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.

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.

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.

Attenuation of ischemic renal injury with fructose 1,6-diphosphate.

Fructose 1,6-diphosphate (FDP) has been shown to attenuate tissue injury associated with ischemia and shock by enhancing the anaerobic carbohydrate utilization and by inhibiting oxygen-free-radical generation by the neutrophils. Previously, we have reported that FDP prevents ischemic renal failure if administered prior to the ischemic insult. The present study was designed to determine whether this agent could prevent renal damage when administered during the postischemic reperfusion period. Rats were subjected to 30 min of bilateral renal artery occlusion and infused with FDP (350 mg/kg body wt) beginning 10 min after release of the renal artery clamps. Control rats received an equal volume of glucose/saline solution. A third group of rats were sham operated. Twenty-four hours after injury, BUN, creatinine, and fractional sodium excretion values were less in FDP-treated rats than in control rats (P less than 0.001, P less than 0.005, and P less than 0.001, respectively) and not different from values observed in sham-operated rats. Inulin clearance was greater (P less than 0.001) in FDP-treated rats than in control rats (665 +/- 38 microliters/min/g kidney wt). Renal histology was also better preserved in the FDP-treated group. These data suggest that FDP infused after the initiation of an acute ischemic insult provides significant, but not complete, functional and histologic protection from renal damage.

Protective role of fructose 1,6-bisphosphate during CCl4 hepatotoxicity in rats.

Rats were injected intraperitoneally with CCl4 (2.5 ml/kg body wt.) and the hepatotoxicity was compared with that of rats receiving the same dose of CCl4 and an intraperitoneal injection of fructose 1,6-bisphosphate (2 g/kg body wt.). A 50-70% decrease in plasma aspartate aminotransferase and alanine aminotransferase activities was observed in the latter treatment, indicating a protective role of the sugar bisphosphate in CCl4 hepatotoxicity. The protection was accompanied by elevated hepatic activities of ornithine decarboxylase at 2, 6 and 24 h, S-adenosylmethionine decarboxylase at 6 h, and spermidine N1-acetyltransferase at 2 h. The increase in the enzymes involved in polyamine metabolism was shown in our previous work [Rao, Young & Mehendale (1989) J. Biochem. Toxicol. 4, 55-63] to correlate with increased polyamine synthesis or interconversion, which was related to the extent of hepatocellular regeneration. The hepatic contents of fructose 1,6-bisphosphate and ATP significantly decreased after CCl4 treatment, and administration of the sugar bisphosphate increased hepatic ATP. Fructose 1,6-bisphosphate, an intermediary metabolite of the glycolytic pathway, may decrease CCl4 toxicity by increasing the ATP in the hepatocytes. The ATP generated is useful for hepatocellular regeneration and tissue repair, events which enable the liver to overcome CCl4 injury.

[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.

[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.

[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.

Recovery of post-arrest cardiac performance: effect of fructose-1,6-diphosphate in the isolated rabbit heart.

The effect of fructose-1,6-diphosphate (FDP) on the recovery of post-arrest cardiac performance was assessed in isolated rabbit heart preparations subjected to cold ischemic cardioplegic arrest (CICA). Twenty-eight hearts were perfused with Krebs-Henseleit (KHBS) solution followed by 40 minutes of CICA. After CICA normothermic reperfusion with KHBS was restarted. The experimental preparations were divided in four groups of seven hearts each: one group served as control and the other three were perfused with KHBS supplemented with FDP (500 mg/l) given before CICA, after CICA or at both study points. Left ventricular end-diastolic pressure, left ventricular systolic pressure, dP/dt and perfusion pressure were measured at different pre- and post-arrest phases. Time analysis of recovery was also performed. The results demonstrated that FDP supplied prior to and after CICA: prevents the ventricular wall rigidity induced by the ischemic arrest, improves cardiac contractile force both in the basal condition and after cardioplegia, reduces the perfusion pressure, reduces the time to recovery of cardiac contractility. Our findings in the isolated rabbit heart are consistent with published data suggesting FDP may limit the impairment of cardiac dynamics induced by ischemia and improve the recovery after cardiac arrest.

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-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)

Protection from chlordecone (Kepone)-potentiated CCl4 hepatotoxicity in rats by fructose 1,6-diphosphate.

1. The extent of liver injury assessed as elevation of plasma transaminases was decreased 40-50% by administration of fructose 1,6-diphosphate to rats receiving the highly hepatotoxic combination of chlordecone and CCl4. 2. This protection was accompanied by significantly higher sustenance of ATP levels in the liver. 3. Polyamine synthesis as well as interconversion were stimulated in favor of maintaining higher levels of polyamines. 4. These events are consistent with the concept that suppressed hepatocellular regeneration which leads to progression of otherwise limited injury observed in chlordecone potentiation of CCl4 hepatotoxicity is due to lack of cellular energy.

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.

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.

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.

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.