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F Pi

Publications and source records attributed to F Pi.

30 records · Page 2Linked to original sources
PubMed1994

Arachidonate metabolism in ischemia-reperfusion associated with pancreas transplantation.

The implication of eicosanoid metabolism and its relationship with oxygen free radical production in the process of ischemia-reperfusion associated with rat pancreas transplantation has been explored in this study. For this purpose male Sprague-Dawley rats were classified as follows: group I, control animals not surgically manipulated; group II, pancreas transplantation, after 30 min preservation in UW solution; group III, pancreas transplantation after 12 h preservation under the same conditions; group IV, same as group III but with administration of SOD 5 min prior to organ revascularization. The results show post-transplantation increases in 6-keto-PGF1 alpha, TXB2, LTB4 and 12-HETE in pancreatic tissue independent of preservation time. The fact that SOD administration could reverse these increases even though an efficient xanthine oxidase irreversible inhibitor such as allopurinol was present in the preservation solution suggests that eicosanoid generation in the recipient rat would be mediated by an oxygen free radical dependent mechanism not exclusively dependent on endothelial xanthine oxidase activity.

12-Hydroxy-5,8,10,14-eicosatetraenoic Acid↗
PubMed1992

Alpha 2-autoreceptor-mediated modulation of tyrosine hydroxylase activity in noradrenergic regions of the rat brain in vivo.

The physiological importance of brain alpha 2-adrenoceptors in controlling the activity of tyrosine hydroxylase in noradrenergic regions was investigated using the accumulation of 3,4-dihydroxyphenylalanine (DOPA) after decarboxylase inhibition as a measure of the rate of tyrosine hydroxylation (and synthesis of noradrenaline) in vivo. In the hypothalamus and cerebral cortex, clonidine (0.025-1 mg/kg, i.p.) decreased (18%-43%) and idazoxan (0.1-80 mg/kg, i.p.) increased (20%-73%) the synthesis of DOPA in a dose-dependent manner. Moreover, pretreatment with idazoxan (0.1 mg/kg) antagonized the effect of clonidine (0.1 mg/kg) in the hypothalamus. After treatment with reserpine (5 mg/kg, s.c., 18 h before decapitation) and depletion of noradrenaline, clonidine (0.5 mg/kg) continued to decrease (50%-55%) but idazoxan (20 mg/kg) failed to increase the synthesis of DOPA, which suggested the involvement of an alpha-auto-receptor mechanism. Acute treatments of rats (not exposed to reserpine) with a wide variety of adrenoceptor agonists such as guanfacine 6, B-HT920, xylazine, bromoxidine (1 mg/kg) and antagonists such as yohimbine, phentolamine, prazosin (10 or 20 mg/kg) resulted in significant decreases (15%-55%) or increases (21%-99%) in the synthesis of DOPA in both brain regions. However, other agonists (oxymetazoline, azepexole, tramazoline, methoxamine) and antagonists (tolazoline, dihydroergotamine, phenoxybenzamine, propranolol) did not modify the synthesis of DOPA. In the hypothalamus and cerebral cortex the effects of the drugs were consistent with the selectivity of alpha-adrenoceptor agonists and antagonists (except prazosin) for an alpha 2-adrenoceptor. The results also suggest that the alpha 2-autoreceptor that modulates the synthesis of noradrenaline in the rat brain appears to belong to the prazosin-sensitive alpha 2B-subtype.

Adrenergic alpha-Antagonists↗
PubMed1991

Altered levels of tissue and urinary prostacyclin in rats subjected to pancreas transplantation.

Significant increases of TXB2 and PGE2 are reported to occur in pancreas transplantation. These increases are prevented with scavengers of oxygen-free radicals. In this communication, we report on changes of prostacyclin metabolites such as tissue 6-keto prostaglandin F1 alpha and urinary 2,3-dinor 6-keto prostaglandin F1 alpha in rats subjected to pancreas transplantation after different periods of organ cold preservation ischemia as well as the effect of superoxide dismutase (SOD) on these changes. For this purpose, male Lewis rats were classified as follows: Group I, Control; Group II, syngenic pancreas transplantation after 15 min of organ preservation in Collins solution at 4 degrees C; Group III, same as II but with 12 hours of organ preservation; Group IV, same as III, but with SOD pretreatment. Results have shown significant posttransplantation increases of both tissue 6-keto PGF1 alpha and urinary 2, 3 dinor 6-keto PGF1 alpha, the latter being a useful marker to evaluate systemic prostacyclin (PGI2) production by rat pancreas. This effect was prevented when the organ had been exposed to SOD during the period of cold preservation ischemia. These results confirm the implication of oxygen-free radicals (OFR) in the ischemia-reperfusion process associated to rat pancreas transplantation leading to enhanced arachidonic acid metabolism.

