavenging free oxygen radicals. 2 The pharmacologic activity of allopurinol and its metabolites, such as oxypurinol, is through inhibition of the enzyme xanthine oxidase.2 Akhter et al. studied prevention of reperfusion injury histopathologically in testicular torsion. 7 They found that pretreatment with heparin, oxypurinol and polyethylene glycolsuperoxide dismutase (PEG-SOD) resulted in significant protection (p < 0.01) from reperfusion injury after 1 hour of torsion and pretreatment with oxypurinol resulted in limited but still statistically significant protection (p < 0.05) after 4 hours' torsion. 7 Pretreatment did not protect animals subjected to 8 and 24 hours of torsion. 7 On the other hand Greenstein et al. also studied prevention of reperfusion injury using PEG-SOD pretreatment in 720° testicular torsion lasting 3 hours but did not find any statistically significant histopathologic difference between the treatment and control groups. 8 The present study has shown that pretreatment with allopurinol prevents further increase in lipid peroxidation caused by detorsion; thus prevention of reperfusion injury occurs after testicular torsion lasting as long as 5 hours. Our results are consistent with the histopathologic findings of Akhter et al. Greenstein et al. 8 commented that their results coincide with other research studying prevention of reperfusion injury in the testis conducted by Bergh et al. 10 These workers also studied prevention reperfusion injury using SOD plus catalase and did not find any histopathologic changes between treated and untreated groups. 10 But Bergh et al.'s experimental model was not testicular torsion; they ligated the testicular artery instead of torsing the testis. 10 Ischemia induced by artery ligation is a model of global ischemia. Testicular torsion of 720° initially occludes the veins but not the arteries and thus represents partial ischemia in the early periods of torsion. Organs vary in their tolerance of ischemia. 2·3 In organs such as the heart and skin, free radical scavengers are effective in preventing reperfusion injury after global ischemia. 2·3 However, in the intestine, free radical scavengers fail to prevent reperfusion injury after global ischemia but do prevent such injury after brief periods of partial ischemia. 2·3 The testis may resemble the intestine in its response to ischemia. Thus these two studies are not comparable. It is concluded that, biochemically, reperfusion injury occurs in the testis following detorsion after 720° testicular torsion lasting as long as 5 hours. Pretreatment with allopurinol before detorsion prevents such injury. Acknowledgment. We would like to thank Professor Dr, Ataman Gure and Assistant Professor Dr. Sedef Gidener for their help during this study. REFERENCES 1. Bulkley, G. B.: Free radical-mediated reperfusion injury: a selective review. Br. J. Cancer, suppl., 55: 66, 1987.
ALLOPURINOL AND TESTICULAR TORSION
2. Reilly, i) M., Schilier, I-L J. and Buikley, G. R: Pharmacoiogic approach to tissue injury mediated by free radicals and other reactive oxygen metabolites. Am. J. Surg., HH: 488, 1992. 3. Feher, J., Csomos, G. and Vereckei, A.: Free radical reactions in medicine. Berlin: Springer-Verlag, 1987. 4. Kagan, V. K: Lipid peroxidation in biomembranes. Boca Raton, Florida: CRC Press, 198R 5. Akgur, F. M., Kilin9, K. and Aktug, T.: Reperfusion injury after detorsion of unilateral testicular torsion. UroL Res., 21: 395, 1993. 6. Akgur, F. M., Kilin\;, K., Tanyel, F. C., Biiyiikpamuki;:u, N. and Hi9sonmez, A.: Ipsilateral and contralateral biochemical changes after unilateral testicular torsion and detorsion. Urology, (in press), 1994. 7. Akhter, S., Sridher, S., Katlowitz, N. M., Lindsay, K. G., Lamy,
1717
Y., Butt, K. M., Cunningham, J. N. and Wise, G. J.: Immune response to testicular ischemia and reperfusion. J. Urnl., part 2, 143: 262A, abstract 296, 1990. 8. Greenstein, A., Smith-Harrison, L. L, Wakely, P. E., Kololgi, S.,Salzberg, A. D. and Koontz, W.W., Jr.: The effect of polyethylene glycol-superoxide dismutase administration on histologic damage following spermatic cord torsion. J. Urol., 148: 639, 1992. 9. Uchiama, M. and Mihara, M.: Determination of malonaldehyde precursor in tissues by thiobarbituric acid test. Anal. Biochem., 86: 271, 1977. 10. Bergh, A., Damber, J.E. and Marklund, S. E.: Morphologic changes induced by short term ischemia in rat testis are not affected by treatment with superoxide dismutase or catalase. J. Androl., 9: 15, 1988.