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already damaged by the ischemia, thus favoring the cell death and in particular the
contraction band-necrosis and apoptosis (Ambrosio et al. 1991 , 1993 ; Gottlieb et al.
2009 ; Hoffman et al. 2004 ; Pagliaro et al. 2011 ; Tritto and Ambrosio 2001 ; Zhao
2004 ; Zhao and Vinten-Johansen 2002 ). Superoxide anion may react with NO pos-
sibly present, forming peroxynitrite (ONOO−). Actually, the scarcity of NO is cor-
related to the production of ONOO− (Beauchamp et al. 1999 ; Kaeffer et al. 1997 )
that takes part with O 2 − to the myocardial injury (Ferdinandy and Schulz 2003 ;
Lefer and Lefer 1991 ; Ronson et al. 1999 ). The preserved production of NO may be
also protective via peroxynitrite reduction, in the so-called secondary reaction,
which is due to the reaction of ONOO− with NO and which in turn will lead to pro-
tein S-nitrosylation (SNO of proteins) (Penna et al. 2011a). This S-nitrosylation of
proteins is a phenomenon involved in the cardiac effects induced by Catestatin,
including modulation of cardiac force of contraction and cardioprotection in normo-
tensive and hypertensive rat hearts (Angelone et al. 2015 , 2012 ; Penna et al. 2011b;
Perrelli et al. 2013 ) (see below). On the other hand, the dismutation of O 2 − in hydro-
gen peroxide (H 2 O 2 ) mediated by superoxide-dismutase can also reduce signifi-
cantly the injury; yet in the presence of Fe2+ or Cu2+, H 2 O 2 is transformed in hydroxyl
anion (OH-.), thus resulting in more toxic effects than O 2 − and H 2 O 2. This brief
description of ROS/RNS production/formation during I/R may lead to the miscon-
ception that radicals are prevalently deleterious and some radical species are good
and other are bad. This is not always the case, as we can see in the following descrip-
tion of cardioprotective pathways, some reactive species, including OH-. may exert
protective effects, depending on several factors, including compartmentalization
and flux velocity of reactions.
Nevertheless, the oxidative stress in the context of I/R may result in acute inflamma-
tory response with activation of vascular endothelial cells and leukocytes and with the
expression on cell surface of adhesion molecules, leading to leukocyte/capillary plug-
ging, release of cytokines, and pro-inflammatory agents which determine the onset and
maintenance of post-ischemic inflammation (Zhao and Vinten- Johansen 2002 ).
Other deleterious factor of reperfusion injury is the cellular Ca2+overload; this
phenomenon starts during ischemia, for depletion of ATP and consequent inhibition
of ionic pump, and it may be further increased during reperfusion. During I/R, the
altered cytosolic Ca2+ handling may induce structural fragility and excessive con-
tractile activation, with a band-necrosis and progressive increase of diastolic con-
tracture (Hoffman et al. 2004 ; Piper et al. 2003 ; Siegmund et al. 1993 ). The overload
of Ca2+ contributes to the augmentation of cellular osmolarity, which will be respon-
sible of explosive swelling and necrosis of cardiomyocytes. Also, the mitochondria
undergo rapid changes in matrix Ca2+ concentration; in fact, while cytosolic Ca2+
overload is responsible of expression/release of proapoptotic elements, Ca2+ over-
load within mitochondria leads to the release of pro-apoptotic cofactors, and to the
opening of mitochondrial transition pore (mPTP) (Zhao 2004 ).
Actually, mPTP are kept closed during the ischemia by the acidic environment.
During reperfusion, the pore formation is favored by several factors, including the pH
recovery, the oxidative stress, the ATP depletion and, as said, the high levels of intra-
mitochondrial Ca2+ concentration (Gateau-Roesch et al. 2006 ). The opening of mPTP,
C. Penna and P. Pagliaro