Yoshihiro Hanaki

Adverse effects of anti-tumor drug, cisplatin, on rat kidney mitochondria: Disturbances in glutathione peroxidase activity

This study was designed to clarify mechanisms responsible for cisplatin-induced nephrotoxicity together with the effect of selenium. Rats were divided into 3 groups: the cisplatin group; cisplatin (60 mg/kg) was administered intraperitoneally once, the cisplatin + Se group; cisplatin (60 mg/kg) once, and selenious acid (10 mumol/kg) were administered intraperitoneally once a day for 5 consecutive days, the control group; untreated. In each group, mitochondrial respiratory function, enzymic activities in mitochondrial respiratory chain and glutathione peroxidase, and plasma creatinine and BUN contents were measured. In the cisplatin group, decreases in mitochondrial respiratory function, enzymic activities in the respiratory chain and glutathione peroxidase, and increases in plasma creatinine and BUN contents were observed compared with the control group, while the cisplatin + Se group lessened these impairments. These results suggested that cisplatin-induced nephrotoxicity was closely related to mitochondrial dysfunction through the impairment of glutathione peroxidase. This toxicity might be ascribed to free radical mediated-injury. We propose here that, with selenium, higher dose administration of cisplatin to patients might be applicable.

PROTECTIVE EFFECT OF COENZYME Q10 ON EXERCISE-INDUCED MUSCULAR INJURY

The effect of coenzyme Q10 administration on exercise-induced muscular injury was examined in rats. Coenzyme Q10-treated and control rats were exercised by 90 min of downhill treadmill running. A part of the animals in both groups were killed immediately after exercise and the others were 40 h postexercise. After the exercise bout, serum creatine kinase and lactate dehydrogenase activities were elevated in the control rats, but not in the coenzyme Q10-treated rats. These enzyme activities in the latter increased to the similar level of the former 40 h postexercise. The muscle coenzyme Q10 content increased by the coenzyme Q10 treatment. These results suggest that the coenzyme Q10 treatment protected skeletal muscles against injury caused during exercise, but not against damage related with inflammatory processes after exercise.

The role of leukotoxin (9,10-epoxy-12-octadecenoate) in the genesis of coagulation abnormalities.

This study was designed to clarify whether or not leukotoxin (9, 10-epoxy-12-octadecenoate), which is biosynthesized by neutrophils, might be involved in the genesis of coagulating abnormalities. Twelve dogs were divided into 2 groups. In the test group (n = 6), 100 mumol/kg of leukotoxin was injected intravenously, and in the control group (n = 6), 100 mumol/kg of linoleate was injected. In each group, a series of blood samples were collected and used for coagulation studies. After the end of the experimental period, a histological study was performed on organs removed from the dogs. In the leukotoxin group, fibrin and fibrinogen degradation products (FDP) was increased time-dependently. Fibrinogen was decreased, and prothrombin time and activated partial thromboplastin time were prolonged in parallel with the increase in FDP. A decrease in number of platelets was also observed. Intravascular coagulation was observed in sections of lung. These data were compatible with a diagnosis of disseminated intravascular coagulation (DIC). No significant changes in these parameters were observed in the linoleate group. Leukotoxin has been confirmed to show antifungal and antibacterial activity, and its production might be a defensive response to infection. Over-production of leukotoxin associated with severe infection might therefore account for infection-induced DIC.

Cardioprotective effects of various class I antiarrhythmic drugs in canine hearts

This study was designed to clarify the cardioprotective effects of various class I antiarrhythmic drugs, i.e., aprindine, disopyramide, flecainide, lidocaine, mexiletine, pentisomide and propafenone, on the ischemic heart. Sixty-one adult mongrel dogs were classified into eight groups according to premedication: 1) control group, physiologic saline solution was administered intravenously 25 min before left anterior descending coronary artery ligation; 2) aprindine group, 3 mg/kg body weight of aprindine intravenously; 3) disopyramide group, 2 mg/kg of disopyramide intravenously; 4) flecainide group, 2 mg/kg of flecainide intravenously followed by drip infusion of 100 micrograms/kg per min; 5) lidocaine group, 2 mg/kg of lidocaine intravenously followed by drip infusion of 100 micrograms/kg per min; 6) mexiletine group, 3 mg/kg per min of mexiletine intravenously followed by drip infusion of 15 micrograms/kg per min; 7) pentisomide group, 5 mg/kg intravenously; and 8) propafenone group, 2 mg/kg intravenously. Arterial blood pressure and electrocardiogram were monitored throughout the experiment. Two hours after coronary occlusion, the heart was excised. Myocardial mitochondria were prepared and mitochondrial function (the respiratory control index and the rate of oxygen consumption in state III) was measured polarographically. Fractionation of myocardial tissues was performed and the lysosomal enzyme (N-acetyl-beta-glucosaminidase and beta-glucuronidase) activities among fractions were measured. No significant hemodynamic changes were observed compared with the control group except for those in the disopyramide and flecainide groups; that is, decrease in heart rate without changes in blood pressure compared with the control group was observed. All antiarrhythmic drugs effectively prevented the development of ventricular arrhythmias associated with ischemia.(ABSTRACT TRUNCATED AT 250 WORDS)

