123. Acute Post-Ischemic Treatment With Estrogen Receptor-Beta Agonist 2,3-Bis(4-Hydroxyphenyl)-Propionitrile Improves Myocardial Recovery

230

ASSOCIATION FOR ACADEMIC SURGERY AND SOCIETY OF UNIVERSITY SURGEONS—ABSTRACTS

deletion attenuates preconditioning and is not associated with compensatory upregulation of STAT-5 and-6 subtypes. Moreover, activation of STAT-5 and ⫺6 in KO hearts following ischemic challenge does not provide functional compensation for the loss of STAT-3. JAK-STAT signaling via STAT-3 is essential for effective ischemic preconditioning and may represent an important target for pharmacologic modulation of cardiac recovery from ischemia/reperfusion injury. 122. BOTH ENDOGENOUS AND EXOGENOUS TESTOSTERONE DECREASE MYOCARDIAL STAT3 ACTIVATION AND SOCS3 EXPRESSION FOLLOWING ACUTE ISCHEMIA AND REPERFUSION. M. Wang, Y. Wang, J. Tan, J. Herrmann, A. Abarbanell, B. Weil, D. R. Meldrum; Indiana University School of Medicine, Indianapolis, IN Background: Signal transducer and activator of transduction 3 (STAT3) pathway has been shown to be cardioprotective. We also observed decreased STAT3/suppressor of cytokine signaling 3 (SOCS3) in male hearts, which was associated with worse post-ischemic myocardial function compared to females. However, it is unknown whether this down-regulation of myocardial STAT3/SOCS3 is due to testosterone in males. We hypothesized that following I/R: 1) endogenous testosterone decreases myocardial STAT3 activation and SOCS3 expression in male hearts; 2) administration of exogenous testosterone reduces myocardial STAT3/SOCS3 in female and castrated male hearts. Methods: To study this, Langendorff perfused rat hearts subjected to I/R injury were homogenized and assessed for phosphorylated-STAT3 (p-STAT3), totalSTAT3 (T-STAT3), SOCS3 and GAPDH by western blot. Groups: agematched adult males, females, castrated males (castr), males with flutamide (Flut) implantation (3-week release pellet), females and Castr males supplement with chronic (3-week) exogenous testosterone via 5alpha-dihydrotestosterone (DHT) release pellet implantation (n⫽ 5-8/group). Data were analyzed with student’s t-test, p⬍0.05⫽ statistically significant. Results: Castration or androgen receptor blockade (Flut) significantly increased SOCS3 expression (% of SOCS3/ GAPDH: Castr 98.8⫾16.1%, Flut 46.7⫾12.1% vs. 15.4⫾2.5%) in male hearts after I/R. However, only castration increased myocardial STAT3 activation (% of p-STAT3/T-STAT3: 92.2⫾24.3% vs. male 37.2⫾7.0%), but not flutamide treatment (39.9⫾11.3%). Notably, DHT replacement markedly decreased myocardial STAT3 activation and SOCS3 expression in castrated males (STAT3: DHT 42.1⫾10.1% vs. 79.9⫾13.8%; SOCS3: DHT 46.7⫾12.1% vs. 98.8⫾16.1%) and females (STAT3: DHT 39.3⫾5.5% vs. 65.9⫾7.7%; SOCS3: DHT 22.5⫾3.9% vs. 29.6⫾2.5%)) subjected to I/R. Conclusion: These results suggest that endogenous and exogenous testosterone decrease myocardial STAT3 activation and SOCS3 expression following I/R. This represents the initial demonstration of testosterone-downregulated STAT3/SOCS3 signaling in myocardium. 123. ACUTE POST-ISCHEMIC TREATMENT WITH ESTROGEN RECEPTOR-BETA AGONIST 2,3-BIS(4-HYDROXYPHENYL)-PROPIONITRILE IMPROVES MYOCARDIAL RECOVERY. N. Vornehm, M. Wang, A. Abarbanell, J. Herrmann, B. Weil, Y. Wang, D. Meldrum; Indiana University, Indianapolis, IN Background: Gender differences exist in cardiovascular disease. Female proestrus rats subjected to ischemia-reperfusion (I/R) injury developed less myocardial dysfunction than their male counterparts. Knocking out either estrogen receptor alpha or beta abolishes this effect; however, it remains unknown whether: 1) Post-ischemic treatment with the ER-␤ agonist, 2,3-bis(4-hydroxyphenyl)-propionitrile (DPN) induces cardioprotection following I/R injury, 2) Post-ischemic infusion of the ER-␣ agonist 4,4’,4”-(4-propyl-[H]-pyrazole-1,3,5triyl)trisphenol (PPT) does not induce protection following myocardial I/R injury. Methods: Isolated, perfused rat hearts (Langendorff) from adult males (n⫽4-6/group) were subjected to 25 minutes of ischemia followed by 40 minutes of reperfusion, during which time myocardial

