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to the coronary perfusate during reperfusion, unlike VS-1, which resulted
cardioprotective when given before ischemia, but not in reperfusion. Actually, we
recently suggested that catestatin induces a sort of pharmacological postcondition-
ing (Penna et al. 2010a). We have reported that in an isolated and perfused heart
model, CST at a concentration of 75 nM is able to reduce I/R injuries when given
during the early reperfusion. The CST concentration we used in the isolated rat heart
is within the same range of concentrations of the precursor CgA detected in plasma
of patients suffering IMA (about 1 nM) or cardiac heart failure (about 10 nM)
(O’Connor et al. 2002 ; Wang et al. 2011 ). It is also similar to the peptide concentra-
tion (IC50 ~ 100 nM) which depresses myocardial force of contraction in normal
hearts (O’Connor et al. 2002 ; Wang et al. 2011 ), and seems slightly lower than the
IC50 value for the inhibition of the nicotinic cholinergic receptor-mediated catechol-
amine release in bovine adrenal chromaffin cells induced by CST (Mahata et al.
1997 ; Mahata 2004 ). In the isolated rat heart model, CST not only reduces infarct
size, but also limits post-ischemic contracture and improves post-ischemic systolic
function. Moreover, we reported that CST is protective in a model of isolated cardio-
myocytes (Penna et al. 2010a). In this model CST increases viability rate of cells
exposed to simulated ischemia. This direct protective effect on cardiomyocytes may
explain why CST applied in the reperfusion is protective especially in terms of
improvement of post-ischemic cardiac function. Since protection was observed in
both isolated heart and isolated cardiomyocytes, we suggested that the protective
effect is primarily due to a direct effect on the myocardium and does not necessarily
depend on the antiadrenergic and/or endothelial effects of CST (Penna et al. 2010a).
However, endothelial effects could be additive. In fact, Alloatti and coworkers
(Bassino et al. 2015 ) have shown that catestatin may also act on endothelial cells.
About the mechanisms of action of CST, we have shown that CST given in early
reperfusion facilitates the phosphorylation of Akt, PKCε and GSK3β which may
regulate mitochondrial function (Bassino et al. 2015 ; Penna et al. 2014 ; Perrelli et al.
2013 ). The mechanisms seem similar to those described in ischemic PostC. However,
the protective pathways partially diverge, as mitoKAT P channel blockade, by
5-hydroxydecanoate, 5-HD, or ROS scavenger does not avoid CST- dependent con-
tracture limitation, whereas PKC inhibition abolishes infarct size, antiapoptotic
activity, contracture limitation and systolic function recovery. Since 5-HD attenuates
the PKCε activation due to CST, a reverberant circuit (PKCε- dependent/mitoKAT P
channel activation/ROS formation/PKCε re-activation, Fig. 3 ) has been hypothesized
(Perrelli et al. 2013 ). We also observed that the anti-infarct effect of CST is abolished
by scavenging ROS with a sulfhydryl donor specific for mitochondrial activity
(Perrelli et al. 2013 ), namely N-(2-mercaptopropionyl) glycine (MPG, 300 μM);
whereas the contracture limitation is not affected by MPG. Recently these results
have been confirmed in isolated cardiac cells, in fact in this in vitro model, catestatin
exerts a direct action on cardiomyocytes with activation of PI3K/NO/cGMP pathway
as trigger and mitochondrial membrane potential preservation as the end point of its
action (Bassino et al. 2015 ; Perrelli et al. 2013 ). The protection is confirmed in H9c2
C. Penna and P. Pagliaro