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Query: UMLS:C0022116 (ischemia)
 91,303 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The effect of 48 hours of hypothermic renal ischemia utilizing Euro-Collins flush and short term reperfusion on renal prostaglandin synthesis was studied in dogs. Hypothermic ischemia followed by 60 minutes of reperfusion in-vivo resulted in significant elevations in renal Thromboxane B2 (TXB2) production in the outer cortex, inner cortex, and medulla, relative to non-ischemic kidneys. Prostaglandin E2 (PGE2) and 6-keto Prostaglandin F1 alpha (6-K PGF1 alpha) production were not significantly affected by ischemia and reperfusion. Enhanced TXB2 production was not seen with ischemia alone (without reperfusion) or with reperfusion with O2 saturated buffer, indicating a blood born source or stimuli. Early postreperfusion renal blood flow after hypothermic ischemia followed a biphasic pattern; blood flow increased for the first 10 minutes of reperfusion to achieve normal values, and then steadily declined over the next 20 minutes. This pattern was not altered by the cyclooxygenase inhibitors Idomethacin (5 mg/kg, P.O.) or Mefenamic acid (10 mg/kg, I.V.). Administration of the TXA2 synthesis inhibitor CGS-12970 (3 mg/kg, I.V.) or the TXA2/endoperoxide receptor antagonist SQ-29548 (80 micrograms/min, I.A.) significantly increased renal blood flow during reperfusion but neither agent altered the basic time dependent pattern observed in the control group. These data indicate that 48 hours of hypothermic renal ischemia results in dramatic changes in intrarenal TXA2 synthesis at the time of reperfusion. Enhanced TXA2 production is not dependent on reoxygenation per se, but rather requires reperfusion with blood suggesting a circulatory source.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Prostanoids and hypothermic renal preservation injury. 228 Nov 20

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.
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PMID:Prostaglandin E2 and thromboxane B2 levels in rats subjected to pancreas transplantation. 230 43

The effects of complete ischemia on cerebral arachidonic acid (AA) metabolism were investigated in the isolated perfused rat brain. During 12.5 min of ischemia, AA, 5-hydroxy-6,8,11,14-eicosatetraenoic acid, and 15-hydroxy-5,8,11,13-eicosatetraenoic acid increased 129-, 4-, and 10-fold, respectively, while subsequent reperfusion for 30 min resulted in normalized levels independently of the duration of preceding ischemia. Prostaglandin (PG) F2 alpha, PGE2, PGD2, 6-keto-PGF1 alpha, and thromboxane (Tx) B2 remained at preischemic levels during 12.5 min of complete ischemia. However, at the end of subsequent reperfusion for 30 min, the levels of the prostanoids PGF2 alpha, PGE2, PGD2, 6-keto-PGF1 alpha, and TxB2 increased according to the preceding ischemic time. The levels reached a maximum after 7.5 min of ischemia and were elevated by 7-, 14-, 48-, 3-, and 30-fold, respectively. A prolongation of ischemia of up to 12.5 min was not associated with further increases of prostanoids at the end of reperfusion. The mechanisms underlying the metabolism of eicosanoids are discussed in relation to the changes of cortical direct current potential.
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PMID:Eicosanoids in rat brain during ischemia and reperfusion--correlation to DC depolarization. 232 22

Cardiovascular, platelet- and neutrophil-inhibitory effects of the chemically stable prostacyclin analog nileprost (5-cyano-16-methyl-PGI2) (NIL, ZK 34798) were studied in vitro and in a feline model of acute myocardial ischemia in vivo. Isolated bovine coronary arteries were relaxed by NIL at low concentrations (less than 3 microM), whereas higher concentrations produced a marked vasoconstriction. NIL inhibited human platelet aggregation and reduced the coronary vascular resistance of Langendorff-perfused rabbit hearts. Myocardial contractile force and oxygen consumption were not affected. The superoxide anion generation of stimulated granulocytes was modestly antagonized by NIL. NIL (0.5 microgram/kg/min intravenously, i.v.) protected the left ventricular myocardium of cats subjected to 5 h of coronary artery ligation from ischemic injury, as evidenced by the reduction in ischemia-induced ST-segment elevation, prevention of the large increase in plasma creatinine kinase (CK), and loss of myocardial CK and free amino nitrogen. These effects and the extent of cardiac protection by NIL were comparable to those of PGI2 (0.2 microgram/kg/min), whereas PGE2 (1.5 microgram/kg/min) was less effective. The data demonstrate a combination of PGI2-like and PGE2-like activities for NIL in vitro and a significant cardioprotective action of NIL in vivo.
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PMID:Cardiovascular actions in vitro and cardioprotective effects in vivo of nileprost, a mixed type PGI2/PGE2 agonist. 244 Nov 64

