Prevention by fructose-1,6-bisphosphate of cardiac oxidative damage induced in mice by subchronic doxorubicin treatment.

An experimental model of mild, subchronic doxorubicin cardiotoxicity in mice was investigated by monitoring changes of biochemical parameters related to cell response against oxidative stress in both liver and heart. A specific increase of the lactate dehydrogenase isoenzyme typical of the heart was observed for doxorubicin-treated mice. Lipid peroxidation, as evaluated by malondialdehyde determination, and catalase activity were greatly increased in heart and unaffected in liver. On the other hand, these changes can be considered as indicative of early heart damage induced by doxorubicin. Glutathione, glutathione peroxidase, and 6-phosphogluconate dehydrogenase values were not significantly altered by the treatment and glucose-6-phosphate dehydrogenase increased in both liver and heart. Administration of fructose-1,6-bisphosphate strongly reduced the increase of plasma lactate dehydrogenase, heart lipid peroxidation, and heart catalase while no effect on the diagnostically irrelevant increase of glucose-6-phosphate dehydrogenase was observed. The inhibitory effect on the onset of biochemical modification typical of early subchronic doxorubicin cardiotoxicity may be related to stimulation of ATP synthesis by fructose-1,6-bisphosphate and is therapeutically promising in view of the lack of toxicity of fructose-1,6-bisphosphate as a drug.

Protective effect of exogenous fructose-1,6-diphosphate in cardiogenic shock.

The effect of intravenous fructose-1,6-diphosphate (FDP) infusion on haemodynamic and biochemical variables was studied in dogs after ligation of the anterior descending branch of the left coronary artery. In the control series cardiogenic shock was present in every case 4 h after ligation. In FDP treated animals 4 h after ligation there was no fall in cardiac output and the systolic blood pressure was restored to pre-ligation values. Levels of serum creatine kinase isoenzyme (CK-MB), a highly specific indicator of myocardial cell damage, rose in the shocked (no FDP given) group, but remained low in the FDP treated group, equalling the levels measured in sham operated (no ligation) dogs. Samples of myocardium were taken from infarcted and adjacent normal regions 4 h after ligation for biochemical analysis. CK-MB concentrations in the infarcted region did not change from normal levels with FDP infusion; in the infarcted region lactate concentration (mumol.g-1 wet weight) fell from 18.48 in the control group to 7.90 in the FDP treated group. ATP levels in the infarcted region remained the same as those in the adjacent normal region with FDP treatment. It is concluded that infusion of FDP improves myocardial performance and metabolism following acute myocardial ischaemia.

Fructose-1,6-bisphosphate protects astrocytes from hypoxic damage.

To determine the effects of glucose and fructose-1,6-bisphosphate (FDP) on hypoxic cell damage, primary cultures of astrocytes were incubated for 18 h in an air-tight chamber that had been flushed with 95% N2/5% CO2 for 15 min before it was sealed. Cultures containing 7.5 mM glucose without FDP or FDP without glucose showed evidence of significant cell injury after 18 h of hypoxia (increased lactate dehydrogenase content in the culture medium; cell edema and disruption by phase-contrast microscopy). Cultures exposed to glucose + FDP had normal lactate dehydrogenase concentrations and appeared normal microscopically. Maximal protection of hypoxic cells occurred at 6.0 mM FDP. Lactate concentrations of the culture medium of hypoxic cells increased 2.5 times above normoxic control values when glucose was present, but neither FDP alone nor glucose + FDP caused the lactate concentrations to increase further. This implies that anaerobic glycolysis was not increased by adding FDP to the medium. Cell volumes (water space) measured with [14C]-3-0-methyl-D-glucose were normal with glucose + FDP in the culture medium of hypoxic cells but were significantly larger than normal when glucose alone was present. Increases in cell volume paralleled changes in lactate dehydrogenase in the culture medium. Uptake of [14C]FDP occurred rapidly in normoxic cells and was maximal after 5 min of incubation. The data indicate that the presence of glucose + FDP in the culture medium protects primary cultures of hypoxic astrocytes from cell damage.(ABSTRACT TRUNCATED AT 250 WORDS)

A comparison between fructose 1,6-diphosphate, glucose, or normal saline infusions and species-specific blood exchange transfusions in the treatment of bowel ischemia.