6-Ketoprostaglandin F1 alpha↗
PubMed1990

Prostaglandin E2 and thromboxane B2 levels in rats subjected to pancreas transplantation.

This work undertakes the study of changes in urinary, plasmatic and tissue levels of Thromboxane B2 (TXB2) as well as in tissue Prostaglandin E2 (PGE2) after pancreas transplantation and the effect of superoxide dismutase (SOD) on these changes. For this purpose, streptozotocine induced diabetic rats were subjected to pancreas transplantation. Experimental groups were classified as follows: Group I: Control; Group II: Animals subjected to 15 min of pancreas arterial flow occlusion followed by reperfusion; Group III: Syngenic pancreas transplantation after 12 hours of organ preservation; Group IV: Same as III, but with additional SOD (13 mg/kg) pretreatment. The results indicate that significant increases of PGE2 and TXB2 levels occur as a consequence of the surgical removal, preservation and implantation of the organ. For TXB2 these increases, immediate in plasma and tissue, are not detected in urine until 24 hours after transplantation of the pancreas. The release of TXB2 and PGE2 was effectively prevented in the SOD treated group supporting the role of oxygen free radicals and lipid peroxidation in the processes of ischemia-reperfusion associated to transplantation of the pancreas.

Animals↗
PubMed1986

Presence of a noradrenaline uptake system on a ligated cat sympathetic nerve.

[3H]noradrenaline [( 3H]NA) uptake studies were carried out in cat hypogastric nerves ligated in vivo, 2 cm distal to the inferior mesenteric ganglion, for different time periods. Atria from the same animals served as controls to determine the uptake of the amine by the U1 uptake system present in noradrenergic nerve terminals. The net uptake of [3H]NA by hypogastric nerves increased with time of ligation, reaching a maximum 24 h after ligation in the segment of nerve immediately proximal to the ligature (P1 segment, neurosome). No further increase in uptake was observed at 48 or 72 h. Segments distal (D1) to the ligature also retained significant amounts of [3H]NA. In both cases the uptake was blocked by cocaine (3 microM). Reserpine pre-treatment (2 mg/kg I.M.) markedly decreased the endogenous NA content to 1-2% of untreated cats and the net uptake of [3H]NA was lowered to 25% both in cat hypogastric nerve and atria. The uptake was further decreased in the presence of cocaine (3 microM). 6-Hydroxydopamine (100 microM) did not modify the [3H]NA uptake by ligated cat hypogastric nerves but almost abolished the [3H]NA net uptake by right atria from the same animals. After collagenase pre-treatment (0.05% for 15 min) the net uptake of [3H]NA was not altered in the atrium. However, collagenase-pre-treated ligated nerves, took up almost twice as much [3H]NA; under these conditions, 6-hydroxydopamine produced a marked decrease in [3H]NA net uptake. These data suggest the presence in the perineurium of a diffusion barrier for very polar substances, including 6-hydroxydopamine. In conclusion, our data demonstrate that the cat hypogastric nerve ligated in vivo has a cocaine-sensitive system for NA uptake which resembles the NA uptake mechanism (U1) present in noradrenergic nerve terminals. Our data further support the view that the ligated cat hypogastric nerve (neurosome) could be considered as a model of noradrenergic nerve terminal free of effector cell.

Animals↗
PubMedDate not supplied

Postoperative hypocaloric parenteral nutrition. A study in patients without neoplasm.

Hypocaloric peripheral parenteral nutrition during the postoperative period aims to reduce or minimize protein loss and avoid use of central venous catheters. The efficacy of such nutrition in regard to postoperative outcome and nitrogen balance was evaluated in comparison with standard fluid therapy. The study was performed on 49 well-nourished patients who underwent major surgery for non-neoplastic conditions. Group I received 1 g amino acids + 1 g xylitol and 1 g sorbitol/kg body weight, while standard fluid therapy was given in group II. No significant intergroup difference was found in serum levels of albumin, total protein, prealbumin, transferrin or retinol-binding protein. The blood urea, nitrogen excretion and nitrogen balance were significantly higher in group I. The postoperative outcome was similar in both groups, as were the observed complications. Thus although the nitrogen balance was superior in group I, no intergroup difference was clinically evident.

Abdomen↗