The removal of Ca2+ from the cardioplegic solutions could cause the danger of inducing a "calcium paradox" during reperfusion. Since intracellular Ca2+ activities are coupled to Na+ activities via Na(+)-Ca2+ exchange, an increase in intracellular Na+ activities during the cardioplegia could cause an abrupt Ca2+ influx when reperfused. To study the effects of Na+ and Ca2+ concentrations in cardioplegic solutions on intracellular Ca2+ activities during the cardioplegia and subsequent recovery period, the membrane potential and intracellular Na+ and Ca2+ activities of guinea pig ventricular papillary were measured. 1) A cardioplegia with low Ca2+ cardioplegic solution significantly decreased the overshoot and duration of the first action potential after cardioplegia, but the changes in action potential configuration were minimized after a cardioplegia with Ca2+ concentration adjusted according to the Na(+)-Ca2+ exchange mechanism. 2) Intracellular Na+ activity was continuously decreased during the cardioplegia, and the intracellular Na+ activity 20 minutes after cardioplegia was the highest with low Ca2+ cardioplegic solution. 3) Intracellular Na+ and Ca2+ activities were continuously decreased during the cardioplegia with Ca2+ concentration adjusted according to the Na(+)-Ca2+ exchange mechanism. 4) During a reperfusion of Tyrode solution after cardioplegia intracellular Na+ and Ca2+ activities were increased. Intracellular Ca2+ activity was increased more rapidly than intracellular Na+ activity. 5) The rate of increase in intracellular Ca2+ activity with reperfusion of Tyrode solution was dependent upon intracellular Na+ activity during cardioplegia, in such a way that the higher the intracellular Na+ activity was, the faster the intracellular Ca2+ activity increased. These data suggest that Na(+)-Ca2+ exchange mechanism may play an important role in the regulation of intracellular Ca2+ activity during recovery after cardioplegia.
Animal ; Calcium/*pharmacology ; Cardioplegic Solutions/*pharmacology ; Ions ; *Myocardial Reperfusion ; Osmolar Concentration ; Papillary Muscles/cytology/*drug effects ; Sodium/*pharmacology ; Solutions/pharmacology

This study was undertaken to explore the myocardioprotective effects of the combination of ischemic preconditioning (IP) with hypothermia and St.II Thomas crystalloid cardioplegic solution (CCS) on immature hearts in the rabbit. Isolated immature rabbit hearts were perfused with Krebs-Henseleit bicarbonate buffer on Langendorff apparatus. In experiment 1, 24 hearts were divided into 4 groups (n=6 in each group): Con, IP1, IP2 and IP3 group. Hearts of the four groups underwent 0, 1, 2 or 3 cycles of IP respectively. Then all the hearts were subjected to a sustained ischemia period of 2 h at 20 degrees C and a postischemic reperfusion period of 30 min at 37 degrees C. In experiment 2, 48 hearts were divided into 6 groups (n=8 in each group): SCon1, SIP1, SCon2, SIP2, SCon3 and SIP3 group, according to hypothermia and the duration of sustained ischemia (30 min at 32 degrees C; 90 min at 25 degrees C, 2 h at 20 degrees C). The SIP1, SIP2 and SIP3 groups were preconditioned twice before the sustained hypothermic ischemia, while the SCon1, SCon2 and SCon3 groups were not preconditioned. CCS was applied during sustained ischemia, all the hearts were reperfused for 30 min at 37 degrees C. Heart rate (HR), left ventricular developed pressure (LVDP) and peak rate of increase or decrease of left ventricular pressure (+/-dp/dt(max)) were recorded. Tissue concentration of adenosine triphosphate (ATP), malondialdehyde (MDA) and the activity of superoxide dismutase (SOD) were measured. At the end of reperfusion, values of product of LVDP and HR, +/-dp/dt(max) in IP2 group were 96%+/-21%, 101%+/-19% and 84% +/-15% of the baseline values respectively, which were significantly higher than those of Con group and IP3 group (P<0.01, P<0.05); also, the ATP content of IP2 group was higher than that of the Con group (P<0.01). When CCS was applied during sustained period of hypothermic ischemia at 32 degrees C or 25 degrees C, recovery rates of RPP (rate product, =LVDPxHR) and +dp/dt(max) in SIP1 group were 87% +/-14% or 99% +/-26% of the baseline values respectively (P<0.05, vs SCon1 group), the values in SIP2 group changed to 87% +/-16% or 102% +/-20% respectively (P<0.05, vs SCon2 group). Contents of ATP in SIP1 and SIP2 groups were significantly higher than those of SCon1 or SCon2 groups respectively (P<0.05), but MDA content of the two groups were significantly lower than those of SCon1 or SCon2 groups (P<0.05) respectively. The study indicates that IP attenuates hypothermic ischemia/reperfusion injury to immature rabbit hearts under 20 degrees C ischemia, two cycles of IP showing better myocardioprotective effects than 1 or 3 cycles of IP. When IP was combined with CCS which were applied during hypothermic ischemia period, the beneficial effects of IP were weakened as the temperature during the hypothermic period was elevated.
Animals ; Animals, Newborn ; Cardioplegic Solutions ; pharmacology ; Female ; Hypothermia, Induced ; In Vitro Techniques ; Ischemic Preconditioning, Myocardial ; methods ; Isotonic Solutions ; pharmacology ; Male ; Myocardial Reperfusion Injury ; prevention & control ; Rabbits

