Placental thromboxane and prostacyclin in the regulation of placental blood flow

To study the significance of placental thromboxane A2 and prostacyclin in the regulation of placental blood flow, intervillous blood flow was measured using a 133Xenon method from 39 women zero to two days before delivery and compared it with the placental production of thromboxane A2 and prostacyclin as measured with a superfusion method postpartum. The placental production of thromboxane B2 (a metabolite of thromboxane A2; 4.5 +/- 1.3 ng/minute per gram dry weight of tissue; mean +/- SD) and that of 6-keto-prostaglandin F1 alpha (a metabolite of prostacyclin; 0.64 +/- 0.27 ng/minute per gram) did not correlate significantly with intervillous blood flow (153.1 +/- 108.0 mL/minute per 100 mL; r = -0.308 and 0.245, respectively), whereas the thromboxane B2/6-keto-prostaglandin F1 alpha ratio (8.53 +/- 4.3) was inversely related to intervillous blood flow (r = -0.419; P less than .01). In the women with intervillous blood flow below the normal mean (less than 130 mL/minute per 100 mL; N = 20) placental thromboxane B2 production (5.1 + 1.2 ng/minute per gram) was higher (P less than .005) and that of 6-keto-prostaglandin F1 alpha (0.54 +/- 0.23 ng/minute per gram) lower (P less than .02) than those in women with intervillous blood flow above 130 mL/minute per 100 mL (thromboxane B2 4.01 +/- 1.0 and 6-keto-prostaglandin F1 alpha 0.75 +/- 0.27 ng/minute per gram; N = 19). These results suggest that placental thromboxane A2 and prostacyclin may be factors in the regulation of intervillous blood flow and that their balance of production is more important than the presence of either agent alone.(ABSTRACT TRUNCATED AT 250 WORDS)

An ultrasensitive time-resolved immunofluorometric assay of human epidermal growth factor

We have developed a sandwich-type time-resolved immunofluorometric assay (TR-IFMA) for human epidermal growth factor (hEGF) in body fluids. A two-step solid-phase technique was used. The assay utilizes a polyclonal anti-hEGF attached to the solid phase, and a monoclonal anti-hEGF labeled with Europium (III) as a tracer. The sensitivity of the assay (2.5 pg/ml) is at least 20 times better than what has been achieved by radioimmunoassay (RIA), and the measuring range is much wider: 2.5-5000 pg/ml. The feasibility of TR-IFMA was tested by assaying urine containing large amounts and amniotic fluid containing small amounts (mostly undetectable by RIA) of immunoreactive hEGF. The correlation between urine hEGF concentrations (1-100 ng/ml) measured by RIA and TR-IFMA was good: r = 0.96.

Vaginal and abdominal delivery increases maternal urinary 6-keto-prostaglandin F1 alpha excretion

To study the role of the antiaggregatory and vasodilatory prostacyclin (PGI2) during human delivery, serial urine samples collected from 13 women delivered vaginally and from eight delivered abdominally were assayed for 6-keto-prostaglandin F1 alpha (6-keto-PGF1 alpha, a breakdown product of PGI2) by high-performance-liquid-chromatography and radioimmunoassay. In women delivered vaginally the mean urinary 6-keto-PGF1 alpha concentration was 41.9 (SE 8.3) ng/mmol creatinine, before the onset of labour and increased progressively to a maximum of 186.5 (SE 47.6) ng/mmol creatinine 2 h after delivery irrespective of the use of oxytocin and epidural analgesia. In women delivered by caesarean section under epidural anaesthesia, the urinary 6-keto-PGF1 alpha rose from 33.4 (SE 4.2) ng/mmol creatinine to 2153 (SE 314) ng/mmol creatinine 2 h after section. In both groups the increased levels had fallen by 24 h postpartum to levels below those found before delivery. In neonatal urine 6-keto-PGF1 alpha concentrations were some 12-30 times higher than those in postpartum urine. Thus, vaginal and abdominal delivery is accompanied by significant increases in maternal PGI2 release, perhaps in the myometrium and/or intrauterine tissues. This may be of significance in the regulation of fetoplacental blood flow and in the prevention of intra- and postpartum thrombosis.