Infusion of fructose 1,6-diphosphate, (FDP), the rate-limiting substrate in anaerobic metabolism, decreases infarction in the ischemic heart. This study evaluates the effect of FDP (5% in H2O), glucose (D5W), or normal saline (N/S) infusions and species-specific blood (SSB) exchange transfusions on mortality rates and bowel infarction in rats with intestinal ischemia. One hundred twenty Sprague-Dawley male rats (50 to 75 gm) were divided into six experimental groups. Group I controls (n = 20) underwent sham laparotomy. Group II (n = 20) underwent superior mesenteric artery (SMA) occlusion for 90 minutes. Group III rats (n = 20) were infused with FDP with SMA occlusion (90 minutes). Group IV rats (n = 20) were infused with D5W with SMA occlusion (90 minutes). Group V rats (n = 20) were infused with N/S with SMA occlusion (90 minutes). Group VI rats (n = 20) received species-specific exchange transfusion after SMA occlusion (90 minutes). A typical rat given 1 ml of D5W/75 gm had a serum glucose of 478 ng/dl with an osmolality of 293 mosm/L. After being given 1 ml of NS/75 gm, rats had a serum glucose level of 170 mg/dl with an osmolality of 291 mos/ml. Control rats had a serum glucose level of 139 mg/dl with an osmolality of 295 mosm/L. Survival at 48 hours without bowel infarction was 20 of 20 (100%) in group I, three of 20 (15%) in group II, 12 of 20 (60%) in group III, 12 of 20 (60%) in group IV, five of 20 (25%) in group V, and six of 20 (30%) in group VI (p less than 0.05 groups III and IV versus group II). FDP and D5W infusions increased survival after bowel ischemia in the rat. The mechanism of action may involve provision of a substrate for anaerobic metabolism to ischemic bowel via collateral pathways, hemodilution, and/or volume expansion.

Increasing survival of dogs subjected to hemorrhagic shock by administration of fructose 1-6 diphosphate.

Previous reports from this laboratory described animal experiments in which intravenous administration of fructose 1-6 diphosphate (FDP) at the onset of hypovolemia, toxemia, and trauma effected improvement in hemodynamic and metabolic parameters, attenuation of tissue damage, and a significant increase in survival. The obvious question remained: Would this agent be as effective if administered after the onset of the shock syndrome? Thus 72 anesthetized dogs were subjected to normotensive hemorrhagic shock and were subsequently treated with FDP at 30 minutes, 1 hour, 90 minutes, and 2 hours after exsanguination. Analysis of the results (as compared with vehicle-treated controls) revealed evidence of improved cardiac output and arterial pressure (p less than 0.02), conservation of effective circulatory volume, better oxygen utilization, and a significant increase in survival (p less than 0.0001). These results, in conjunction with earlier experimental and recent clinical data, indicate that the therapeutic effect of FDP in ischemic and hypoperfusion states is in part metabolically mediated by the augmentation of carbohydrate utilization. Prevention of tissue injury is in part due to the inhibition of generation of oxygen-derived free radicals by neutrophils.

Improved exercise tolerance by i.v. fructose-1,6-diphosphate in chronic, stable angina pectoris.

The effect of IV fructose-1,6-diphosphate (FDP) on transient, reproducible myocardial ischemia was evaluated in ten patients, aged 50 to 66 years, with chronic, stable exertional angina. FDP or placebo (glucose) were administered between basal and posttreatment ergometric stress testing; an identical procedure was repeated in each patient with the second treatment on the following day according to a single-blind, cross-over design. FDP improved exercise tolerance and total work capacity, significantly delaying the onset of ST-segment depression and angina. Nevertheless, the critical level of the rate x pressure (R X P) product, causing appearance of myocardial ischemia, was not remarkably changed. However, the R X P product at same workload was significantly lower after FDP. These results suggest that improved exercise tolerance might have resulted from peripheral (increased oxygen delivery to skeletal muscle) rather than from central (cardiac) effects of FDP.

