Effect of hydromorphone postconditioning on myocardial ischemia-reperfusion injury in isolated rat hearts and the role of mitochondrial permeability transition pore

Abstract

Objective To investigate the effect of hydromorphone postconditioning on ischemia-reperfusion(I/R)injury in isolated rat hearts and the role of mitochondial permeability transition pore(mPTP). Methods Male Sprague-Dawley rats, aged 2–3 months, weighing 250–320 g, were used in the study.The rats were heparinized and anesthetized with intraperitoneal 10% chloral hydrate 350 mg/kg.The hearts were excised, and perfused in a Langendorff apparatus with K-H solution saturated with 95% O2-5% CO2 at 36.5–37.5 ℃.Forty isolated rat hearts were randomly divided into 4 groups(n=10 each)using a random number table: control group(group C), group I/R, hydromorphone postconditioning group(group H), and hydromorphone postconditioning + mPTP opener lonidamine group(group HL). Group C was continuously perfused with K-H solution for 120 min.Group I/R was perfused with K-H solution for 30 min, the perfusion was then suspended for 30 min, and group I/R was perfused with K-H solution for another 30 min.Group H was perfused with K-H solution for 30 min, the perfusion was then suspended for 30 min, and group H was perfused with K-H solution containing 0.3 μmol/L hydromorphone for 10 min, and then with K-H solution for 50 min.Group HL was perfused with K-H solution for 30 min, the perfusion was then suspended for 30 min, and group HL was perfused with K-H solution containing 0.3 μmol/L hydromorphone and 30 μmol/L lonidamine for 10 min, and then with K-H solution for 50 min.At 30 min of equilibration(T0), and 30 and 60 min of reperfusion(T2, 3), left ventricular systolic pressure(LVSP), left ventricular end-diastolic pressure(LVEDP), left ventricular developed pressure(LVDP), ±dp/dtmax, heart rate(HR), and coronary flow(CF)were measured.The concentrations of lactic dehydrogenase(LDH), creatine kinase-MB(CK-MB), and troponin-T(Tn-T)in the coronary effluent were determined at T0 and T3.The coronary effluent was collected at T0 and 15 min of reperfusion(T1), nicotinamide-adenine dinucleotide(NAD+ )concentrations were measured using enzyme-linked immunosorbent assay to reflect the degree of mPTP opening.The myocardial infarct size was determined at T3 by TTC staining. Results Compared with group C, LVDP, HR, ±dp/dtmax and CF were significantly decreased, and LVEDP was increased at T2, 3, and the concentrations of LDH, CK-MB and Tn-T in the coronary effluent, myocardial infarct size at T3, and NAD+ concentrations in the coronary effluent at T1 were increased in group I/R(P<0.05). Compared with I/R and HL groups, LVDP, ±dp/dtmax, CF and HR were significantly increased, and LVEDP was decreased at T2, 3, and the concentrations of LDH, CK-MB and Tn-T in the coronary effluent, myocardial infarct size at T3, and NAD+ concentrations in the coronary effluent at T1 were decreased in group H(P<0.05). Conclusion Hydromorphone postconditioning can reduce myocardial I/R injury in isolated rat hearts, and the mechanism is related to inhibition of mPTP opening. Key words: Hydromorphone; Myocardial reperfusion injury; Mitochondrial membrane transport proteins; Postconditioning