Platelet function and coagulation in normal and preeclamptic pregnancy

Platelet function and coagulation activity were followed prospectively throughout normal pregnancy and in puerperium in 17 healthy women. Plasma beta-thromboglobulin reflecting platelet activation increased progressively during pregnancy. This was not accompanied by any changes in platelet count or lifespan nor in serum or plasma thromboxane B2 levels. The levels of both factor VIII:C and factor VIIIR:Ag increased, the former less than the latter resulting in a rise of the FVIIIR:Ag/FVIII:C ratio. Antithrombin III (AT III), however remained unaltered. FVIIIR:Ag/FVIII:C ratio was increased both in mild (n = 7) and severe (n = 9) preeclampsia, whereas beta-thromboglobulin was increased and AT III was decreased only in severe preeclampsia. Platelet count and lifespan, plasma and serum thromboxane B2 as well as FVIII:C were normal in severe preeclampsia.

Maternal ingestion of acetylsalicylic acid inhibits fetal and neonatal prostacyclin and thromboxane in humans

Small doses of maternal acetylsalicylic acid have proved to prevent preeclampsia. To study the mechanism of this action of acetylsalicylic acid, healthy women ingested 100 mg (n = 13) or 500 mg (n = 14) of acetylsalicylic acid during labor at term. The fetal prostacyclin synthesis, as assessed by the production of 6-ketoprostaglandin F1 alpha (a metabolite of prostacyclin) by the umbilical artery, was reduced from 21.3 +/- 1.6 ng/gm/min of dry weight in the controls (n = 25, mean +/- SE) to 7.8 +/- 1.1 ng/ml/min (p less than 0.001) in infants of mothers receiving 500 mg of acetylsalicylic acid, but it was unchanged in infants with mothers receiving 100 mg of acetylsalicylic acid (19.5 +/- 2.3 ng/gm/min). Maternal ingestion of 500 mg of acetylsalicylic acid also was accompanied by reduced (p less than 0.10) urinary excretion of 6-ketoprostaglandin F1 alpha in neonates during the first 3 days of life. The fetal platelet thromboxane A2 synthesis, as assessed by the release of thromboxane B2 (a metabolite of thromboxane A2) during spontaneous clotting of the umbilical blood (63.4 +/- 4.2 pg/10(5) platelets, n = 22), was inhibited in infants born to mothers given 100 mg (14.0 +/- 3.7 pg/10(5) platelets, p less than 0.001) or 500 mg of acetylsalicylic acid (6.1 +/- 3.5 pg/10(5) platelets, p less than 0.001). The thromboxane B2 release by the umbilical artery (1.1 +/- 0.1 ng/gm/min, n = 13) also was decreased in infants of mothers receiving 500 mg of acetylsalicylic acid (0.57 +/- 0.1 ng/gm/min, n = 7, p less than 0.01). Thus a small dose of maternal acetylsalicylic acid (100 mg) inhibits only the fetoplacental thromboxane A2 but leaves prostacyclin production unaffected.

Dietary fatty acids and platelet thromboxane production in puerperal women and their offspring

The effects of the ratio of polyunsaturated to saturated fatty acids in the diet of puerperal women on maternal and neonatal fatty acids and thromboxane A2 synthesis were studied in 91 mother-infant pairs on the fourth to fifth day after delivery. The mothers received a diet with either a low (0.1) or a high (1.5) polyunsaturated to saturated fatty acid ratio for 4 to 5 days. The fatty acid composition in maternal and neonatal serum and in breast milk was determined in 34 mother-infant pairs from both dietary groups. The capacity of the platelets to produce thromboxane B2, a stable metabolite of thromboxane A2, was determined in another 57 mother-infant pairs. The percentage of linoleic acid was increased in maternal and neonatal sera as well as in the breast milk in the group with a high dietary polyunsaturated to saturated fatty acid ratio, whereas the content of arachidonic acid was increased only in maternal serum. This was accompanied by increased platelet thromboxane B2 production in the mothers, and maternal and neonatal thromboxane B2 synthesis correlated significantly with each other (r = 0.43, p less than 0.05). This finding may provide therapeutic possibilities in the future.