New two-dimensional, echocardiographically directed pericardiocentesis in cardiac tamponade

Seventeen patients with cardiac tamponade were treated by pericardiocentesis guided by two-dimensional (2-D) echocardiography and a needle guide. The needle guide used in the present study was designed so that the needle path lies within the center of the scan thickness. Before actual puncture, the mask method was performed in a water bath so that the needle progress avoided injury. The needle progress was monitored continuously in real time on the display throughout the procedure. Immediate relief from acute cardiac tamponade was obtained in all except one patient, who was treated by pericardiotomy because of insufficient drainage. In two patients, second drainage was performed because of reaccumulation of the pericardial effusion. There were no major complications. Nine patients recovered and the other patients died of underlying disease. Accurate and efficient visualization of the needle might allow a safer procedure. We conclude that pericardiocentesis guided by 2-D echocardiography using a needle guide may be a safe and easily applied technique for the management of pericardial effusion.

Effects of antiarrhythmic agents classified as class III group on ischaemia‐induced myocardial damage in canine hearts

1 The cardioprotective effects of antiarrhythmic agents classified as class III, amiodarone, sotalol and E‐4031, were investigated in anaesthetized dogs. 2 The left anterior descending coronary artery was occluded for 2 h. 3 Heart mitochondria were prepared from both the ischaemic and non‐ischaemic areas, and their function was estimated polarographically. 4 Activities of the lysosmal enzymes, N‐acetyl‐β‐glucosaminidase and β‐glucuronidase, were measured in each fraction. 5 Two hour occlusion induced ventricular arrhythmias, and amiodarone, sotalol and E‐4031 greatly suppressed the development of arrhythmias. 6 Amiodarone, sotalol and E‐4031 significantly protected mitochondria against ischaemia, and prevented ischaemia‐induced leakage of lysosomal enzymes. 7 Antiarrhythmic agents classified as class III show cardioprotective effects, which might participate in their antiarrhythmic effect.

The effects of SUN 1165, a novel sodium channel blocker, on ischemia-induced mitochondrial dysfunction and leakage of lysosomal enzymes in canine hearts.

The cardioprotective effect of SUN 1165, a novel sodium channel blocker, was investigated on ischemic myocardium. Nineteen anesthetized dogs were subjected to 2 hours coronary occlusion, and divided into 2 groups. In the control group, physiological saline was infused. In the SUN 1165 group, 2 mg/kg of SUN 1165 was injected intravenously. Two hours after occlusion, heart mitochondria were prepared from both ischemic and non-ischemic areas in each group, and their functions (RCI and St.III O2) were measured polarographically with succinate as a substrate. Fractionation of myocardial tissue from both non-ischemic and ischemic areas was performed according to the method of Weglicki et al., and the activities of lysosomal enzymes (NAG and beta-gluc) were measured. In the control group, mitochondrial dysfunction and leakage of lysosomal enzymes induced by 2 hours occlusion were observed. Administration of SUN 1165 maintained mitochondrial function, and prevented the leakage of lysosomal enzymes caused by ischemia significantly. These results indicated that SUN 1165 has a cardioprotective effect in ischemic heart.

Role of acetylcholine in pyridostigmine-induced myocardial injury: possible involvement of parasympathetic nervous system in the genesis of cardiomyopathy

