The effects of sodium concentration in reperfusion solution upon myocardial protection]

The effects of several sodium concentrations in reperfusion solution (RS) were studied. Experimental time course was as follows: 20 min working perfusion, 3 min cardioplegic infusion with St. Thomas Cardioplegic Solution followed by global ischemia for 33 min at 37.5 degrees C, 15 min early Langendorff reperfusion with various sodium concentrations modified with Krebs Henseleit Bicarbonate Buffer (KHBB) and 5 min late reperfusion with KHBB, followed by 20 min working perfusion. Percent recoveries of aortic flow and Creatine Kinase leakage showed that 110 mM sodium of RS possessed optimal protective properties with bell shaped dose response characteristics.     

The effects of magnesium concentration in reperfusion solution upon myocardial protection]

Experimental time course was as follows: 20 min working perfusion, 3 min cardioplegic infusion with St Thomas Cardioplegic Solution followed by global ischemia for 35 min at 37.5 degrees C, 15 min first Langendorff reperfusion with reperfusion solution (RS) with various concentrations of Mg and 5 min second reperfusion with KHBB, followed by 20 min working. Cardiac functions were measured during pre and post working perfusion and CK leakage were measured during reperfusion. Percent recoveries of aortic flow at the Mg concentration of 0, 0.6, 1.2, 3.0, 6.0, 12 mM were 21 +/- 5, 22 +/- 3, 48 +/- 2, 37 +/- 4, 28 +/- 3, 15 +/- 3 (%) (mean +/- SEM), respectively. Our data indicated that 1.2 mM Mg of RS possessed protective properties with bell shaped dose response characteristics.     

The effects of calcium concentration of reperfusion solution upon myocardial protection]

The effects of several calcium concentrations in reperfusion solution were studied. Experimental time course was as followed: 20 min working perfusion, 3 min cardioplegic infusion with St. Thomas cardioplegic solution (STS) followed by global ischemia for 30 min at 37.5 degrees C, 15 min early Langendorff reperfusion with reperfusion solution and 5 min late reperfusion with Krebs Henseleit bicarbonate buffer [( Calcium] = 2.5 mM), followed by 20 min working perfusion. Percent recoveries of aortic flow at the Ca concentration of 0, 0.1, 0.6, 1.2, 1.8, 2.5 mM were 0, 14 +/- 1, 43 +/- 4, 64 +/- 3, 55 +/- 2, 59 +/- 1 (%), respectively. Our data indicated that reperfusion solution with less than 1.2 mM calcium reduced the protective properties of STS.     

The effects of osmolarity in reperfusion solution upon myocardial protection]

The effects of several different osmolarity in reperfusion solution were studied. Experimental time course was as follows: 20 min working perfusion, 3 min cardioplegic infusion with St. Thomas Cardioplegic Solution (STS) followed by global ischemia for 33 min at 37.5 degrees C, 15 min early Langendorff reperfusion with different osmolarity by adding sucrose and 5 min late reperfusion with Krebs Henseleit bicarbonate buffer, followed by 20 min working perfusion. Percent recoveries of aortic flow showed that 290 mOsm/L in reperfusion solution possessed optimal protective properties with bell shaped dose response characteristics.     

The effects of Na movement on surgical myocardial protection: the role of the Na+-H+ exchange system and Na-channel in the development of ischemia and reperfusion injury.