Myocardial ischemia was induced in perfused paced isovolumic left heart preparation of the rabbit by reducing, for a period of 40 min, the flow rate from 20 ml/min to 0.2 ml/min (severe model) and to 1 ml/min (moderate model). The relationship between prostaglandin biosynthesis and cardiac ischemic damage was evaluated in the two experimental models. The results obtained indicate that the total amount of 6-keto-PGF1 alpha generated increases with the severity of the ischemia, particularly during the 20 min of reperfusion (moderate model 81.8 +/- 13.7 ng: severe model 375 +/- 102 ng). The inhibition of the prostaglandin synthesis, prostaglandin-E2, and 6-keto-prostaglandin-F1 alpha (PGE2 and 6-keto-PGF1 alpha levels below the detection limits) by Aspirin (20 micrograms/ml) and Indomethacin (1 microgram/ml) in moderate myocardial ischemia was correlated with greater increments in resting diastolic tension (nearly 100% and 40%, respectively). This phenomenon was also associated to a further decrease on cardiac contractility and increase on coronary perfusion pressure upon reperfusion. On the contrary drugs which stimulated prostaglandin generation in myocardial tissue, such as Defibrotide (400 micrograms/ml), completely protected the organ from ischemia. U-60257 (3 micrograms/ml) and FPL-55712 (2 micrograms/ml), compounds, which respectively inhibits biosynthesis and the effects of leukotrienes, displayed a beneficial activity on this moderate model of ischemia. The present data suggests that the deleterious effect of nonsteroidal antiinflammatory drugs in low flow myocardial ischemia and reperfusion damage may be associated with removal of PGI2 and PGE2 from ischemic myocardium.
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PMID:Nonsteroidal antiinflammatory drugs aggravate acute myocardial ischemia in the perfused rabbit heart: a role for prostacyclin. 246 44

The mechanisms whereby diet-induced alterations in fatty acids may affect renal structure and function are unknown. Kidneys from rats fed chow supplemented with 18% (wt/wt) coconut oil (CO, n = 8), sunflower seed oil (SO, n = 7), or fish oil (FO, n = 8) were isolated from systemic influences of the diets and perfused with a cell-free medium. The FO diet caused a twofold reduction in prostaglandin (PG) I2 (urine excretion of 6-keto-PGF1 alpha) compared with SO and CO. Urine PGE2 and thromboxane (Tx) B2 were similar in the three diet groups. There was a 22% reduction in perfusate flow associated with the decrease in PGI2 in the FO group (42 +/- 6 ml.min-1.g-1) compared with the CO (54 +/- 7 ml.min-1.g-1) and SO (54 +/- 8 ml.min-1.g-1) groups (mean +/- SD, P less than 0.05). The glomerular filtration rate (GFR) was similar in the three groups during the initial base-line determination but subsequently declined to a greater degree in the FO group. Morphologically, tubular injury was most extensive in the FO group, and the distribution of the injury indicated that it was caused, at least in part, by ischemia. The decline in GFR and the degree of histological injury were more closely linked to the diminished PGI2 production. Thus dietary FO supplementation caused decreased renal PGI2, increased renal vascular resistance, and an increased susceptibility to ischemic tubular cell injury in the isolated kidney.
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PMID:Fish oil diet decreases prostacyclin and increases resistance in isolated rat kidneys. 265 78

This paper summarizes what has been learned over the years about the role of eicosanoids in the pathogenesis of primary dysmenorrhea, endometriosis and menstrual migraine. The role of prostaglandins (PGs) in the pathogenesis of primary dysmenorrhea is inferred from four main observations: firstly, the clinical symptoms of primary dysmenorrhea are similar to those induced by the administration of PGF2 alpha and PGE2 for the induction of labour; secondly, the increased production of PGs by the endometrium during the luteal and menstrual phases of ovulatory cycles is consistent with the occurrence of primary dysmenorrhea mainly in ovulatory cycles; thirdly, the concentrations of PGF2 alpha and PGE2 in the endometrium and menstrual fluid of dysmenorrheic women are significantly higher than in controls; fourthly, certain PG inhibitors have been proved to be effective in the treatment of dysmenorrhea. The change in PG production can explain the major symptoms of primary dysmenorrhea, including the increased uterine contractility, uterine ischemia and the lowering of the pain threshold to chemical and physical stimuli in the pelvic nerve terminals. Moreover, recent experimental data suggest that leukotrienes (LTs) might be among the alternative pathogenetic causes of primary dysmenorrhea. The data which support a relationship between eicosanoids and endometriosis are as follows: endometriotic tissue produces PGs; the peritoneal fluid concentration of PGF2 alpha increases significantly after the induction of endometriosis in laboratory animals; the concentration of PGs in peritoneal fluid of some patients with endometriosis is greater than in controls and, finally, the number and activation of pelvic macrophages which are able to synthesize eicosanoids increase in patients with endometriosis. Possible roles for eicosanoids in the pathogenesis of infertility and secondary dysmenorrhea induced by endometriosis have been suggested. Eicosanoids are probably also involved in the pathogenesis of menstrual migraine. Different types of PGs might play a role both in the initial vasoconstriction during the prodromal phase of migraine and in the vasodilation and sensitization to pain typical of the pain phase.
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PMID:Eicosanoids in primary dysmenorrhea, endometriosis and menstrual migraine. 265 74