OBJECTIVETo investigate whether the mitochondrial ATP-sensitive potassium channel (mitoK(ATP)) opener diazoxide as an additive to cardioplegia solution could enhance myocardial protection during hypothermic preservation of the rat heart.

METHODSThe Langendorff model of isolated rat heart was used. After equilibrium, the hearts were stored in Celsior cardioplegia solution at 4 degree with or without supplement of diazoxide for 3 or 8 h followed by 60 minutes reperfusion. The recovery of cardiac contractile function, myocardial enzyme leakage in the coronary effluent, and myocardial water content were determined. The myocardial ultrastructure was also observed.

RESULT(1) Treatment of diazoxide improved the recovery of left ventricular developed pressure and decreased the leakage of myocardial enzymes, lactate dehydrogenase (LDH) and creatine kinase (CK), at the 2nd and 4th minute of reperfusion of rat heart after hypothermic preservation for 3 h. (2) After hypothermic preservation for 8 h, diazoxide improved the recovery of left ventricular developed pressure and decreased the leakage of myocardial enzymes (LDH, CK and glutamic oxalic transaminase) during reperfusion. Moreover, left ventricular end-diastolic pressure was significantly lower in diazoxide-treated hearts than that of hearts in Celsior solution. (3) Diazoxide significantly decreased the water content of myocardium and increased coronary flow of the hearts compared with those in control after hypothermic preservation for 8 h. (4) Impairment of myocardial ultrastructure after 8 h hypothermic preservation was alleviated in hearts treated with 30 mol/L diazoxide. (5) The cardiac effects of 30 mol/L diazoxide were attenuated by a mitoK(ATP) blocker 5-hydroxydecanoate (100 micromol/L).

CONCLUSIONDiazoxide as a supplementation in cardioplegia solution could enhance myocardial protection during hypothermic heart preservation via opening of mitochondrial K(ATP) channel.

Animals ; Cardioplegic Solutions ; Cryopreservation ; Diazoxide ; pharmacology ; Heart ; Male ; Organ Preservation ; Organ Preservation Solutions ; pharmacology ; Potassium Channels ; drug effects ; Rats ; Rats, Sprague-Dawley

OBJECTIVETo observe the myocardial protection of cardioplegic solution with Salvia miltiorrhizae (SM) in extracorporeal circulation of coronary artery bypass graft (CABG) and to investigate the mechanisms of SM.

METHODS30 patients who received CABG under extracorporeal circulation were randomly assigned to two groups, the observation group (15 cases) and the control group (15 cases). Patients in the observation group received the cardioplegic solution with SM and those in the control group received the cardioplegic solution without SM. The indices such as serum SOD activities, MDA contents, LDH, CK-MB, cTnl levels, the rate of heart reskip, activated coagulation time (ACT), the time of assisted respiration, and the days of in-hospital after operation were observed in the two groups pre-operation, post-operation, 6 h and 24 h post-operation, respectively.