Subnormal concentrations of urinary epidermal growth factor in patients with kidney disease

We determined the concentrations of immunoreactive epidermal growth factor (irEGF) and creatinine in urine samples from 47 adult patients with various kidney diseases and wide ranges of azotemia and proteinuria. In most of the patients, urinary irEGF concentrations (nanograms per mg creatinine) were markedly subnormal. In the entire group, urinary irEGF correlated with creatinine clearance (r = 0.79; P less than 0.001) and serum creatinine concentration (r = -0.85; P less than 0.001). In the subgroups of patients with primarily glomerular or tubulointerstitial diseases, similar correlations were found. By contrast, there was no correlation with proteinuria. We also determined the concentrations of plasma irEGF in five patients with azotemia. In four patients, the irEGF to creatinine concentration ratio was 1.9- to 8.9-fold higher in urine than in plasma, indicating that plasma irEGF was not the main source of urinary irEGF in these patients. Our data are compatible with the theory that urinary irEGF originates from nephrons per se.

Increased platelet thromboxane B2 production in newborn infants of diabetic mothers

Platelet thromboxane B2 (TxB2) production, plasma concentrations of C-peptide and pancreatic glucagon as well as blood glucose levels were measured in 12 infants of insulin-dependent diabetic mothers and eight healthy controls at the age of two hours. Platelet TxB2 production (p less than 0.05) and plasma C-peptide levels (p less than 0.02) were significantly higher and blood glucose concentrations lower (p less than 0.002) in the infants of the diabetic mothers than in the controls. The data suggest that platelets of infants of diabetic mothers produce increased amounts of proaggregatory thromboxane A2, which may contribute to the hyperaggregation in these infants.

Dermal prostacyclin, thromboxane A2 and prostaglandin F2 alpha in climacteric women: effect of oestrogen replacement therapy

The involvement of dermal prostanoids in menopausal flushing was studied in 8 women suffering from climacteric hot flushes and in 10 asymptomatic control subjects by inducing suction blisters on abdominal skin and assaying blister fluids for 6-keto-PGF1 alpha, a metabolite of the vasodilative prostacyclin (PGI2), thromboxane B2 (TxB2), a metabolite of the vasoconstrictive thromboxane A2 (TxA2), and 13,14-dihydro-15-keto-PGF2 alpha (M-PGF2 alpha), a metabolite of prostaglandin F2A (PGF2A). No marked differences were observed in the levels of these prostanoids in the two study groups. The women experiencing flushes then received conjugated oestrogens for 3 mth to abolish vascular instabilities. This decreased the blister fluid concentration of M-PGF2 alpha from 1720 +/- 476 pg/ml (mean +/- SE) to 1490 +/- pg/ml (P less than 0.05), but had no effect on the dermal levels of 6-keto-PGF1 alpha or TxB2. It was concluded that although certain dermal prostanoids may be affected by oestrogen treatment they are not of primary significance as regards menopausal flushing.

