Copyright @ 2006 by the Shock Society. Unauthorized reproduction of this article is prohibited. THE PARP-1 INHIBITOR INO-1001 FACILITATES HEMODYNAMIC STABILIZATION WITHOUT AFFECTING DNA REPAIR IN PORCINE THORACIC AORTIC CROSS-CLAMPINGYINDUCED ISCHEMIA/REPERFUSION Bala ´ zs Hauser,* ,$ Michael Gro ¨ ger,* Ulrich Ehrmann,* Maura Albicini,* ,¶ Uwe Bernd Bru ¨ ckner, ‡ Hubert Schelzig, † Balasubramanian Venkatesh, # Hongshan Li,** Csaba Szabo ´ ,** ,†† Gu ¨ nter Speit, § Peter Radermacher,* and Jochen Kick † *Sektion Ana ¨ sthesiologische Pathophysiologie und Verfahrensentwicklung, † Abteilung Thorax-und Gefa ¨ Qchirurgie, ‡ Sektion Chirurgische Forschung, and § Abteilung Humangenetik, Universita ¨ tsklinikum, Ulm, Germany; $ Aneszteziolo ´giai e ´ s Intenzı ´v Tera ´ pia ´ s Klinika, Semmelweis Egyetem, Budapest, Hungary; ¶ Istituto di Anestesiologia e Rianimazione dell’Universita ` degli Studi di Milano, Azienda Ospedaliera, Polo Universitario San Paolo, Milan, Italy; # Princess Alexandra and Wesley Hospitals, University of Queensland, Brisbane, Australia; **Inotek Pharmaceuticals Corporation, Beverly, Mass; and †† Klinikai Kı ´se ´ rleti Kutato ´-e ´ Huma ´n E ´ lettani Inte ´ zet, Semmelweis Egyetem, Budapest, Hungary Received 22 Nov 2005; first review completed 7 Dec 2005; accepted in final form 6 Jan 2006 ABSTRACT—Inhibition of poly (ADP-ribose) polymerase 1 (PARP-1) improved hemodynamics and organ function in various shock models induced by sepsis or ischemia/reperfusion. PARP-1, however, is also referred to play a pivotal role for the maintenance of genomic integrity. Therefore, we investigated the effect of the PARP-1 blocker INO-1001 on hemodynamics, kidney function, and DNA damage and repair during porcine thoracic aortic cross-clamping. The animals underwent 45 min of aortic cross-clamping after receiving vehicle (n = 9) or i.v. INO-1001 (n = 9; total dose, 4 mgIkg j1 , administered both before clamping and during reperfusion), data were recorded before clamping, before declamping, and 2 and 4 h after declamping. During reperfusion, continuous i.v. norepinephrine was incrementally adjusted to maintain blood pressure greater than or equal to 80% of the preclamping level. The plasma INO-1001 levels analyzed with high- pressure liquid chromatography were 1 to 1.4 2mol/L and 0.4 to 0.6 2mol/L before and after clamping, respectively. Although INO-1001Ytreated animals required less norepinephrine support, kidney function was comparable in the 2 groups. There was no intergroup difference either in the time course of DNA damage and repair (comet assay) as assessed both in vivo in whole blood before surgery, before clamping, before declamping, 2 h after declamping, and ex vivo in isolated lymphocytes (Ficoll gradient) sampled immediately before clamping and analyzed before, immediately, and 1 and 2 h after exposure to 4 bar 100% O 2 for 2 h. There was no difference either in the expression of the cyclin- dependent kinase inhibitor gene, p27, in the kidney (immunohistochemistry). The reduced norepinephrine requirements during reperfusion suggest a positive inotropic effect of INO-1001, as demonstrated by other authors. In our model, INO- 1001 proved to be safe with respect to DNA repair. KEYWORDS—Norepinephrine, renal function, DNA strand breaks, comet assay, cyclin-dependent kinase inhibitor gene, p27 INTRODUCTION Thoracic aortic cross-clamping is a typical example of ischemia/reperfusion (I/R) injury that affects those organs, which receive their blood supply from below the level of cross- clamping. I/R-induced O 2 radical formation causes oxidative DNA strand breakage, which, in turn, activates the nuclear enzyme poly (ADP-ribose) polymerase (PARP; (1, 2)). Activation of PARP results in an inefficient cellular metabolic cycle with transfer of the ADP-ribosyl moiety of NAD + to protein acceptors, which, in turn, results in depletion of cellular energy-rich phosphates and necrotic-type cell death. The major pathophysiological consequences of this cellular energy failure are vascular hyporeactivity, myocardial failure, and gut epithelial dysfunction (1, 2). Consequently, highly potent PARP inhibitors were developed (1, 2), which attenuated organ dysfunction in various large animal shock models (3Y10). In particular, these compounds improved heart function in sepsis (3), endotoxemia (4), or after I/R injury associated with cardiopulmonary bypass (8, 9). Given these encouraging results, we investigated the effect of the novel potent PARP-1 inhibitor INO-1001 (11) on hemodynamics and kidney function in a recently established porcine model of thoracic aortic cross-clampingYinduced I/R injury (12). Swine were investigated because of their striking similarity with humans with respect to both their susceptibility to oxidative stress and tissue antioxidant profiles (13, 14). 633 SHOCK, Vol. 25, No. 6, pp. 633Y640, 2006 Address reprint requests to Peter Radermacher, MD, Sektion Ana ¨sthesiologische Pathophysiologie und Verfahrensentwicklung, Universita ¨tsklinikum, D-89073 Ulm, Germany. E-mail: peter.radermacher@medizin.uni-ulm.de. B. Hauser and M. Gro ¨ger equally contributed to this work. This study was supported by the Deutsche Forschungsgemeinschaft (DFG Sche 899/2-1) and the Hungarian National Research Fund (OTKA; C.S.). Dr B. Hauser was the recipient of a Roman Herzog Research Fellowship of the Alexander von Humboldt Stiftung and the Gemeinnu ¨tzige Hertie Stiftung. INO-1001 was kindly provided by Dr Garry Southan (Inotek Pharmaceuticals Corporation, Beverly, MA). Prof B. Venkatesh was supported by a study leave from the Princess Alexandra and Wesley hospitals in Brisbane, Australia, to the University of Ulm in Germany. Special thanks are dedicated to Wolfgang Siegler, Tanja Schulz, Ingrid Eble, Christian Maier, Martin Mergenthaler, and Matthias Wuttke for their skillful technical assistance. DOI: 10.1097/01.shk.0000209561.61951.2e Copyright Ó 2006 by the Shock Society