Fig. 1.

Experimental protocol. Twenty groups of mice were used. On day 2, mice in groups I–IV underwent a 30-min coronary occlusion followed by 24 h of reperfusion. On day 1, mice in group II (n = 9, late PC group) and group IV (n = 9, IL-6^−/− late PC group) underwent a sequence of six 4-min coronary occlusion (O)/4-min reperfusion (R) cycles, while mice in group I (n = 17, control group) and group III (n = 9, IL-6^−/− control group) did not undergo any intervention. Mice in group V (n = 6) underwent 1 h of open-chest state (n = 3) or six cycles of 4-min coronary occlusion/4-min reperfusion (n = 3), and the hearts were harvested 30 min later for IL-6 immunolocalization. In groups VI–VIII (n = 6 in each group), wild-type mice underwent no intervention (group VI), 1 h of open-chest state (group VII), or six cycles of 4-min coronary occlusion/4-min reperfusion (group VIII), and myocardial tissue samples were harvested 2 h later for the measurement of myocardial IL-6 levels by ELISA. In groups IX–XX (n = 6 in each group), wild-type (groups IX, X, XIII, XIV, XVII, and XVIII) and IL-6^−/− (groups XII, XV, XVI, XIX, and XX) mice underwent six cycles of 4-min coronary occlusion/4-min reperfusion (groups X, XII, XIV, XVI, XVIII, and XX) or 1-h open-chest state (groups IX, XIII, XV, XVII, and XIX), and myocardial tissue samples were harvested 5 min [groups IX–XII (JAK activity assays)], 30 min [groups XIII–XVI (STAT activation assays)] and 24 h [groups XVII–XX (iNOS and COX-2 levels)] later for biochemical assays.