OBJECTIVES: We investigated whether the Na+-H+ exchange inhibitor, HOE642 (Hoe), and/or the Na channel blocker, mexiletine (Mex), enhance a cardioprotective effect on St. Thomas' Hospital cardioplegic solution (STS) to clarify the mechanism by which intracellular Na+ is accumulated after cardioplegic arrest. MATERIALS AND METHODS: Isolated working rat hearts were perfused with Krebs-Henseleit bicarbonate buffer (KHBB). The hearts were then arrested with STS and subjected to normothermic global ischemia (30 min). This was followed by Langendorff reperfusion (15 min) and then a working reperfusion (20 min). In study A, we added Hoe (5, 10, and 20 microM), Mex (70 microM), or a combination of Hoe (20 microM) and Mex (70 microM), to STS. In study B, we added Hoe (20 microM), Mex (70 microM), or a combination of Hoe (20 microM) and Mex (70 microM) to KHBB during the first 3 min of Langendorff reperfusion. RESULTS: In study A, the addition of Hoe (10 and 20 microM) to STS showed a significantly greater postischemic recovery of cardiac output compared to the control group [63.1+/-5.7% (10 microM), 62.7+/-4.7% (20 microM), and 55.5+/-4.6% (control), respectively]. The postischemic recovery of cardiac output was significantly greater in the group of the combined addition (Hoe and Mex) to STS than that in the control, 20 microM Hoe, 70 microM Mex groups [70.3+/-3.7 (Hoe and Mex), 55.5+/-4.6% (control), 62.7+/-4.7% (Hoe 20 microM), and 60.2+/-4.7% (Mex 70 microM), respectively]. The myocardial water content in the postischemic period was 565.1+/-29.1, 525.8+/-2.9, 509.4+/-19.6, and 532.2+/-20.1; it was 497.3+/-9.1 mL/100 g dry weight in the control; and 10 microM Hoe, 20 microM Hoe, and 70 microM Mex in the combined use groups. In study B, there was no significant difference in the postischemic recovery of cardiac output in all experimental groups. CONCLUSION: The combined use of the Na+-H+ exchange inhibitor and Na+ channel blocker during cardioplegia may achieve a superior cardioprotective effect on myocardial damage because of ischemia and reperfusion.     

2-Nicotinamidoethyl nitrale (2-NN) protects myocardium in ischemia and reperfusion via the protein kinase C pathway

BACKGROUND: Several recent studies have suggested an ATP-sensitive potassium channel opener (2-nicotinamidoethyl nitrate: 2-NN) may exert a protective effect against the myocardial ischemic/reperfusion injury. This study examines the effects of 2-NN on intracellular signaling by measuring intracellular cyclic AMP, cyclic GMP accumulation and protein kinase C (PKC) activity after 2-NN perfusion. METHODS: Ischemia/reperfused hearts were made by LAD occlusion for 30 min followed by 30 min of reperfusion in isolated rat hearts. Hearts were pre-perfused with 0.1 mM 2-NN, 100 nM Calphostin C, or 2-NN plus Calphostin C for 10 min prior to ischemia. The left ventricular function, cyclic AMP, cyclic GMP and LDH were examined to determine the effects of 2-NN on ischemic/reperfusion injury. Four separate groups of hearts were stained with a bisindolylmaleimide PKC inhibitor conjugated to fluorescein (fim, Teflabs) and PKC activity was measured. RESULTS: 2-NN reduced ischemia/reperfusion injury as evidenced by the enhanced myocardial functional recovery, decreased LDH release after reperfusion, and decreased reperfusion arrhythmias. The PKC inhibitor attenuated myocardial functional recovery but not reperfusion arrhythmias. Cyclic AMP levels decreased after 10 min of 2-NN perfusion, compared to controls. We observed an increase in PKC activity after 2-NN treatment. CONCLUSIONS: These results suggest that PKC plays a significant role in the cardioprotective effect of 2-NN on ischemic and reperfused myocardium. The anti-arrhythmic effect of 2-NN in the reperfusion phase may be linked its action on the ATP-sensitive potassium channel itself rather than its effect on PKC activity.     