Eighteen patients suffering from true menstrual migraine and 12 control subjects were studied. We evaluated in different phases of the menstrual cycle and during the migraine crisis the peripheral plasma concentrations of 6-keto-PGF1 alpha (the stable metabolite of PGI2), thromboxane B2 (the stable metabolite of thromboxane A2), PGF2 alpha and PGE2. The mean values of 6-keto-PGF1 alpha in menstrual migraine sufferers are lower than in normal women throughout the whole cycle. The difference between the trends observed in the two groups is statistically significant (p less than 0.05). The plasma levels of TXB2 and of PGF2 alpha are similar in the two groups investigated, both in basal conditions and during the attack. The plasma concentrations of PGE2 are slightly lower in migraineurs in basal conditions than in normals. However, during the crisis they increase significantly (p less than 0.05). In conclusion, among all the parameters considered, PGE2 seems to play the most important role during the pain phase of the attack. The results of the present study suggest that a deficit of PGI2, one of the most important protecting agents against ischemia, might be a typical feature of menstrual migraine and might cause in these patients a vascular hypersensitivity to different ischemic stimuli.
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PMID:Relevance of prostaglandins in true menstrual migraine. 271 74

We explored the temporal and topographic relations between local cerebral blood flow and regional brain prostaglandin profile following prolonged or transient occlusion of the middle cerebral artery in cats. Each experimental group was subjected to a sham operation, prolonged ischemia, or recirculation. Local cerebral blood flow was measured by the hydrogen clearance method. Following in situ freezing, cortical samples were obtained from each gyrus for determination of prostaglandin (PG) F2 alpha, PGE2, 6-keto-PGF1 alpha, and thromboxane (TX) B2 concentrations by radioimmunoassay. During prolonged ischemia, the concentrations of PGF2 alpha and PGE2 within the middle cerebral artery territory were significantly increased. Immediately after recirculation, there was a prominent but transient increase in PGF2 alpha and PGE2 in gyri that had been exposed to moderate ischemia (perifocal area). By contrast, the increases in these prostaglandins were slow and less prominent in gyri that had been exposed to severe ischemia (the focal area). The concentration of 6-keto-PGF1 alpha did not change during prolonged ischemia but transiently increased following recirculation in both the focal and perifocal areas. The TXB2 concentration did not change in any experimental group. Our study revealed a homogeneous increase in the regional brain content of PGE2 or PGF2 alpha in spite of the heterogeneous reduction of local cerebral blood flow during prolonged ischemia. Following recirculation, the focal and perifocal areas exhibited different patterns of prostanoid content. No correlation was found between local cerebral blood flow and the regional concentration of any prostaglandin examined.
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PMID:Prostaglandin profiles in relation to local circulatory changes following focal cerebral ischemia in cats. 272 49

The effects of cerebral ischemia on cerebral microvascular reactivity and prostanoid synthesis were examined in chloralose-anesthetized newborn pigs. Microvascular responses and periarachnoid cerebrospinal fluid (CSF) prostanoid concentrations were determined between 10 and 140 min after a 20-min period of total cerebral ischemia, as well as in sham-control piglets without cerebral ischemia. After cerebral ischemia, the decrease in pial arteriolar diameter in response to topical norepinephrine (10(-4) M) was similar in sham (-27 +/- 6%) and postischemic (-25 +/- 5%) piglets. However, the increase in pial arteriolar diameter in response to hypercapnia (10% CO2 ventilation) that was observed in sham piglets (+21 +/- 5%) was absent after ischemia (-2 +/- 3%). In contrast, dilations of pial arterioles in response to topical prostaglandin (PG)E2 (at 100 ng PGE2/ml: sham, +13 +/- 3%; postischemia, +21 +/- 4%) and topical isoproterenol (10(-6) M) (sham, +29 +/- 4%; postischemia, +23 +/- 3%) were not decreased by prior cerebral ischemia. In sham piglets, norepinephrine and hypercapnia produced increases in cortical periarachnoid prostanoid concentrations, whereas after cerebral ischemia, neither stimulus increased cortical periarachnoid prostanoid concentrations. The results are consistent with the hypothesis that failure of hypercapnia to dilate pial arterioles after cerebral ischemia results from the inability of this stimulus to increase cerebral vasodilator prostanoid synthesis.
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PMID:Cerebral ischemia alters cerebral microvascular reactivity in newborn pigs. 275 Sep 42


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