Improved left ventricular function after short-term treatment with fructose-1,6-diphosphate: echocardiographic study in chronic ischemic heart disease and idiopathic dilated cardiomyopathy.

The effect of fructose-1,6-diphosphate (FDP) on left ventricular function was assessed in seven patients with chronic ischemic heart disease and eight patients with idiopathic dilated cardiomyopathy. In a crossover study design each patient received 10 gm of FDP or saline placebo intravenously for three days. An M-mode echocardiographic assessment of left ventricular (LV) function was made before and after each treatment period. After FDP treatment, LV end-diastolic and systolic dimensions showed a 6% reduction (P less than 0.01), while peak lengthening rate of LV dimension in diastole and peak shortening rate of LV dimension in systole increased 17% and 10%, respectively (P less than 0.05). There was evidence that FDP was more effective in the patients with ischemic heart disease than in the patients with cardiomyopathy.

Protective effects of fructose-1,6-diphosphate on acute and chronic doxorubicin cardiotoxicity in rats.

The effects of fructose-1,6-diphosphate, an intermediate metabolite of glycolysis, on acute and chronic cardiotoxicity of doxorubicin were investigated in rats. In the acute study, urethane-anaesthetized Wistar female rats treated with 10 mg/kg i.v. doxorubicin developed a widening of the S alpha T segment, an impairment of +dP/dtmax, and tachycardia. Pretreatment with 375 and 750 mg/kg i.p. fructose-1,6-diphosphate prevented the S alpha T segment from widening, whereas only 750 mg/kg i.p. significantly attenuated the heart rate increase. Chronic cardiomyopathy was induced over a 6-week period by weekly doses of 3 mg/kg i.v. doxorubicin, being characterized in vivo by the progressive enlargement of the S alpha T segment and the occurrence of histological alterations and in vitro by a marked impairment of the inotropic response elicited by adrenaline in isolated hearts from treated rats. Concurrent treatment with 150 and 300 mg/kg i.p. fructose-1,6-diphosphate thrice a week for 6 weeks did not lessen the chronic heart damage, whereas 600 mg/kg given i.p. significantly reduced the widening of the S alpha T segment and the severity of histological damage in vivo, as well as significantly improving the contractile responses of hearts in vitro. These findings suggest that the administration of fructose-1,6-diphosphate plays a protective role in the acute and chronic cardiotoxicity of doxorubicin in the rat.

Haemorheological effects of fructose-1,6-diphosphate in patients with lower extremity ischaemia.

A prospective, single-blind study was carried out in 30 patients with obstructive peripheral artery disease to investigate the haemorheological properties of fructose-1,6-diphosphate (FDP). Patients were allocated at random to receive 7 to 10-days' treatment with either 10 g or 10% FDP twice daily or saline. Measurements were made on entry and at the end of treatment of whole blood and plasma viscosity, erythrocyte deformability and aggregation, and lower limb blood flow was evaluated by Doppler technique. FDP treatment was associated with a reduction in whole blood viscosity (24%) and red blood cell aggregation index (27%), and an improvement in red blood cell deformability (42%) (p less than 0.01). No significant changes were observed in the control group. Plasma viscosity did not change in either treatment group. Limb blood flow increased (p less than 0.05) only in patients treated with FDP; the improvement was more pronounced in the most severely affected side (30%). No untoward events were observed or reported in any of the patients studied.

Effects of fructose 1,6-diphosphate on splanchnic artery occlusion shock in the rat.

Splanchnic artery occlusion (SAO) shock, produced by clamping splanchnic arteries for 45 min followed by the release of occlusion, was induced in male rats, treated 15 min before surgery, with fructose 1,6-diphosphate (FDP) or with equivalent doses of fructose or inorganic phosphate. Survival rate, peritoneal macrophage phagocytosis and plasma levels of myocardial depressant factor (MDF) were measured. Shocked animals pretreated with vehicle exhibited 24.6 +/- 0.9% phagocytic activity, 110 +/- 3.9 units/ml MDF plasma levels and 0% survival. Sham animals showed the following values: survival 100%; phagocytosis, 49.5 +/- 1.3%; MDF, 22 +/- 2.9 units/ml. Pretreatment with FDP (25 mg/kg/i.v.) significantly improved survival rate (50%) and macrophage phagocytosis (37.9 +/- 0.4%) and reduced plasma MDF levels (77 +/- 3 units/ml). Equivalent doses of fructose and inorganic phosphate did not improve survival, as well as lower doses of FDP. These results suggest a beneficial effect of FDP in SAO shock.