The consequences of asanguineous versus sanguineous reperfusion after long-term preservation of the heart

We have used the heterotopically transplanted rat heart to investigate whether the nature (sanguineous or asanguineous) of the initial period of reperfusion after hypothermic cardioplegic storage influences the postischaemic recovery of the heart. Excised rat hearts were arrested by infusion (1 min at 25 degrees C followed by 2 min at 7.5 degrees C) with the St Thomas' Hospital cardioplegic solution, subjected to 4 h of storage at 7.5 degrees C and heterotopically transplanted over a fixed period of 45 min. Reperfusion was then carried out for 80 min according to one of the following protocols: 60 or 20 min of blood perfusion in situ followed by excision, and 20 or 60 min of in vitro perfusion with crystalloid solution (Groups I and II, respectively) or immediate excision and 80 min of crystalloid perfusion (Group III). Intraventricular balloons were used to define pressure-volume relationships at the end of the 80 min period of reperfusion. Tissue samples were then taken for assessment of water content, adenosine triphosphate (ATP) and creatine phosphate (CP) content. Mean left ventricular developed pressure (at a loading volume of 110 microliters) was 92 +/- 6, 79 +/- 6 and 51 +/- 6 mmHg in Groups I, II and III, respectively. Left ventricular end-diastolic pressure was lower in the initial blood reperfusion groups (25 +/- 4 and 21 +/- 3 mmHg in Group I and II, respectively, compared with 37 +/- 5 mmHg in Group III).(ABSTRACT TRUNCATED AT 250 WORDS)     

The effects of protease inhibitor upon the ischemia-reperfusion injury]

The purpose of the study is to investigate the effects of protease inhibitor (Nafamostat mesilate: NM) upon myocardial protection. Hearts were subjected to 20 min working control perfusion followed by 3 min cardioplegic infusion with the St. Thomas Cardioplegic Solution (ST) contained various concentrations of NM, and global ischemia for 33 min at 37 degrees C (Exp. 1) or 150 min at 20 degrees C (Exp. 2). Hearts were then converted to Langendorff reperfusion (the leakage of Creatine Kinase (CK) and Cathepsin B (Cat-B) ware measured) and 20 min working reperfusion. Various concentrations of NM added during Langendorff reperfusion (Exp. 3). During working perfusion cardiac functions (aortic flow (AoF), coronary flow (CoF), heart rate (HR), aortic pressure (AoP)) were measured, and expressed as the percent recovery of pre-ischemic control value. Post-ischemic recovery of AoF (%AoF) showed the bell-shaped dose-response curve, and the optimal dose was 3 microM (Exp. 1) and 10 microM (Exp. 2) respectively. There was a significant (p < 0.05) increase of %AoF in optimal dose compared with that in controls (64.2 +/- 1.2% vs 52.3 +/- 2.5% in Exp. 1, 68.9 +/- 3.1% vs 54.1 +/- 1.4% in Exp. 2). These increase of functional recovery reflected in the values for CK and Cat-B leakage. The addition of NM in ST reduced CK and Cat-B leakage significantly in the concentration of 5 microM (in Exp. 1) and 10 microM (in Exp. 2) respectively. But the addition of NM in reperfusate did not reduced CK leakage significantly.(ABSTRACT TRUNCATED AT 250 WORDS)     

Decreasing sarcoplasmic reticular calcium gives rise to myocardial protection? —The effect of thapsigargin for myocardial protection under conditions of normothermia—

Deceasing sarcoplasmic reticular (SR) calcium may contribute to the myocardiac protection against ischemia and reperfusion-induced injury. Therefore, using the isolated working rat heart model, we investigated the effect of Thapsigargin (TH)-induced SR calcium diminution on the myocardial protection when added either before onset of ischemia or at time of reperfusion under conditions of normothermic ischemia. Hearts (n=6/group) from male Wistar rats were aerobically (37°C) perfused (20 min) with bicarbonate buffer. In the experimental protocol A, this was followed by a 3 min infusion of St. Thomas’ Hospital cardioplegic solution No. 2 (STS) containing various concentrations of TH. Hearts were then subjected to 34 min of normothermic (37°C) global ischemia and 35 min of reperfusion (15 min Langendorff, 20 min working). Reperfusion cardiac functions at 20 min of working perfusion was measured and compared with the preischemia values. STS added to 0.1 and 0.25 μmol/L TH improved recovery of aortic flow after 20 min reperfusion from 47 ± 3% in the TH free controls to 62 ± 3, 63 ± 2% (n=6) (p<0.05). There was no difference in creatine kinase (CK) leakage during Langendorff reperfusion between the TH treated groups and the control group. In the experimental protocol B, 3 min of cardioplegia without TH and 34 min of ischemia (37°C) were followed by a 10 min Langendorff reperfusion with various concentrations of TH, then 10 min Langendroff reperfusion for washing out, and 20 min working reperfusion. When TH was added to reperfusate the recovery of aortic flow did not change. 0.5 μmol/L TH group had the detelious effect. Thus, TH, when added to the cardioplegia, enhanced myocardial protection. We conclude that lessened uptake of Ca²⁺ into sarcoplasmic reticulum by inhibitors of the Ca²⁺-ATPase pump can decrease ischemia and reperfusion-induced injury.     

