Hepatocyte transplants improve liver function and encephalopathy in portacaval shunted rats.

AIM: Rats with portacaval shunt (PCS) are useful experimental models of human hepatic encephalopathy in chronic liver dysfunction. We have previously shown that PCS modifies amine neurotransmitter systems in the CNS and increases voluntary alcohol intake by rats. Hepatocyte transplantation, used in acute liver failure, has recently also been applied to chronic liver diseases, which prompted us to investigate whether the altered brain amine system and the drinking behavior in long-term shunted rats could be normalized by hepatocyte transplants. METHODS: Hepatocytes, isolated from syngeneic donors by collagenase digestion, were injected (3 × 10(6) cells/rat) into the pancreatic tail region, 6 months after PCS. Hepatic function was evaluated by measuring urine urea and plasma L-histidine concentrations. A free choice test with two bottles (tap water and 10% ethyl alcohol) was performed for 3 days to assess the rats' preference for alcohol. The rats were euthanized 2 months posttransplantation. Brain histamine and 5-hydroxyindoleacetic acid (5-HIAA) levels were measured by radioenzymatic assay and by HPLC-EC, respectively, N-tele-methylhistamine by GC/MS while MAOA and MAOB activities by isotopic procedures. RESULTS: Portacaval shunt rats with hepatocyte transplants gave more urea than before transplantation, with lower plasma L-His levels and higher body weight versus the PCS counterparts. Also, those rats consumed less alcohol. The CNS amines and 5-HIAA concentrations, as well as MAO-B activity, being abnormally high in untreated PCS rats, significantly reduced after PCS hepatocyte treatment. CONCLUSIONS: The results support the therapeutic values of hepatocyte transplants in chronic liver diseases and the temporary character of PCS-exerted CNS dysfunctions.

Effects of novel monoamine oxidases and cholinesterases targeting compounds on brain neurotransmitters and behavior in rat model of vascular dementia.

Neurodegenerative disorders are associated with different neurochemical and morphological alterations in the brain leading to cognitive and behavioural impairments. New therapeutic strategies comprise multifunctional drugs. The aim of the presented studies is to evaluate in vivo the novel compounds - ASS188 and ASS234 - which combine the benzylpiperidine moiety of the acetylcholinesteras (AChE) inhibitor donepezil and the indolyl propargylamino moiety of the monoaminooxidase (MAO) inhibitor, N-[(5-benzyloxy-1- methyl-1H-indol-2-yl)methyl]-N-methylprop-2-yn-1-amine, with respect to their influence on cerebral amine neurotransmitters systems and neuroprotective activity. The presumed therapeutic potential of these compounds has been evaluated following their administration to rats with experimental vascular dementia. A rat model of the permanent bilateral occlusion of the common carotid arteries (BCCAO) and the holeboard memory test were employed for this purpose. Wistar rats were used, either intact or 1 day after BCCAO. ASS188 (1 mg/kg) and ASS234 (5 mg/kg) were given s.c. for 5 consecutive days. Working and reference memory in rats was evaluated by holeboard tests before- and 7 and 12 days after BCCAO. The activities of MAOs, AChE and histamine N-methyltransferase (HMT), as well as cerebral amines concentrations were assayed. A significant inhibition of brain MAO A (>95%) and weaker MAO B (ca 60%) and HMT (<30%) and reduced AChE activities were recorded with a pronounced (2 - 10 fold) increase in the cerebral concentrations of serotonin, dopamine, and noradrenaline and smaller rises (up to 30%) of histamine. The BCCAO rats treated with ASS188 or ASS234 tended to perform holeboard tests better than the BCCAO untreated group, indicating a beneficial effect of the administered therapeutics.

Can we use adenosine diphosphate (ADP) to study "aspirin resistance"? The Janus faces of ADP-triggered platelet aggregation.