Cerebral resuscitation with succinate and fructose-1, 6-diphosphate.

To test the hypotheses that succinate or fructose-1, 6-diphosphate may have a beneficial effect in global cerebral ischemia, we induced complete global cerebral ischemia for 5 minutes in rabbits by occlusion of the ascending aorta and the superior and inferior vena cavae. Fifteen minutes after restoration of cerebral blood flow, animals received an intravenous bolus of either succinate or fructose-1,6-diphosphate followed by continuous infusion. Another group of animals received fructose-1, 6-diphosphate beginning prior to aortic occlusion. Control animals received intravenous glucose by bolus, followed by infusion. Cerebrospinal fluid lactate levels were measured before occlusion and at 2 1/2 hours after occlusion, when the animals were sacrificed. In all animals electrocortical silence was demonstrated for the 5 minutes of global ischemia. The percent change in cerebrospinal fluid lactate levels in all groups was statistically similar. Only two of seven of the control animals recovered electroencephalogram amplitude during the 2 1/2 hour observation period. Time for recovery of amplitude on the electroencephalogram in animals receiving fructose-1, 6-diphosphate either before or after ischemia was statistically similar to controls. In the succinate treated group, all seven animals regained preocclusion levels of electroencephalogram amplitude within 36 minutes of the restoration of cerebral blood flow. Succinate administered after complete global cerebral ischemia resulted in significantly increased recovery of cerebral electrical activity (Fischer's exact test, p less than 0.05).

[Fructose-1,6-diphosphate in the treatment of chronic heart failure].

Fructose-1,6-diphosphate (FDP) was given to 30 patients with chronic heart failure (CHF) caused by various kinds of heart diseases with the purpose to evaluate the effects of FDP on CHF patients. Definite hemodynamic and clinical improvement has been found in this group. CO increased by 1.61 +/- 0.31 L/Min (35%) (P less than 0.01) PCWP decreased by 5.5 +/- 1.08 mmHg (31%); mean PAP decreased by 5.8 +/- 2.07 mmHg (P less than 0.05). EF increased by 6.9 +/- 1.5 (15.1%) as shown by echocardiography and the peak effect of the drug appeared at 2 hours after administration. The results showed that FDP is effective in the treatment of heart failure, especially in patients with dysfunction of other organs.

[Effect of fructose-1,6-diphosphate on the size of the necrotic area and course of the acute period of experimental myocardial infarction in rats]. / Vliianie fruktozo-1,6-difosfata na razmery zony nekroza i techenie ostrogo perioda éksperimenta'lnogo infarkta miokarda u krys.

The experiments on rats indicated that fructose-1,6-diphosphate substantially decreased the sizes of a necrotic zone, elevated myocardial ATP levels, reduced the edematization of lung tissue, shortened the duration of early postocclusive arrhythmias, and increased the latent period for their development. A dose-dependent cardioprotective effect was found in the preparation.

[Effect of fructose-1,6-diphosphate and trental on the erythrocyte aggregating capacity in ischemic heart disease]. / Vliianie fruktozo-1,6-difosfata i trentala na agregatsionnuiu sposobnost' éritrotsitov krovi pri ishemicheskoi bolezni serdtsa.

It was shown that fructose-1.6-diphosphate was capable of marked suppression of the aggregation power of the blood erythrocytes of patients with acute myocardial infarction and angina of effort. The antiaggregation effect of the drug was dose-related and enhanced with an increase in the time of its contact with erythrocytes. The antiaggregation effect of pentoxifylline was not of distinct dose-related nature. Its antiaggregation power did not considerably depend on the time of incubation with erythrocytes.

Inability of fructose 1,6-diphosphate to reduce myocardial infarct size.