Functional and metabolic effects of nicardipine on ischemic rat hearts with multidose potassium cardioplegia

This study was undertaken to assess the effect of a calcium antagonist, nicardipine (N), added in a cardioplegic solution on the ischemic myocardium. Isolated rat hearts were perfused with oxygenated Krebs Ringer Bicarbonate (KRB) solution by Langendorff's perfusion method and were subjected to 2 hours of ischemic arrest at 30 degrees C with multidose cardioplegia (every 30 min, for 5 min) and a subsequent 60 min of reperfusion. HR, LVP, coronary flow and oxygen tension of coronary effluent were monitored. Oxygen saturation of intracellular myoglobin and redox state of mitochondrial cytochrome aa3 in the myocardial cell were continuously measured throughout studies by a spectrophotometer. Oxygenated crystalloid cardioplegic solution (KRB) containing 25 mM of potassium was used. 40 rats were divided into 4 groups (10 rats each) according to the concentration of N (none, 0.5, 1 and 2 mg/L) in fully oxygenated potassium cardioplegic solution (PO2: 601 +/- 31 mmHg). The percent recovery of pressure-rate product after reperfusion was compared in each group and the optimal concentration of N was found to be 1 mg per liter of cardioplegic solution. No significant difference was found between Group Ia (N = 0 mg/L) and Group Ib (N = 1 mg/L) in metabolic or hemodynamic recovery after reperfusion. In other experiments, 40 rats in Group IIa (N = 0 mg/L, n = 20) and Group IIb (N = 1 mg/L, n = 20) received 10 ml of poorly oxygenated cardioplegic solution (PO2: 215 +/- 10 mmHg) on each reinfusion followed by a 25 min interval of ischemic arrest. The index of oxygen utilization, MVO2/pressure-rate product after reperfusion was significantly lower in Group IIb than in Group IIa (p less than 0.05). The results show that the addition of N (1 mg/L) to the cardioplegic solution preserved a more aerobic state (higher intracellular oxygen level) in the myocardium by further suppressing myocardial oxygen demand during the ischemic period which resulted in better myocardial protection. Therefore, it is concluded that the addition of N to the cardioplegic solution enhances myocardial preservation during myocardial ischemia.     