There is a growing number of contradictory reports indicating that adenosine diphosphate (ADP) can be a useful agonist in monitoring of the antiplatelet action of acetylsalicylic acid (ASA) in humans and animals. In the current study, we aimed to determine the conditions for using ADP to trigger platelet aggregation in order to detect ASA-mediated inhibition of rat platelet reactivity. Initially, we examined the usefulness of different ADP concentrations (0.25, 0.5, 1, 5 and 10 microM) in detecting the in vitro ASA mediated platelet inhibition using whole blood aggregometry, as well as we monitored the role of ADP in generation of thromboxane A(2) (TXA(2)). To study ex vivo ASA inhibitory potential on platelet aggregation induced by a range of ADP concentrations, animals were subjected to one or 10-day ASA administration at the dose of 50 mg/kg. Our experiment shows that ADP in a concentration-dependent manner induces TXA(2) generation in the whole blood with hirudin as an anticoagulant. However, in vitro and ex vivo examination of ASA inhibitory potential on platelet aggregation revealed that irrespectively of administration regimen, ASA failed to block platelet aggregation induced by ADP at the concentrations higher than 0.5 microM. Our findings suggest that the mechanism of ADP-induced platelet aggregation depends on agonist concentration. It appears that only low ADP concentrations (up to 0.5 microM) induce TXA(2)-dependent rat platelet aggregation. Therefore, ADP could be considered a useful platelet agonist for monitoring of ASA-mediated platelet inhibition only if used at much lower concentrations than those commonly employed.

Influence of preischemic short-term triiodothyronine administration on hemodynamic function and metabolism of reperfused isolated rat heart.

BACKGROUND: The "euthyroid sick syndrome" may intensify dysfunction of the heart during acute myocardial ischemia. The present research was undertaken to outline the effects of preischemic short-term triiodothyronine (T3) administration on hemodynamic function and metabolism of the myocardium during reperfusion. MATERIAL/METHODS: Thirty-six isolated working rat hearts were assigned to three experimental groups and a control group. The hearts were removed from the animals and perfused in the modified Langendorff model. They were subjected to 30 minutes of initial perfusion, 40 minutes of ischemia, and 15 minutes of reperfusion. The experimental groups received 10 extra minutes of T3 administration followed by initial perfusion (concentration of T3 was: group 1-5.4 pmol/l, group 2-27 pmol/l, and group 3-54 pmol/l). Control hearts received perfusate without T3. We evaluated the postischemic recovery of left ventricular function (aortic pressures, heart rate, cardiac output), coronary flow, and oxygen consumption. RESULTS: Progressive percentage of recovery of aortic systolic pressure, aortic mean pressure, and cardiac output with increasing concentration of T3 was observed. Cardiac output reached the best recovery in the group with the highest concentration of T3 (80.9+/-7.5%) and was significantly better in comparison with the control group and the other experimental groups. No significant differences in coronary flow and oxygen consumption were noted. CONCLUSIONS: Triiodothyronine administered before ischemia improves postischemic left ventricular function with no changes in oxygen consumption and coronary flow.

Protease inhibitor leupeptin attenuates myocardial stunning in rat heart.

BACKGROUND: In order to test the hypothesis that cardiac protein degradation contributes to the pathogenesis of myocardial stunning, the effect of protease inhibitor leupeptin on the postischemic hemodynamics and metabolic functioning was measured in isolated rat hearts. MATERIAL/METHODS: Isolated rat hearts were perfused in Langendorff mode in the presence or absence of leupeptin (10 Kg/ml for 10 min.), and then subjected to 20 min. of normothermic ischemia and 30 min. of reperfusion. Aortic pressure, cardiac output, coronary flow (CF), global oxygen consumption (MVO2), carbon dioxide and [H+] release, and [Ca2+] uptake were investigated. RESULTS: Hearts pretreated with leupeptin exhibited better postischemic return of systolic, diastolic and developed aortic pressure and faster return of CF to preischemic values during reperfusion. MVO2 and CO2 release were lower in this group in the 10th and 15th min. of reperfusion and [Ca2+] uptake higher in the 5th and 15th min. of reperfusion CONCLUSIONS: Leupeptin protects the heart from myocardial stunning, which is consistent with the idea that proteases contribute to the pathogenesis of this phenomenon.

[L-arginine in reperfusion solution as a heart protecting factor]. / L-arginina w plynie reperfuzyjnym jako czynnik dzialajacy protekcyjnie na miesien serca.