RESULTSWhen compared with the control group, MDA contents, LDH, CK-MB, cTnl levels were lower, SOD activities (all P<0.05) and heart re-skip rate (P>0.05) higher in the observation group. There was no statistical significance in the time of assisted respiration, the days of in-hospital, or ACT in the two groups (P>0.05).

CONCLUSIONSThe application of cardioplegic solution with SM in extracorporeal circulation of CABG showed obvious myocardial protection. It had better effects than the cardioplegic solution with no SM.

Aged ; Cardioplegic Solutions ; pharmacology ; therapeutic use ; Coronary Artery Bypass ; Drugs, Chinese Herbal ; pharmacology ; therapeutic use ; Extracorporeal Circulation ; methods ; Female ; Humans ; Male ; Middle Aged ; Myocardium ; metabolism ; Salvia miltiorrhiza

OBJECTIVETo explore the appropriate temperature of the kalium-verapamil-propranolol (KVP) cardioplegia by observation of the effect on the function of the immature rat heart.

METHODSIsolated hearts from immature rats were perfused by Langendorff method, and assigned to 1 of the following 5 groups (n = 6-8): control, continuously perfused for 170 min at 36 degrees C, normal temperature, normal perfused for 20 min, changed to perfuse with KVP for 3 min then no perfusion 87 min (ischemia 90 min), followed by 60 min reperfusion. 3 groups of low temperature, perfused for 15 min, cool down to 32 degrees C, 28 degrees C and 24 degrees C especially in 5 min, and at 20th min. heart rate (b/min), tension (g), contraction force (g), peak systolic velocity (dT/dt(max)), peak diastole velocity (dT/dt(max)), coronary flow (Drop/min) were monitored during the whole perfusion.

RESULTSCompared to control group, the heart tension increased after 50 min KVP ischemia. The protection of KVP in normal temperature (36 degrees C) was better than lower temperature (32 degrees C, 28 degrees C, 24 degrees C) such as reducing bad contraction, keeping normal myocardium tension,recovering heart rate, recovering the fuction of contraction force and protecting the coronary flow.

CONCLUSIONThe KVP cardioplegia in normal temperature has the better effect than that in hypothermia to protect the immature heart.

Animals ; Cardioplegic Solutions ; pharmacology ; Heart ; physiopathology ; Heart Arrest, Induced ; In Vitro Techniques ; Male ; Myocardial Reperfusion Injury ; prevention & control ; Rats ; Rats, Sprague-Dawley ; Temperature ; Ventricular Dysfunction ; prevention & control

OBJECTIVETo study the protective effect of cold autologous blood cardioplegic solution on the heart of infants with cyanotic congenital heart disease (CCHD).

METHODSNinety-six infants with CCHD who underwent cardiopulmonary bypass (CPB) were randomly and equally divided into three groups: histidine-tryptophan-ketoglutarate (HTK) solution, cold non-autologous blood cardioplegic solution, and cold autologous blood cardioplegic solution. The right auricular tissues were taken before aortic cross-clamping and at 30 minutes after aortic declamping, and ATP level and energy charge (EC) in the myocardium were measured. Venous blood was collected before and immediately after CPB, and the serum levels of creatine kinase (CK)-MB and cardiac troponin I (cTnI) were measured. The clinical parameters, such as the re-beat time and re-beat rate during CPB, cardiac index, dependence on positive inotropic agents, and left ventricular ejection fraction (LVEF) at 2 hours after CPB, the incidence rate of arrhythmia within 24 hours after CPB, and postoperative complications and mortality, were recorded.

RESULTSAt 30 minutes after aortic declamping, the three groups showed significantly decreased ATP and EC levels (P<0.05), and the cold autologous blood group had significantly higher ATP and EC levels than the other two groups (P<0.05). Immediately after CPB, the three groups showed significantly increased serum levels of CK-MB and cTnI (P<0.05), and the cold autologous blood group had significantly lower serum levels of CK-MB and cTnI than the other two groups (P<0.05). The cold autologous blood group had significantly better outcomes than the other two groups in terms of the re-beat time during CPB and the dependence on positive inotropic agents and LVEF at 2 hours after CPB (P<0.05).