吡那地尔超极化停搏对大鼠离体心脏缺血再灌注时p38MAPK表达的影响

目的 评价吡那地尔超极化停搏对大鼠离体心脏缺血再灌注时p38丝裂原活化蛋白激酶(p38MAPK)表达的影响.方法 成年雄性SD大鼠48只,体重250～300 g,采用随机数字表法,将大鼠随机分为6组(n=8):自然停搏组(A组)、St.Thomas组(B组)、吡那地尔超极化停搏组(C组)、5-羟葵酸(5-HD)组(D组)、HMR-1098组(E组)和5-HD+HMR-1098组(F组).采用Langendorff离体心脏灌注模型,K-H液平衡灌注15 min后,A组阻断主动脉,不予停搏液灌注,使其自然停搏;B组灌注St.Thomas停搏液;C组灌注吡那地尔超极化停搏液;D组、E组和F组K-H液平衡灌注10 min后,分别灌注含5-HD、HMR-1098、5-HD+ HMR-1098的K-H液5min,再灌注吡那地尔超级化停搏液.心脏停跳缺血60 min后,K-H液再灌注30 min.于平衡灌注15 min和再灌注20 min时记录冠脉流量(CF)、心率(HR)、左室发展压(LVDP)、左室收缩压(LVSP)和左室压力瞬时最大变化率(dp/dtmax);于再灌注30 min时取心肌组织,采用Western blot法测定心肌磷酸化p38MAPK和非磷酸化p38MAPK的表达.结果 与C组相比,A组、B组、D组、E组和F组再灌注20min时CF、HR、LVSP、LVDP及dp/dt/dymax降低,再灌注30 min时磷酸化p38MAPK表达下调,非磷酸化p38MAPK表达上调(P＜0.05);与E组相比,D组和F组再灌注20 min时CF、HR、LVSP、LVDP及dp/dtmax降低,再灌注30 min时磷酸化p38MAPK表达下调,非磷酸化p38MAPK表达上调(P＜0.05).结论 吡那地尔超极化停搏可改善大鼠离体缺血再灌注心脏功能,其机制与上调磷酸化p38MAPK表达,下调非磷酸化p38MAPK表达有关,而这种调控作用与线粒体ATP敏感性钾通道关系更密切.     

Electrolyte and pH dependence of heart rate during hemodialysis: a computer model analysis

The influence of hemodialysis-induced modifications in extracellular fluid characteristics on heart rate was investigated by using a detailed computer model of sinus-node electrical activity. Changes similar to those occurring in the course of hemodialysis in extracellular concentrations of sodium (from 138 to 140 mM), potassium (from 6 to 3.3 mM), and calcium (from 1.2 to 1.5 mM) ions as well as in pH (from 7.31 to 7.4) and intracellular volume were simulated. The model predicted that such changes may largely influence the rhythm of the sinoatrial node pacemaker, causing the heart rate to range from 69 to 86 bpm. Heart rate increases after removing potassium (up to 7 bpm) and also after calcium perfusion (up to 11 bpm) whereas restoring pH slows heart beat (up to 6 bpm). Extracellular sodium has no significant influence, but the heart rate strictly depends on intracellular sodium concentration (5 bpm/mM). A complex dependence of heart rate on electrolytes and pH was also recognized. Providing extracellular potassium concentration is maintained above 5 mM, heart rate exhibits low sensitivity to changes in calcium and potassium. When potassium concentration is reduced below 4.5 mM, heart rate sensitivity to calcium and potassium increases significantly to 10 and 30 bpm/mM, respectively. A sustained increase in heart rate always corresponds to an increase in intracellular sodium concentration.     

Effect of initial reperfusion temperature on myocardial preservation

The effect of initial postischemic reperfusion temperature on myocardial preservation was studied in the isolated working rat heart model. After baseline measurement of aortic flow rate, coronary flow rate, and heart rate, 40 hearts were subjected to 60 minutes of ischemic arrest at 15 degrees C induced with a single dose of cold potassium cardioplegic solution. Hearts were then revived with a 10 minute period of nonworking reperfusion at 28 degrees, 31 degrees, 34 degrees, or 37 degrees C (10 hearts each), followed by 5 minutes of nonworking reperfusion at normothermia, followed by 30 minutes of working perfusion. Repeat measurements of function were obtained and postischemic release of creatine kinase into coronary effluent was determined. Recovery of aortic flow was significantly reduced at lower initial reperfusion temperatures (75% at 28 degrees C versus 88% at 37 degrees C) and the effect was approximately linear throughout the range studied (p less than 0.05). Release of creatine kinase into coronary effluent was greater at lower initial reperfusion temperatures (421 ImU/min/gm wet weight at 28 degrees C versus 115 ImU/min/gm wet weight at 37 degrees C), also in a linear manner (p less than 0.05). In this model, initial postischemic hypothermic reperfusion is deleterious to cellular integrity and functional recovery of the preserved myocardium. Studies in higher animals and humans are warranted to further evaluate the effect of initial reperfusion temperature on myocardial preservation.     