contractile function was continuously monitored. During the entire 40 minutes of reperfusion, experimental hearts where infused with either ER-␣ agonist or ER-␤ agonist (1, 10, and 100 nM, respectively). Control hearts (n⫽7) where infused with a perfusate vehicle. Data were analyzed with two-way ANOVA, p⬍0.05⫽statistically significant. Results: Post-ischemic treatment with 10 and 100 nM of DPN significantly increased myocardial functional recovery following I-R exhibited as LVDP (60⫾9%-10nM, 52%⫾4-100nM vs. control 39%⫾5), ⫹dP/dt (67⫾10%-10nM, 56⫾2%-100nM vs. control 45⫾5%) and ⫺dP/dt (⫺65⫾9%-10nM, ⫺53⫾4%-100nM vs. control ⫺45⫾6%), with the maximum protection at 10nM. Groups treated with 10 and 100 nM DPN significantly improved myocardial function earlier during reperfusion (30 minute: 58⫾9%-10nM, 50⫾6%-100nM vs. control-27⫾3%). However, there was no significant functional recovery observed in PPT treated hearts following I-R. Conclusions: These results demonstrate that administration of ER-␤ agonist, DPN, decreases recovery time and attenuates myocardial dysfunction following I/R injury. Further clarification of these mechanisms may lead to therapeutic manipulation of estrogen receptors for clinical application in the treatment of myocardial I/R. 124. MITOCHONDRIAL RESPIRATORY COMPLEX I AND II ACTIVITIES ARE PRESERVED BY ISCHEMIC PRECONDITIONING. D. Lee, G. Steinbaugh, J. Zweier, J. A. Crestanello; The Ohio State University, Columbus, OH Mitochondrial respiratory complexes are damaged by ischemia reperfusion injury. While IPC preserves overall mitochondrial respiratory function after ischemia reperfusion, it is unclear which is the effect of IPC on individual mitochondria respiratory complexes. The purpose of this experiment was to determine the effect of IPC on mitochondrial respiratory complexes. Isolated rat hearts (n⫽6/ group) were subjected to either A) 40 minutes (min) of equilibration (EQ), 30 min of ischemia (I), and 30 min of reperfusion (RP) (CONTROL) or B) 10 min of EQ, three 5 min episodes of IPC, 30 min I, and 30 min of RP (IPC group). Interfibrillar (IF) and subsarcolemmal (SS) mitochondria were isolated at end reperfusion. Mitochondria complex I, II, and IV activities were assessed by polarography using specific substrates and inhibitors for each complex. Substrates for Complex I, II, and IV were glutamate and malate (4.7 mM), succinate (7 mM), tetramethyl-p-phenylenediamine (0.4 mM) respectively. Inhibitors for complex I, II, and III used were rotenone (188 nM), thenoyltrifluoroacetone (0.4 mM), and antimycin A (18.8 nM). Data is expressed as mean⫾SEM. Ischemia reperfusion impairs mitochondrial complex I, II and IV activity. IPC preserves both complex I and II activity in subsarcolemmal and interfibrillar mitochondria at end reperfusion. Complex IV activity is not affected by IPC. Selective protection of mitochondrial complex I and II during reperfusion is the mechanism responsible for preservation of respiration by IPC. Complex I

CONTROL IPC

Complex II

Complex IV

SS

IF

SS

IF

SS

IF

84 ⫾ 5 130 ⫾ 7*

55 ⫾ 4 99 ⫾ 12*

52 ⫾ 2 71 ⫾ 3*

24 ⫾ 2 35 ⫾ 3*

58 ⫾ 2 60 ⫾ 4

46 ⫾ 4 66 ⫾ 6

Data expressed in ng atoms O/mg protein. * p⬍0.05 vs CONTROL. 125. EUROSCORE FOR THE PATIENT UNDERGOING OFFPUMP CORONARY ARTERY BYPASS PREDICTS POSTOPERATIVE MORTALITY, CERTAIN MORBIDITIES, AND LENGTH OF STAY. H. Hirose, K. Tambara, H. Inaba, T. Yamamoto, M. Yamasaki, K. Kikuchi, A. Amano; Department of Cardiovascular Surgery, Juntendo University Hospital, Tokyo, Japan