CONCLUSIONSCold autologous blood cardioplegic solution is superior to HTK and cold non-autologous blood cardioplegic solutions in preserving myocardial energy and reducing myocardial injury in infants with CCHD who undergo CPB, thus providing a better protective effect on the heart.

Cardioplegic Solutions ; pharmacology ; Cardiopulmonary Bypass ; Energy Metabolism ; Female ; Glucose ; pharmacology ; Heart Defects, Congenital ; metabolism ; surgery ; Humans ; Infant ; Infant, Newborn ; Male ; Mannitol ; pharmacology ; Myocardium ; metabolism ; Potassium Chloride ; pharmacology ; Procaine ; pharmacology ; Ventricular Function, Left

AIMTo investigate the effects of polarizing cardioplegia solution with sodium channel inhibitor tetrodotoxin (TTX) on intracellular free Na+ concentration ([Na+]i) in isolated cardiomyocytes of rat.

METHODSVentricular myocytes with beating were isolated from adult rat hearts by enzymatic dissociation, randomly created in group base, group STH2 (contrast group of ischemia/reperfusion) and group TFX (treated group). Both Group STH2 and group TTX were arrested by St. Thomas No. 2 cardioplegia solution and TTX cardioplegia solution respectively, the arrest/re-beating cell model imitating MIRI being established, and imaged by laser scanning confocal microscopy (LSCM) for measuring [Na+]i of cardiomyocytes in different period. The morphology of cardiomyocytes was observed under the inverted microscope.

RESULTS[Na+]i of cardiomyocytes in both group TTX and group STH2 after re-beating was higher than that in group base (P < 0.01), and [Na+]i in group TTX was lower than that in group STH2 (P < 0.01). During arrest, the elevation of [Na+]i in group TTX was lower than that in group STH2. During arrest, the elevation of [Na+]i in group TTX was lower than that in group STH2. Morphologically, after re-beating, the ratio of active cardiomyocytes with normal form in group TTX was higher than that in group STH2 (P < 0.01).

CONCLUSIONContrast depolarized cardioplegia solution, TTX cardioplegia solution could alleviate ischemia reperfusion injury and intracellular Na+ overload of cardiomyocytes.

Animals ; Cardioplegic Solutions ; pharmacology ; Cell Hypoxia ; Cells, Cultured ; Female ; Heart Arrest, Induced ; Male ; Myocardial Reperfusion Injury ; prevention & control ; Myocytes, Cardiac ; cytology ; metabolism ; Rats ; Sodium ; metabolism ; Sodium Channel Blockers ; pharmacology ; Tetrodotoxin ; pharmacology

AIMTo explore the appropriate dose of the verapamil and propranolol in kalium cardiaplegia (KVP) by observation of the effect on the function of ischemic immature rat heart and compared with ST. Thomas II cardiaplegia.

METHODS48 isolated hearts from Sprague-Dawley rats of 60 to approximately 80 g body weight, 22 +/- 2 days, male or female are perfused by Langendorff method for 20 min, and assigned to 1 of the following 6 groups (n = 8): control (CON), continuously perfused for 150 min. Ischemia/reperfusion (I/R), perfused with Locke's solution without glucose and oxygen equilibration for 3 min then no perfusion 27 min, repeated 3 cycles (ischemia for 90 min), followed by reperfusion for 60 min. Ischemia protected with ST. Thomas II cardioplegia (ST), each 3 min perfusion with ST. Thomas II cardioplegia during ischemia. Ischemia protected with three dose KVP cardioplegia (L, M, and H), perfused with ST. Thomas II cardioplegia containing verapamil and propranolol (x 10(-7) mol L(-1)) respectively 2.0, 0.34 (L), 6.8, 1.1 (M), 20,3.4 (H) during each 3 min perfusion of ischemia. Heart rate (min (-1), tens on(g), contraction force(g), peak systolic velocity (g.s-1), peak diastole velocity (g.s-), coronary flow (ml x min(-1 ), re-beat time (s) were monitored during the ischemia/ reperfusion.