Effect of the potassium-channel opener nicorandil as an adjunct to cardioplegia on myocardial preservation in isolated rabbit hearts

We studied the effect of nicorandil on the hemodynamic, biochemical, and ultrastructural changes in rabbit hearts (n=50) rendered cardioplegic with a single injection of Bretschneider's HTK solution over 30min or 60min at 37°C or 15°C, followed by reperfusion at 37°C for 60min. Particular attention was focused on the aspects of doseresponse relationship, temperature sensitivity, and ischemic tolerance. Isolated hearts were prepared for modified Langendorff circulation using modified Krebs-Henseleit bicarbonate solution bubbled with a 95% O₂-5% CO₂ gas mixture, to which nicorandil (0, 0.1, 1, and 5 mM) was added. The optimal concentration of nicroandil was 1 mM, which increased the recovery of left ventricular (LV) function, affecting coronary flow and the myocardial cyclic adenosine monophosphate, but not the myocardial concentrations of adenine nucleotide compounds or total calcium. These effects were abolished by the addition of glibenclamide to the HTK, but they were not diminished by a high potassium (K⁺) concentration of 20 mM. The addition of nicorandil 1 mM to the HTK at 15°C did not improve the recovery of LV function. Our result suggested that nicorandil used adjunctly prevents LV functional depression after 30 min, and possibly 60 min of cardioplegia at 37°C, and that this effect is not disturbed by a high K⁺ concentration up to 20 mM. However, nicorandil has temperature sensitivity whereby it loses its efficacy at 15°C.     

Repetitive brief ischemia: intermittent reperfusion during ischemia ameliorates the extent of injury in the perfused kidney

Acute renal failure commonly follows reduced renal perfusion or ischemia. Reperfusion is essential for recovery but can itself cause functional and structural injury to the kidney. The separate contributions of ischemia and of reperfusion were examined in the isolated perfused rat kidney. Three groups were studied: brief (5 min) ischemia, 20 min ischemia, and repetitive brief ischemia (4 periods of 5 min) with repetitive intervening reperfusion of 5 min. A control group had no intervention, the three ischemia groups were given a baseline perfusion of 30 min before intervention and all groups were perfused for a total of 80 min. In addition, the effects of exogenous *NO from sodium nitroprusside and xanthine oxidase inhibition by allopurinol were assessed in the repetitive brief ischemia-reperfusion model. Brief ischemia produced minimal morphological injury with near normal functional recovery. Repetitive brief ischemia-reperfusion caused less functional and morphological injury than an equivalent single period of ischemia (20 min) suggesting that intermittent reperfusion is less injurious than ischemia alone over the time course of study. Pretreatment with allopurinol improved renal function after repetitive brief ischemia-reperfusion compared with the allopurinol-untreated repetitive brief ischemia-reperfusion group. Similarly, sodium nitroprusside reduced renal vascular resistance but did not improve the glomerular filtration rate or sodium reabsorption in the repetitive brief ischemia-reperfusion model. Thus, these studies show that the duration of uninterrupted ischemia is more critical than reperfusion in determining the extent of renal ischemia-reperfusion injury and that allopurinol, in particular, counteracts the oxidative stress of reperfusion.     

Halothane reduces dysrhythmias and improves contractile function after global hypoperfusion in isolated hearts.