Fructose 1,6-diphosphate has been reported to reduce ischemic damage following coronary artery occlusion. To further evaluate fructose 1,6-diphosphate, we studied its effect on myocardial infarct size in open-chest, anesthetized dogs. Twenty min following left anterior descending coronary artery ligation, the animals received a constant infusion of either normal saline or fructose 1,6-diphosphate. Six hours following coronary artery ligation, the animals were killed and the hearts were sectioned from base to apex. Area at risk, infarct size, and infarct size expressed as a percentage of the area at risk were determined. Fructose 1,6-diphosphate had no effect on the amount of necrosis following coronary artery ligation. The area of necrosis expressed as a percentage of the left ventricle was similar in control (26 +/- 3%) and treated groups (24 +/- 4%). The area of necrosis expressed as a percentage of the area at risk was also similar in control and treated groups. Thus, in this model of myocardial ischemia, fructose 1,6-diphosphate does not reduce myocardial infarct size.

[Effects of fructose-1,6-diphosphate in patients with chronic ischemic heart disease. Echocardiographic study]. / Impiego del fruttosio-1,6-difosfato in pazienti con cardiopatia ischemica cronica. Studio ecocardiografico.

The effects of fructose-1,6-diphosphate (FDP) on cardiac activity were studied in 20 patients with chronic ischemic heart disease. Each patient received intravenously, in two different days, a single dose of FDP 20 g and placebo, according to a cross-over study design. Immediately prior to and ten minutes following each dosing, patients underwent an echocardiographic assessment. The comparison of pre- and post-treatment readings indicates that the diasto-systolic difference of left ventricular dimension increased by 10% after FDP (p less than 0.01). Similarly the increment of interventricular septum thickness increased by 16% (p less than 0.01) and that of posterior left ventricular wall thickness by 19% (p less than 0.01). In contrast the changes recorded after placebo treatment were far from being significant. These data indicate that the acute administration of a single dose of FDP may improve the cardiac performance in patients with chronic ischemic heart disease.

Fructose 1-6 diphosphate prevents intestinal ischemic reperfusion injury and death in rats.

This study of ischemic and postischemic reperfusion intestinal injury in rats evaluates the potential therapeutic value of fructose 1-6 diphosphate on the basis of its ability to enhance anaerobic carbohydrate metabolism during ischemia and to prevent additional tissue injury after reestablishing blood flow by inhibiting the neutrophils to produce oxygen free radicals. In pursuit of this goal, 28 rats were randomized into 4 groups: pretreated with fructose 1-6 diphosphate (n = 7); pretreated with glucose (n = 7); post-reperfusion treated with fructose 1-6 diphosphate (n = 7); and post-reperfusion treated with saline (n = 7). Five additional rats were sham operated. Following 30 min occlusion of the superior mesenteric artery, all rats received their respective treatments for 5 days. Post-reperfusion arterial pressure was significantly lower in the control rats (p less than 0.001) as well as when compared with the fructose 1-6 diphosphate groups (p less than 0.001). Significant increase in white blood cell counts occurred in the controls (p less than 0.001), whereas in the fructose 1-6 diphosphate groups white blood cell counts were no different from preischemic values. All control rats that died in less than 5 days had transmural intestinal necrosis, whereas in 3 of the controls that survived 5 days, partial intestinal necrosis was noted. Only one fructose 1-6 diphosphate-treated rat had partial intestinal necrosis. The overall 5-day survival was 100% for sham-operated rats, 93% for fructose 1-6 diphosphate-treated rats, and 21% for controls (fructose 1-6 diphosphate vs. controls, p less than 0.001; fructose 1-6 diphosphate vs. sham, NS). The results are discussed and explained in terms of the postulated mechanism based on the pharmacological properties of fructose 1-6 diphosphate.

Parenteral nutrition of injured patients.

Injured patients treated with fructose 1,6-diphosphate (1 millimole of phosphate per kilogram per day) together with parenteral nutrition had a better nitrogen balance than patients treated with isocaloric nutrition and an inorganic source of phosphate. Excretion of 3-methylhystidine was similar while tyrosine and alanine output from the extremities was lower in the group of patients given fructose 1,6-diphosphate. The data indicates that the protein sparing action of fructose 1,6-diphosphate is exerted through an increased protein synthesis.