RESULTSCompared to CON group, heart tension was rose when ischemia for 40 min and kept higher and could not rebeat after reperfusion in I/R group, In ST group, heart tension was rose after ischemia for 60 min and could re-beat but the pulse was weaker. Compared with ST group, KVP decreased the ischemic cardiac tension in dose dependently and the re-beat was stronger in L, M, and H groups. While compared with CON group, in L group, heart tension was rose when ischemia for 60 min and the re-beat was weaker. In H group, the heart tension was maintained lower when ischemia for 40 min and the re-beat was delay and weaker. Only in M group, heart tension was maintained stable during ischemia for 90 min and re-beat was stronger after reperfusion.

CONCLUSIONKalium cardiaplegia containing verapamil 6.8 x 10(-7) mol x L(-1) and propranolol 1.1 x 10(-7) mol x L(-1) has the best effect to protect the immature heart from ischemic injury.

Animals ; Cardioplegic Solutions ; administration & dosage ; pharmacology ; Female ; Heart ; drug effects ; In Vitro Techniques ; Male ; Myocardium ; metabolism ; Propranolol ; administration & dosage ; pharmacology ; Rats ; Rats, Sprague-Dawley ; Reperfusion Injury ; prevention & control ; Verapamil ; administration & dosage ; pharmacology

To study the effects of different pH HEPES-KH reperfusate solution on immature myocardial protection, isolated perfused Langendorff model from immature rabbit hearts were developed formed. Control group (C) was perfused only with pH 7.4 HEPES-KH solution for 90 min. Ischemia/reperfusion group (group I/R) was perfused with pH 7.4 HEPES-KH solution before ischemia or after ischemia. Experimental group (group E), after ischemia, was perfused with pH 6.8, pH 7.1 and pH 7.4 HEPES-KH solutions for 5 min, 5 min, and 20 min, respectively. The left ventricular function recovery, MWC, LDH and CK leakage, MDA, ATP content, and SOD activity were determined. Our results showed that the left ventricular function recovery, ATP content and SOD activity in group E were higher than those of group I/R (P < 0.05). MWC, MDA content, LDH and CK leakage in group E were lower than those of group I/R (P < 0.05). These findings suggested that pH paradox might be one of important mechanisms for immature myocardial ischemia-reperfusion injury, and acidic perfusate, at the beginning of reperfusion, might attenuate pH paradox and ameliorate functional recovery in isolated perfused immature rabbit hearts.
Animals ; Cardioplegic Solutions ; pharmacology ; Female ; Heart ; physiopathology ; Heart Arrest, Induced ; Hydrogen-Ion Concentration ; Male ; Myocardial Ischemia ; metabolism ; physiopathology ; Myocardial Reperfusion Injury ; metabolism ; physiopathology ; prevention & control ; Myocardium ; metabolism ; Rabbits ; Random Allocation ; Superoxide Dismutase ; metabolism

Whether the ATP-sensitive potassium channel opener pinacidil can provide myocardial protective effects in prolonged isolated global ischemic rat heart was investigated. On modified isolated rat working heart model, 40 hearts were divided into four groups randomly: Hyperpolarized arrest H-K solution containing pinacidil (50 mumol/L) (P1 and P2) and depolarized arrest St. Thomas' solution (S1 and S2) subjected to 15 degrees C hypothermia, 60 min (P1 and S1) or 120 min (P1 and S2) of ischemia and 30 min reperfusion. The experimental indices included cardioplegic efficiency, cardiac function, coronary blood flow, myocardial enzyme release, myocardial water and ATP content. Hyperpolarized arrest provided significantly better recovery of cardiac function than depolarized arrest. Postischemic coronary flow and myocardial ATP content were higher. The arrest time of electro-mechanical activities were longer than depolarized arrest. There were no differences among the groups in myocardial water contents. The hyperpolarized arrest solution containing pinacidil can provide a marked myocardial protective effect during prolonged hypothermic myocardial ischemia.
Animals ; Cardioplegic Solutions ; pharmacology ; Cyclic Nucleotide-Gated Cation Channels ; Heart Arrest, Induced ; Hyperpolarization-Activated Cyclic Nucleotide-Gated Channels ; In Vitro Techniques ; Ion Channels ; metabolism ; Male ; Myocardial Reperfusion Injury ; physiopathology ; prevention & control ; Myocardium ; metabolism ; Pinacidil ; pharmacology ; Potassium Channels ; Random Allocation ; Rats ; Rats, Wistar