We investigated the effects of halothane on changes in cardiac function during hypoperfusion and recovery of function after reperfusion in the isolated perfused guinea pig heart. Heart rate, atrioventricular (AV) conduction time, the incidence and severity of dysrhythmias, and isovolumetric left ventricular systolic pressure (LVSP) and its derivative were measured. Hearts (n = 85) were divided into three groups for 30 min of perfusion at 0% (no flow), 10%, and 25% of the control perfusion pressure (PP, 55 mm Hg). These groups were subdivided and exposed to 0%, 0.74% (0.23 +/- 0.01 mM), or 1.65% (0.51 +/- 0.01 mM) halothane 10 min before, during, and 10 min after hypoperfusion. Hypoperfusion was followed by 40 min of reperfusion at control PP. Exposure to 0.74% and 1.65% halothane before hypoperfusion produced a 9% and 13% decrease in heart rate, a 2% and 30% increase in AV conduction time, and a 25% and 51% decrease in LVSP and dLVP/dtmax, respectively. During the 30 min of hypoperfusion, heart rate decreased and AV conduction time increased; second- and third-degree AV block occurred in all hearts in the 0% and 10% PP groups, but only in some hearts in the 25% PP groups. Left ventricular systolic pressure rapidly decreased during hypoperfusion in all groups. During early reperfusion ventricular fibrillation and ventricular tachycardia occurred in the 0% and 10% PP groups but not in the 25% PP groups. During reperfusion 0.74% and 1.65% halothane greatly reduced the duration of ventricular fibrillation from 8.1 +/- 3.3 min to 1.5 +/- 0.8 and 1.9 +/- 1.2 min in the 0% and 10% PP groups, respectively. A concentration of 0.74% halothane increased the incidence of supraventricular tachycardia on reperfusion in the 10% group (from a control of 20% to 65%), and 1.65% halothane increased the duration (2.6 +/- 2.5 min) and incidence (38%) of supraventricular tachycardia on reperfusion in the 0% PP group. A concentration of 1.65% halothane facilitated recovery of LVSP after hypoperfusion in the 25% group but not in the 0% and 10% PP groups. These results indicate that halothane, in some instances, can have protective cardiac effects after graded hypoperfusion as assessed by improved contractility and by reduced severity of some dysrhythmias during reperfusion; however halothane may also increase the incidence of supraventricular tachycardia. The cardiac protection by halothane could be a result of reduced cardiac work before, during, and after hypoperfusion, or of some other direct protective cellular effects.     

Adenine nucleotide catabolism in human myocardium during heart and heart-lung transplantation.

The influence of ischemia and reperfusion on nucleotide concentration in human myocardium was investigated during heart and heart-lung transplantation. Myocardial preservation during heart transplantation was achieved by infusion of cold St. Thomas' Hospital cardioplegic solution followed by storage in Ringer's solution at 4 degrees C during transport. In contrast, the hearts of heart and lung donors were preserved by core cooling using cardiopulmonary bypass and infusion of cold blood cardioplegia containing 26 mM potassium. The heart-lung block was transported in cold donor blood. Nucleotides and their catabolite concentrations were measured in donor tissue specimens taken before organ collection, before commencement of implantation and 30 min after aortic clamp removal. During reperfusion, samples of coronary sinus and arterial blood were collected and analysed for nucleotide catabolite concentration. Myocardial ATP and total nucleotide pool remained almost unchanged during the ischemic transport of the donor organs with only very small increases in myocardial inosine and hypoxanthine concentrations. However, a significant decrease of total adenine nucleotide pool by 10%-20% was demonstrated between the start of implantation and 30 min post-reperfusion. A release of inosine + hypoxanthine was greatest in the 1st minute (15-25 microM), but was still substantial after 10 min of reperfusion (5-15 microM). Metabolic changes tended to be more pronounced during heart-lung transplantation than during heart transplantation.     