Effects of smoking and nicotine on human prostacyclin and thromboxane production in vivo and in vitro

We studied the effects of smoking and nicotine on the production of proaggregatory thromboxane A2 (TxA2), antiaggregatory prostacyclin (epoprostenol, PGI2), and on lipid peroxidation in vivo and in vitro. In the in vivo study, serum concentrations of thromboxane B2 (TxB2), a stable metabolite of TxA2, increased immediately after smoking three cigarettes but not after smoking the equivalent amount of tobacco in a pipe, whereas serum lipid peroxide values did not change in either group. In vitro, nicotine (2 X 10(-3) mol/liter) inhibited pulmonary TxB2 production by 70% and simultaneously stimulated the production of 6-keto-prostaglandin F1 alpha, a stable metabolite of PGI2, by 40%, which suggest that nicotine does not exert its effect at the cyclooxygenase level. During aggregation in platelet-rich plasma, TxB2 production was inhibited by 53% with 2 X 10(-3) mol/liter of nicotine, and during whole blood clotting the inhibition was 34% with 2 X 10(-4) mol/liter of nicotine. Thus the rise in cigarette smokers' serum TxB2 was probably caused by some constituent of cigarette smoke other than nicotine. The increased production of TxA2 following cigarette smoking may provide one explanation for the increased incidence of atherosclerosis and its complications in cigarette smokers.

Dynamic evaluation of prolactin secretion by successive TRH and metoclopramide stimulations

We evaluated the clinical applicability of a 2-h test in which the prolactin (Prl) responses to thyrotrophin releasing hormone (TRH)(200 micrograms iv) and the dopamine antagonist, metoclopramide (MC; 10 mg iv) were studied successively, 1 h apart. Nine healthy women were studied with TRH-MC test and with another test in which MC alone was used or the drugs were given in opposite order. The preceding TRH injection did not affect the Prl responses to MC, nor did preceding MC affect the Prl response to TRH. With the TRH-MC test, Prl responses to TRH and MC were significantly lowered in amenorrhoea (N = 8) and hyperprolactinaemia (N = 15) regardless of whether or not treated with bromocriptine, and to MC only in oligomenorrhoea (n = 11). In normoprolactinaemic galactorrhoea (N = 7) the responses were similar as in healthy women. The ratio between Prl responses to TRH and MC was significantly higher in women with bromocriptine-treated hyperprolactinaemia (1.06 +/- 0.8, SD) than in healthy controls (0.34 +/- 0.13). The capacity of pituitary lactotrophs to secrete Prl in response TRH and MC can be evaluated with a 2-h test which has potential for investigation of pituitary Prl dynamics in gynaecological endocrine disorders, particularly in amenorrhoea and hyperprolactinaemia.

Urinary neopterin index as a measure of rheumatoid activity

The urinary neopterin index (U-NEOPT-I), expressed as micro-moles of neopterin/moles of creatinine) of 67 patients with definite or classical rheumatoid arthritis was significantly higher than that of sex- and age-matched persons or of 24 non-matched patients suffering from osteoarthrosis or arthralgia (2p less than 0.001). Furthermore, the patients with active disease had statistically significantly increased U-NEOPT-I when compared with patients with a clinically less active disease. In this study, the U-NEOPT-I value was the equal of CRP as a measure of rheumatoid activity. We suggest that neopterin might be involved in the pathogenesis of rheumatoid arthritis.

Platelet function and thrombus in diabetes

Patients with diabetes mellitus are several fold more prone to various forms of vascular diseases than are the non-diabetic subjects. Because platelets are in the key position in thrombus formation and possibly in atherogenesis, much interest has focused on the role of platelets in the development of diabetic vascular disease. Most studies on this topic have suggested increased adhesiveness and aggregability of the platelets from diabetic patients. The increased production of von Willebrand factor may account for the enhanced adhesion. The shift of the balance between proaggregatory thromboxane A2 and antiaggregatory prostacyclin to the dominance of thromboxane A2 could explain the increased aggregability of diabetic platelets, but the data available at the moment do not allow the conclusion that such a change really exist in human in vivo. One recent work has suggested that the increased glycosylation of connective tissue proteins in diabetes would increase their aggregating potency, but also this finding needs further confirmation.