Although acetylcholine is known to be involved in the genesis of skeletal muscle disturbance, its effect on cardiac muscle has been scarcely studied. In the present paper, using pyridostigmine, a cholinesterase inhibitor, the possible role of acetylcholine in the genesis of cardiomyopathy was investigated. In a mortality study, it was shown that pyridostigmine (100 mg/kg) caused death of 9/10 rats within 8 h, and that the lethality of such a dose could be significantly diminished by the subsequent administration of a total dose of 4 mg/kg atropine. In all other experiments, rats were divided into three groups; the control, untreated group; the pyridostigmine + atropine group in which atropine (2 mg/kg) was administered 5 min after pyridostigmine (60 mg/kg) administration; and the pyridostigmine group in which pyridostigmine (60 mg/kg) was administered orally. Rats were killed 3 h after pyridostigmine administration, and hearts were isolated. Heart mitochondrial electron transport activity (NADH-cytochrome c reductase, succinate-cytochrome c reductase, and cytochrome c oxidase) were measured enzymatically, and mitochondrial respiratory rates and control indices were measured polarographically. Structural changes in cardiac muscles of each group were observed by electron microscopy of cardiac sections. Acetylcholine levels of left ventricle were measured by high performance liquid chromatography. Activities of NADH-cytochrome c reductase and succinate-cytochrome c reductase were not affected by pyridostigmine administration; however, cytochrome c oxidase activity was significantly reduced in the pyridostigmine group. Atropine markedly lessened this reduction in activity. A protective effect of atropine was also observed morphologically. In the pyridostigmine group and the pyridostigmine + atropine group, left ventricular acetylcholine levels were increased significantly compared with the control. The mitochondrial electron transport system plays a crucial role in cellular energy transduction. Hence mitochondrial dysfunction observed in rats treated with pyridostigmine could induce myocardial dysfunction. It is well known that cathecholamine is closely linked with the genesis of cardiomyopathy. We now propose here that acetylcholine might also be related to cardiomyopathy.

Acceleration of recovery of mitochondrial function after coronary reperfusion by various coronary dilating drugs in canine hearts.

This study was designed to evaluate whether or not increase in coronary blood flow after reperfusion accelerates the recovery of ischemia-induced mitochondrial damage. Using anesthetized dogs, the left anterior descending coronary artery was occluded for 30 min, followed by 20 min of reperfusion. Five minutes after reperfusion, either physiological saline (n = 9), 0.5 mg/kg of dilazep (n = 7), 0.2 mg/kg of diltiazem (n = 7), or 0.5 mg/kg of nicorandil (n = 8) were administered intravenously. Arterial blood pressure, heart rate, and coronary blood flow were measured throughout the experiment. Twenty minutes after reperfusion, heart mitochondria from normal and reperfused areas were prepared, and mitochondria) function was measured. Significant in-crease in coronary flow was observed during reperfusion in all drug-treated groups; however, no significant in-crease was observed in the control group 10 min after reperfusion. Significant hemodynamic changes were not observed in all groups. Mitochondrial function from reperfused areas was recovered significantly in all drug-treated groups, though in the control group mitochondrial dysfunction persisted. Coronary dilative mechanisms of drugs used here differ; however, a similar effect was demonstrated, i.e., administration of a coronary dilator accelerates the recovery of mitochondria after reperfusion. Therefore, it is concluded that coronary flow after reperfusion might be a primary factor in the recovery of ischemia-induced mitochondrial damage.

Differing time courses between Δlactate and mitochondrial respiration during coronary occlusion and after reperfusion in canine hearts

SummaryThe present study was designed to clarify whether or not a difference between arterial and venous lactate (Δlactate) levels is useful for evaluation of mitochondrial function in ischemia-reperfused myocardium. In the first experiment, 12 dogs were divided into 2 groups: 10-min occlusion of the left anterior descending coronary artery (LAD) followed by 10-min reperfusion, or 30-min occlusion followed by 40-min reperfusion, were performed. The lactate levels in the femoral artery and the great cardiac vein were measured enzymatically. ΔLactate was reversed immediately after occlusion. Ten min and 20 min were required for the recovery of Δlactate in the 10-min-occlusion with 10-min-reperfusion, and 30-min-occlusion with 40-min-reperfusion groups, respectively. In the second experiment, 36 dogs were divided into 6 groups: 10-min occlusion of LAD; 10-min occlusion with 10-min reperfusion; 30-min occlusion; and 30-min occlusion with 10-, 20-, or 40-min reperfusion were performed. Mitochondria from normal and occluded or reperfused areas were prepared, and the respiratory function of the mitochondria was measured polarographically. No significant decreases in the mitochondrial function were observed in the 10-min-occlusion, and 10-min-occlusion with 10-min-reperfusion groups. On the other hand, respiratory function of mitochondria was impaired by 30-min occlusion and was not improved by 10- or 20-min reperfusion. Significant recovery in the mitochondrial function was observed after 40-min reperfusion. That is, differing recovery time courses between Δlactate and the mitochondrial function were observed.