Performance of pig heart after 30 or 120 minutes hypothermic arrest

The effect of the duration of hypothermic (T = 15°C) potassium cardioplegic arrest and ischemia on the heart was determined by measuring the response of the isolated in situ pig heart to 180 min of perfusion (n = 12) to provide appropriate control values for the study of 30 (n = 25) or 120 (n = 27) min of ischemia, followed by 60 min of reperfusion. In some of these animals, myocardial tissue samples were obtained for measurement of adenosine triphosphate (ATP) and creatine phosphate (CP), (6 in the perfusion group, 7 in the 30 min of ischemia and 60 min of reperfusion group and 15 in the 120 min of ischemia and 60 min of reperfusion group). In the remaining animals, measurements of either left ventricular performance (LVP), myocardial oxygen metabolism (MV?O₂) or plasma creatine kinase (CK) were obtained (6 in the prolonged perfusion group, 12 in the 120 min of ischemia and 60 min of reperfusion group, [6 LVP and MV?O₂ and 6 CK] and 18 in the 30 min of ischemia and 60 min of reperfusion group [13 LVP, 17 MV?O₂ and 6 CK]). During prolonged perfusion, left ventricular performance, expressed as developed pressure, ΔP, fell from an initial value of 175 ± 36 to 128 ± 19 mm Hg at 30 min of perfusion, followed by a more gradual decline to a final value of 113 ± 8 mm Hg at 180 min of perfusion. These decreases were not significantly lower than the initial value. The percentage of myocardial extraction declined in a similar manner, but coronary blood flow was constant over this interval. The primary effect of 30 or 120 min of ischemia was to reduce left ventricular developed pressure, ΔP, during reperfusion to more than 70% of the corresponding value in the control group (these differences were statistically significant) which suggests that prolonging the period of ischemia did not cause further deterioration of cardiac performance. The plasma concentration of CK rose in the control group of hearts subjected to prolonged perfusion from an initial value of 35 ± 6 to a final value of 59 ± 8 IU/liter (P < 0.05). While plasma CK increased during reperfusion in both ischemia/ reperfusion groups, these values were not significantly higher from prearrest values. Thus hypothermic cardioplegic ischemia of this duration did not appear to result in tissue necrosis, but there was a significant reduction in left ventricular performance which was independent of the duration of ischemia between the limits of 30 and 120 min.     

Epithelial Structure of the Rat Cauda Epididymidis after Luminal Perfusion

When solutions containing high concentrations of sodium ions (c. 140 mM) were perfused for up to 6 h through the lumen of the cauda epididymidis of the anaesthetised rat, distended spaces were consistently seen between the epithelial cells, water resorption was measurable, and clear cells lacked large clear apical vacuoles. Lowering the sodium ion concentration decreased water resorption, and distended intercellular channels were absent. Under these conditions clear cells had abnormally large or numerous pale staining vacuoles. When physiological concentrations of sodium (20 mM) and potassium (50 mM) ions were perfused, a more normal epithelium was present; intercellular channels were absent, and water was either resorbed or secreted at low rates. Clear cells appeared normal initially, but had abnormal appearance after longer periods of perfusion.     

Experimental myocardial preservation study of adding perfluorochemicals (FC43) in lidocaine cardioplegia.

OBJECTIVE: Lidocaine exhibits a cardioplegic action via acute inhibition of sodium influx into the myocardial cells. In terms of the cardiac function and calcium dynamics in the myocardial cells, we investigated the myocardial protective effect of addition of FC43 of Perfluorochemicals, which has an excellent oxygen transport function to meet the myocardial oxygen demand, on lidocaine-induced cardioplegia. METHODS: Isolated rat hearts were perfused with Langendorff mode and were divided to three experimental groups. During of preservation, these hearts were perfused continuously with the next three solution, potassium chloride was added to Krebs-Henseleit bicarbonate buffer to make potassium concentration of 20 mM in the first group (Group A), 2 mM lidocaine was added to Krebs-Henseleit bicarbonate buffer in the second group (Group B), and 2 mM lidocaine and 20% FC43 were added to Krebs-Henseleit bicarbonate buffer in the third group (Group C). After 60 minutes of continuous perfusion, the cardiac function and the intracellular calcium concentration in Groups A and B during cardioplegia were measured. Furthermore, after 360 minutes of continuous coronary perfusion, the cardiac function were measured in Group B and Group C. RESULTS AND CONCLUSIONS: Lidocaine cardioplegia showed a good recovery of cardiac function, because lidocaine induced prompt cardiac arrest by blocking sodium influx and inhibited the intracellular calcium overload by the following inhibition of sodium-calcium channels. Moreover, our results suggested that combining Perfluorochemicals with lidocaine produced a more effective myocardial-preservation that meets the myocardial oxygen demand during long-term cardiac arrest.