Epidermal growth factor in human urine from birth to puberty

The highest concentrations of epidermal growth factor (EGF) are found in urine, but the physiological role of urinary EGF is unknown. We studied human urinary EGF excretion, by measuring its concentration with a specific homologous RIA, in 265 healthy children from birth until age 16 yr. The absolute concentrations varied widely between individuals. Mean values were approximately 10 ng/ml in 1- to 30-day-old infants; 2.5-fold higher values were found in infants aged 2 to 12 months. During the second year there was a further rise to about 70 ng/ml, and urinary EGF excretion was in the same range in older subjects. The EGF/creatinine concentration ratio was less variable. The mean ratio increased 6-fold from birth to the second year of life. Thereafter, the EGF/creatinine ratio decreased gradually to one-third of the peak level at puberty. No sex difference was found.

Effect of nicotine on fetal prostacyclin and thromboxane in humans

To study the effect of nicotine on fetal prostacyclin and thromboxane A2, specimens from the umbilical arteries of infants born to healthy nonsmoking mothers were superfused in the absence or presence of nicotine (50 to 10,000 micrograms/mL), and the releases of 6-keto-prostaglandin F1alpha (a break-down product of prostacyclin) and thromboxane B2 (a metabolite of thromboxane A2) were measured. The baseline production of 6-keto-prostaglandin F1alpha (63.9 +/- 8.8 ng/minute per gram of dry weight tissue, mean +/- SE, N = 10) or that of thromboxane B2 (1.3 +/- 0.2 ng/minute per gram, N = 10) were unaffected by nicotine. To study the effect of nicotine on thromboxane A2 synthesis by the fetal platelets, thrombin-induced platelet aggregation and consequent thromboxane A2 synthesis were allowed to occur in the whole cord blood in the absence or presence of nicotine (10 to 500 micrograms/mL). Nicotine inhibited concentration dependently platelet thromboxane A2 synthesis from the baseline level (107.3 +/- 7.1 ng/mL) by 15 to 93%. This inhibition was also seen in thromboxane A2 synthesis starting from exogenous arachidonic acid, suggesting that nicotine inhibits either cyclooxygenase and/or thromboxane A2 synthetase in the fetal platelets. Thus, nicotine is hardly responsible for maternal smoking-induced changes in fetal prostacyclin formation.

Biochemical and clinical effects of treating the premenstrual syndrome with prostaglandin synthesis precursors

The clinical and biochemical effects of a prostaglandin synthesis precursor (Efamol) containing linoleic acid and its metabolite, gamma-linolenic acid, were studied in 30 women with severe, incapacitating premenstrual syndrome. Efamol treatment alleviated the premenstrual symptoms in general and depression especially better than did a placebo. The capacity of platelets to release thromboxane B2 during spontaneous clotting was decreased in patients undergoing Efamol treatment (141 +/- 59 ng/ml, mean +/- SD) as compared to those undergoing placebo treatment (186 +/- 44 ng/ml, p less than 0.01) and control subjects (176 +/- 40 ng/ml, n = 25, p less than 0.05). No changes were found in plasma 6-keto-prostaglandin F1alpha or in FSH, LH, prolactin, progesterone, estradiol and testosterone. The data suggest that prostaglandins might play a role in the pathophysiology of the premenstrual syndrome.

Differential inhibition of platelet thromboxane and lung prostacyclin production by sulphinpyrazone, acetylsalicylic acid and indomethacin by human tissues in vitro