UNLABELLED: Ischemia-reperfusion damage causes injury to both cardiomyocytes and endothelial cells. Loss of endothelium function and degeneration of cardiomyocytes can significantly deteriorate postoperative efficiency of cardiac muscle and in this way can threaten patients' life. The goal of the study was examination how addition of L-arginine to the reperfusion solution influences development of ultrastructural exponents of cardiac muscle injury during reperfusion. MATERIAL AND METHODS: The study was conducted with the use of isolated rat's hearts (Wistar strain), undergoing 20-minute introductory perfusion, 30-minute cardioplegic pause, and then reperfusion conducted on non-working and working heart model, with (study group) and without (control group) the use of L-arginine. RESULTS: Microscopic exponents of injury in cardiomyocytes were most pronounced in the control group. After addition of L-arginine to the reperfusion solution, the decrease in the number of construction points, reduction in overhydration of intra- and extracellular spaces, with diminishing of endothelium vessels' pinocytic activity and decrease in the degree of sarcolemma plication were observed in the study group in comparison with the control group. Increasing of L-arginine doses enhanced slightly its protective activity on the ultrastructure of cardiac muscle. CONCLUSION: Addition of L-arginine to the reperfusion fluid protects cardiomyocytes and endothelium vessels. These positive changes are not recorded in all cardiac muscle specimens.

[The influence of L-arginine on secretion of nitric oxide and haemodynamic function of isolated rat's heart subjected to cold cardioplegic ischemia and reperfusion]. / Wplyw L-argininy na wydzielanie tlenku azotu i funkcje hemodynamiczna izolowanego miesnia sercowego szczura poddanego zimnemu kardioplegicznemu niedokrwieniu i reperfuzji.

BACKGROUND: L-arginine is a precursor of nitric oxide (NO), which is formed endogenously as a result of reaction catalyzed by synthase NO (NOS). Administration of L-arginine to cardioplegic solution St. Thomas Hospital N 2 or used during reperfusion of heart can facilitate the return of left ventricle function after hypothermic ischaemia through increase of release of nitric oxide and preservation of endothelial cells functions. Positive effects of these researches could have extremely beneficial application in clinical practice, improving results of cardiosurgical operations conducted in extracorporeal circulation. OBJECTIVE: How addition of L-arginine to cardioplegic solution or during reperfusion influences secretion of nitric oxide, coronary flow and haemodynamic function of heart. METHODS: The research was conducted on isolated heart model of rats (Wistar inbreeding). The research was carried out in order: 20-minutes initial perfusion, 30-minutes cold cardioplegic arrest with or without addition of L-arginine and reperfusion with Krebs-Henseleit's solution with or without addition of L-arginine. RESULTS: Addition of L-arginine in the preischemic period and during reperfusion stimulates increase of nitric oxide secretion, what positively correlates with increasing of coronary flow. Addition of L-arginine to cardioplegic solution significantly increases coronary flow and cardiac output what improves postischaemic haemodynamic function of heart.

The total antioxidant capacity of blood plasma during cardiovasculary bypass surgery in patients with coronary heart disease.

We studied he effect of ischemia and reperfusion on the total antioxidant capacity (TAC) of blood plasma during cardiopulmonary bypass surgery employing the modified St. Thomas Hospital cardioplegic solution. TAC was determined using the FRAP method. TAC decreased during surgery, but no further decrease in TAC was observed during reperfusion, indicating that it is a relatively stable parameter of the antioxidative barrier of the body.

Effect of L-arginine on overhydration and ultrastructure preservation of rat's heart exposed to cold cardioplegic ischaemia.

