Comparative effects of ischemic pre and postconditioning on ischemia-reperfusion injury in spontaneously hypertensive rats (SHR)

Abstract

Brief episodes of myocardial ischemia-reperfusion applied early in reperfusion may attenuate the reperfusion injury, strategy called ischemic postconditioning (IPO). Our objective was to examine the effects of IPO compared with ischemic preconditioning (IP) on postischemic myocardial dysfunction in spontaneously hypertensive rats (SHR). Isolated hearts from SHR and normotensive WKY rats were subjected to the following protocols: (1) Ischemic control (IC): global ischemia 20 min (GI20) and reperfusion 30 min (R). (2) IPO: three cycles of R30sec-IG30sec at the onset of R; (3) IP: a cycle of IG5-R10 previous to GI20, (4) IPO in the presence of chelerythrine, an inhibitor of protein kinase C (PKC). Systolic and diastolic function were assessed through developed pressure (LVDP) and end diastolic pressure (LVEDP), respectively. Lipid peroxidation was estimated by thiobarbituric reactive substance (TBARS) concentration. IPO significantly improved postischemic dysfunction. At the end of R, LVDP recovered to 87 +/- 7% in WKY and 94 +/- 7% in SHR vs. 55 +/- 11% and 58 +/- 12% in IC hearts. LVEDP reached values of 24 +/- 6 mmHg for WKY and 24 +/- 3 mmHg for SHR vs. 40 +/- 8 and 42 +/- 5 mmHg in IC hearts. Similar protection was achieved by IP. TBARS contents of SHR hearts were significantly diminished by IP and IPO. PKC inhibition aborted the protection of myocardial function and attenuated the diminution of lipid peroxidation conferred by IPO. These data show that IPO was as effective as IP in improving the postischemic dysfunction of hearts from SHR hearts, and that this cardioprotection appears to be associated with a diminution of ROS-induced damage involving the PKC activation.

Postconditioning the Heart: Analysis of Experimental and Clinical Data

“…В 2007 г. итальянские физиологии опубликовали ре-зультаты своих экспериментов на изолированных сердцах обычных крыс (линия Wistar) и органах животных со спонтанной гипертензией (линия SHR, Spontaneously Hypertensive Rats) [12]. Сердца подвергали глобальной ишемии (20 мин) и реперфузии (30 мин).…”

“…В реперфузи-онном периоде определяли давление, развиваемое левым желудочком (ДРЛЖ), и конечное диастолическое дав-ление (КДД). Посткондиционирование способствовало быстрому восстановлению ДРЛЖ и снижало КДД в обеих экспериментальных группах животных [12].…”

Adaptive Phenomenon of Ischemic Postconditioning of the Heart. Perspectives of Clinical Use

“…В 2007 г. аргентинские физиологи опубликовали ре-зультаты своих экспериментов на изолированных перфу-зируемых сердцах крыс линий Wistar и SHR (spontaneously hypertensive rats) [35]. Сердца подвергали воздействию глобальной ишемии (20 мин) и реперфузии (30 мин).…”

“…Посткондиционирование обеспечивали с помощью 3 ци-клов реперфузии (30 с) и ишемии (30 с). Авторами было установлено, что посткондиционирование улучшает вос-становление насосной функции сердца в реперфузи-онном периоде как в экспериментах на изолированных сердцах крыс линии Wistar, так и в опытах на сердцах животных линии SHR [35].…”

Lipid Peroxidation and Reperfusion Injury in Hypertrophied Hearts

“…Although there are some studies showing the beneficial effects of IP in hypertensive animals [12][13][14][15], under certain circumstances the effectiveness of that intervention is questioned [16][17][18]. A recent investigation performed in our laboratory shows that a single cycle of IP attenuated the myocardial stunning produced by 20-min global ischemia in SHR [19] and decreased the lipid peroxidation. Whether this protective action of IP is operating at more extended ischemic period and involves changes in oxidative stress in this rats strain is a point that needs to be clarified.…”