To compare the inhibition of human platelet and lung cyclo-oxygenases by sulphinpyrazone (SP), acetylsalicylic acid (ASA) and indomethacin, we investigated their effects on platelet thromboxane A2 (TxA2) production during spontaneous clotting and on prostacyclin (PGI2) and TxA2 productions of superfused minced human lung. The synthesis of proaggregatory, vasoconstricting TxA2 and antiaggregatory, vasodilating PGI2 were evaluated by measuring the concentration of their stable metabolites thromboxane B2 (TxB2) and 6-keto-prostaglandin F1 alpha respectively, by radioimmunoassays. The basal platelet TxB2 production was 241.0 +/- 56.3 ng/ml (mean +/- SEM, n = 12). The concentrations needed for 50% inhibition of this production (IC50) were 41.3 mumol/l for sulphinpyrazone, 6.3 mumol/1 for ASA and 0.094 mumol/l for indomethacin. The lung generated 23.8 +/- 5.5 ng/g/min (mean +/- SEM, n = 6) of 6-keto-PGF1 alpha and 8.5 +/- 1.8 ng/g/min of TxB2. The IC50 values for pulmonary 6-keto-PGF1 alpha and TxB2 productions were 530.0 mumol/l for SP, 370.0 mumol/l for ASA and 50.0 mumol/l for indomethacin. Thus pulmonary cyclo-oxygenase, presumably originating from endothelial cells, was 13, 59, and 532 times more resistant to these prostaglandin synthesis inhibitors (PGI's) than platelet cyclo-oxygenase. These data suggest that there are considerable differences in the concentration ranges of various PGI's by which the PGI2/TxA2 balance can be shifted to a dominance of PGI2.

Plasma six-keto-prostaglandin F1 alpha and endocrine pancreatic function in the newborn infant of the diabetic mother

Plasma concentrations of 6-keto-prostaglandin F1 alpha (6-keto-PGF1 alpha), C-peptide and pancreatic glucagon and blood glucose levels were measured in 13 infants of insulin-dependent diabetic mothers at the age of 2 h. Plasma 6-keto-PGF1 alpha levels were lower in these infants when compared to those of healthy controls at the same age (p less than 0.05). Plasma 6-keto-PGF1 alpha correlated negatively with the C-peptide levels (r = -0.57; p less than 0.05) and positively with the pancreatic glucagon concentrations (r = 0.83; p less than 0.001) in the infants of diabetic mothers. No correlation with blood glucose concentrations was found. The data suggest that hyperinsulinemia in infants of diabetic mothers is associated with a decreased vascular prostacyclin production.

One milligramme of acetylsalicylic acid daily inhibits platelet thromboxane A2 production

To seek the lowest dose of acetylsalicylic acid (ASA) capable of inhibiting platelet thromboxane A2 (TxA)2 production, 18 healthy volunteers ingested 9 mg, 3 mg or 1 mg of ASA/day for twenty days and the release of TxB2 (a metabolite of TxA2) during the spontaneous clotting of blood was measured by radioimmunoassay. In addition, the production of prostacyclin (epoprostenol, PGI2) was investigated by measuring the urinary excretion of its break-down product, 6-keto-prostaglandin F1 alpha (6-keto-PGF1 alpha) by radioimmunoassay. Significant inhibition of platelet TxA2 production was seen from the 15th day of treatment onwards with 1 mg of ASA (maximally 15%), from the 4th day of treatment onwards with 3 mg of ASA (maximally 40%), from the 1st day of treatment onwards with 9 mg of ASA (maximally 67%). No ASA dose changed platelet counts or urinary 6-keto-PGF1 alpha excretion. One mg of ASA daily, is the lowest dose ever shown to inhibit platelet TxA2 production.

Serum selenium and glutathione peroxidase, and plasma lipid peroxides in uterine, ovarian or vulvar cancer, and their responses to antioxidants in patients with ovarian cancer