UNLABELLED: ISCHAEMIA: Reperfusion damage causes injury both cardiomyocytes and endothelial cells. Loss of endothelium function and heart cells degeneration can be essential for deterioration of postoperative efficiency of heart and in this way can threaten patients' life. OBJECTIVE: How addition of L-arginine to cardioplegic solution influences development of ultrastructural degeneration indications of rat's heart exposed to cold cardiolegic ischemia. METHODS: The research was conducted on isolated heart model of 56 rats, divided into seven equal groups. The hearts were prepared with modified Neely's method and were perfused with the use of apparatus in accordance with modified Langedorf's method. The research was carried out in order: initial perfusion of the non-working and working heart, perfusion with cardioplegic solution, cold cardioplegic arrest with or without addition of L-arginine. RESULTS: In the microscopic preparations of rat's heart in the control group (P) numerous focal performing contraction nodes were found. Intumescent vessels' endothelium included a large number of pinocytal vesicles. In the ultrastructural examination of group DI heart preparations there were less contraction nodes than in control group. The widening of endoplasmatic reticulum's channels and system T was essentially smaller comparing with group P. Less widening of perivascular zone and less number and size of pinocytal vesicles were also observed. In group 2 further decreasing of contraction nodes number was revealed. The structure of capillary was preserved and number of pinocytal vesicles was still decreasing. Further standardization of ultrastructural picture of cardiomyocytes and perivascular zone was found in group 3. CONCLUSION: In control group (P) microscopic degeneration indications of rat's heart were the most intensified. Addition of L-arginine to cardioplegic solution influenced decreasing of intensification of heart degeneration indications. Increasing of L-arginine doses added to cardioplegic solution positive correlates with protective effect of L-arginine on heart ultrastructure.

Effect of L-arginine on oxygen consumption and haemodynamic function of rat's heart exposed to cold cardioplegic ischaemia and reperfusion.

BACKGROUND: Ischaemia--reperfusion damage causes injury of all heart cells. Loss of endothelium function and biologically active substances secreted by it can be essential to development of the damage. Ischaemia and reperfusion decreases the release of nitric oxide, which influences postischaemic coronary flow and return of ventricular function. Administration of L-arginine to cardioplegic and reperfusion solution can improve protection of heart and cause the return of left ventricular function after hypothermic ischaemia through preservation of endothelial cell functions and increase of release of nitric oxide. OBJECTIVE: How addition of L-arginine to cardioplegic solution influences oxygen consumption by myocardium and its postischaemic haemodynamic function. METHODS: The research was conducted on isolated heart model of 56 rats, divided into seven equal groups. The hearts were prepared with modified Neely method and were perfused with the use of apparatus in accordance with modified Langendorf method. The research was carried out in the following order: initial perfusion of the non-working and working heart, perfusion with cardioplegic solution, cold cardioplegic arrest and reperfusion of the non-working heart. RESULTS: During initial perfusion, oxygen consumption was comparable in all groups. During cardioplegic perfusion, oxygen consumption was reduced in every group. At the time of reperfusion of non-working heart model, consumption of oxygen was increased. During reperfusion of the working heart, the lowest oxygen consumption was noted in group P, the highest in group DI. The decrease in cardiac output during postischaemic period was noted in control group and groups where L-arginine was added to reperfusion solution. CONCLUSION: Addition of L-arginine to cardioplegic solution significantly decreases oxygen consumption by myocardium. L-arginine added to cardioplegic solution improves postischaemic haemodynamic function of heart.

Ischemic preconditioning diminishes oxygen demand and increases coronary flow in the early phase of reperfusion in rat heart.

BACKGROUND: Ischemic preconditioning (IPC) can be defined as an adaptive mechanism induced by a brief period of reversible ischemia increasing the heart's resistance to a subsequent longer period of ischemia. The objective of our research was to describe the effects of IPC on the hemodynamic function and metabolism of the myocardium during postischemic reperfusion. MATERIAL/METHODS: 20 rat hearts were assigned to a preconditioning group (n=10) or to a control group (n=10). Preconditioning was achieved with 5 min. of global ischemia and 10 min. of reperfusion followed by 40 min. of ischemia. We investigated the postischemic recovery of aortic pressure, cardiac output, and coronary flow, as well as oxygen consumption, carbon dioxide release, and [H+] release. RESULTS: No significant intergroup differences in aortic pressure and cardiac output were observed during reperfusion. In both groups, increased coronary flow (greater in the IPC group: 11.4+/-0.6 ml/min. vs 9.1+/-0.5 ml/min. in control group) was observed in the early phase of reperfusion. This was accompanied by a rise in CO2 and [H+] release, which was also greater in the IPC group. Oxygen consumption was significantly lower in the IPC group in the later phase of reperfusion (9.39+/-0.53 vs 11.79+/-0.54 micromol/min/g dry weight), as were CO2 and [H+] release. CONCLUSIONS: IPC diminishes oxygen demand during reperfusion without changing the hemodynamic function considerably. IPC results in a transient increase of coronary flow accompanied by a rise in CO2 and [H+] release.