Postconditioning and urocortin treatment conferredprotection against ischaemic–reperfusion injuryE. Roth, B. Cserepes, B. Racz, J. Lantos, S. Ferencz, M.Kurthy, Sz. Bertok, G. Jancso. Dept. of Surg Res and Techn,Univ. Pécs, Hungary

The aim of this study was to investigate the protective effectof urocortin and ischaemic postconditioning against ischaemicreperfusion injury on cultured cardiomyocytes. Isolated neonatalrat ventricular myocytes were divided into 4 groups. Cells wereexposed to 30 min ischaemia followed by ischaemic post-conditioning (group 1) or urocortin treatment for 10 min (group2) before the 2 h recovery period in normal cell culture medium.In ischaemic group (group 3) cells underwent only 30 minischaemia and 2 h recovery. In control group (group 4) cardiacmyocytes were incubated in normal cell culture medium. Fordetecting the cellular injury LDH release, trypan blue stainingand ratio of apoptosis/necrosis were examined. Our results show,that LDH content of culture medium, number of trypan bluestained dead cells and the rate of apoptotic and necrotized cellswas decreased in both ischaemic postconditioned and urocortintreated compared with ischaemic group. We can conclude thaturocortin induced such an efficient cell protective effect asischaemic postconditioning. Furthermore, urocortin might bealso used as a pharmacological postconditioning agent after aprolonged hypoxic stimulus against ischaemic cell injury.

Acknowledgments

Supported by OTKA T-048851; ETT 168/2006; OTKA T-060227 grants.

Keywords: Preconditioning; Cell culture; Myocytes

doi:10.1016/j.yjmcc.2007.03.559

Vardenafil limits infarction in isolated rat hearts atreperfusion via guanylyl cyclase in a small concentrationrangeThomas Krieg, Ole Maas, Ulrike Donat, Thomas Rütz, StephanFelix. University Greifswald, Germany

The type 5 phosphodiesterase inhibitor vardenafil (VAR)reduces myocardial infarct size following ischemia/reperfusioninjury when applied prior to ischemia in a model of in situ rabbithearts. Here, we investigated whether protection could also beafforded when VAR was applied at reperfusion in isolated rathearts. All hearts were subjected to 30min regional ischemia and120min reperfusion.While control hearts received no treatment,a second groupwas subjected to VAR during reperfusion starting5 min before the onset of reperfusion. VAR was used inconcentrations of 1, 10, 100, and 1000 nM. While 10 nM VARsignificantly reduced infarct size from 42.4±2.5% in the controlgroup to 26.2±2.7% (p=0.004 vs. control), lower and higherconcentrations failed to protect. The protection of 10 nM VARwas abolished with the co-administration of the guanylyl cyclase

inhibitor ODQ (10 μM, 47.0±3.5%). HL-1 cells were loadedwith TMRE (100 nM) which causes cells to fluoresce inproportion to their mitochondrial membrane potential (Ψm) andsubjected to the calcium ionophore calcimycin (cal, 100 μM).FACS analysis showed amarked reduction in mean fluorescenceafter 80 min compared to untreated cells (575±35 au. vs. 917±34 au., p<0.001). Pre-treatment of the cells with VAR (1 nM)preserved cell fluorescence (698±39 au., p=0.01 vs. cal), whichcould be blocked by the co-administration of ODQ. Takentogether, these results further support the hypothesis that PDE-5inhibitors induce protective effects in the ischemic heart inaddition to their well known clinical effects in the treatment oferectile dysfunction in men. VAR has a small effectiveconcentration range with unknown effects at high concentrationscausing a loss in protection.

Keywords: Postconditioning; PDE-5 inhibition

doi:10.1016/j.yjmcc.2007.03.560

Angiotensin II and postconditioning in reperfusion ofisolated rat heartM. Belal Aljabri, Britt N. Fuglesteg, Thomas V. Andreasen,Kirsti Ytrehus. Dept. of Medical Physiology, IMB, Univ. ofTromsø, Norway

Angiotensin II (angII) is a key to blood pressure regulation andinduces heart hypertrophy and failure. The present studyinvestigates how angII affects cell signalling and recovery offunction at reperfusion. Four groups of isolated perfused male rathearts were subjected to 30min ischemia plus 30min reperfusion.One group served as control, the otherswere treated at reperfusionwith: angII (0.1 μM), postconditioning by three 30 s cycles ofischemia–reperfusion (postc) or the combination (angII+postc).Left ventricular developed pressure (LVDP) and coronary flow(CF) were measured by an intraventricular balloon connected to apressure transducer and by timed collections of coronary effluate.At the end, hearts were freeze clamped for later WB analysisusing antibodies against p-Akt (ser473), Akt, p-GSK3β (ser9),GSK3β. The results (mean±S.E.M.) showed significant reduc-tion in recovery of LVDP in angII postc group (22.4±9.0%)whencompared to postc alone (60.7±7.8%), but not between angII(46.7±7.9%) and control (42.4±9.4%). Recovery of CF in angIIpostc group was significantly lower (57.6±11.9%) than controlgroup (72.7±7.8%) and to lesser extent lower than postc alone(64.2±13.9%). WB analysis showed reduced p-Akt and p-GSKin angII postc treated hearts compared to control. In conclusion,presence of angII seems to turn potential beneficial effects ofpostconditioning into detrimental effects. This could be due toreduced activity in cardioprotective cell signalling pathways.

Keywords: Angiotensin II; Reperfusion; Postconditioning

doi:10.1016/j.yjmcc.2007.03.561

S183ABSTRACTS / Journal of Molecular and Cellular Cardiology 42 (2007) S171–S189