The concentrations of serum selenium and plasma lipid peroxides, and the activity of serum glutathione peroxidase (GSH-Px) were measured before any therapy in patients suffering from uterine, ovarian or vulvar cancer, and in association with 1-day combination cytotoxic chemotherapy of ovarian cancer following 1-week supplementation with selenium (96 micrograms/day), vitamin E (300 mg/day), selenium and vitamin E, or placebo. Patients with gynaecological cancer (N = 44) had lower serum concentration of selenium (1.15 +/- 0.04 S.E. mumol/l; P less than 0.05) and serum activity of GSH-Px (404 +/- 13 units/l, P less than 0.01) than the control subjects (N = 56; 1.25 +/- 0.03 mumol/l and 444 +/- 8 units/l, respectively). In association with cytotoxic chemotherapy selenium alone (P less than 0.05), vitamin E alone (P less than 0.05) and both of them together (P less than 0.001) decreased the plasma concentration of lipid peroxides, and the combination of selenium and vitamin E also increased the activity of serum GSH-Px (P less than 0.01). During placebo, cytotoxic chemotherapy did not affect plasma lipid peroxides but it decreased (P less than 0.001) the activity of GSH-Px. Selenium inhibited this effect. Our data suggest that antioxidative mechanisms of patients with gynaecological cancer may be defective and that treatment with selenium and vitamin E results in changes of biochemical factors related to lipid peroxidation.

Thromboxane B2 production by fetal and neonatal platelets: effect of idiopathic respiratory distress syndrome and birth asphyxia

To study the production of proaggregatory thromboxane A2 (TxA2) by fetal and neonatal platelets, blood specimens were collected from umbilical cords immediately after delivery at term (n = 22), from newborn infants during the first 10 days of life (n = 85), from infants between 1 and 3 months of age (n = 14), and from healthy adults (n = 18). The blood samples were allowed to clot spontaneously at +37 degrees C for 60 min, and the concentrations of thromboxane B2 (TxB2), a stable metabolite of TxA2, in the sera were measured by radioimmunoassay and expressed as nanograms of TxB2/10(6) platelets. Platelet TxB2 generation in term infants at the age of 1 day (1.344 +/- 0.253 ng/10(6) platelets, mean +/- SE, n = 9) was higher than that in cord blood (0.634 +/- 0.042 ng/10(6) platelets, n = 22), or in infants of 1-3 months of age (0.881 +/- 0.099 ng/10(6) platelets, n = 14), or in adults (0.869 +/- 0.062 ng/10(6) platelets, n = 18). Increase in TxB2 generation following birth was seen already at the age of 1 h (1.076 +/- 0.114 ng/10(6) platelets, n = 9). TxB2 synthesis in preterm infants (1.032 +/- 0.136 ng/10(6) platelets, n = 10) did not differ from that in term infants on the 1st day of life, and idiopathic respiratory distress syndrome had no effect on it (1.029 +/- 0.079 ng/10(6) platelets, n = 19). Severe birth asphyxia was accompanied by reduced TxB2 formation (0.564 +/- 0.201 ng/10(6) platelets, n = 7).(ABSTRACT TRUNCATED AT 250 WORDS)

Lipid peroxides, prostacyclin, and thromboxane A2 in runners during acute exercise

We studied the effect of physical activity on lipid peroxidation and on the production of antiaggregatory, vasodilatory prostacyclin (epoprostenol, PGI2) and its endogenous antagonist, thromboxane A2 (TxA2) in 10 well-trained long-distance runners before, during, and after maximal exercise on a cycle ergometer. Pre-exercise levels of lipid peroxides (2.0 +/- 0.4 mumol X l-1, means +/- SD), plasma immunoreactive 6-keto-prostaglandin F1 alpha (i 6-keto-PGF1 alpha, a metabolite of PGI2) (192.8 +/- 51.7 pmol X l), and serum immunoreactive thromboxane B2 (i TxB2, a metabolite of TxA2) (703.3 +/- 290.1 nmol X l) did not differ from those of 10 non-athletic controls. Plasma i 6-keto-PGF1 alpha was increased at the seventh minute of the exercise test, but not any more at the end of the exercise or 30 min later. Lipid peroxides or i TxB2 did not change. Our data suggest that the changes of the PGI2/TxA2-ratio induced by long-term or acute physical exercise are too small to explain the protective effect of physical fitness against coronary heart disease.