Prostaglandins in renovascular and renal hypertension

PG A1, B1, E2, F1,2alpha and PRA have been measured in 8 hypertensive patients with unilateral renal arterial stenosis, 7 hypertensive patients with unilateral renal atrophy and 20 control normotensive subjects. PRA and PGA1 were significantly increased in patients with renovascular hypertension but not in patients with atrophy. PGE2 and PGF1,2alpha were increased in both groups of patients, especially on the stenotic or atrophic side. The increase of PGA1 and PGE2, represents a secondary antihypertensive, diuretic and natriuretic mechanism, the increase of PGF1,2alpha a direct hypertensive mechanism.

Renal prostaglandins in the control of renin

The biochemical processes which transform baroreceptor, beta-adrenergic and macula densa signals into an increase or a decrease of renin secretion are unknown. Evidence is presented that the renal PG system is intimately involved in the mechanisms regulating the release of renin. In vivo stimulation of renal PG synthesis by arachidonic acid (C20:4) or furosemide increases renin release. PG synthesis inhibitors decrease basal renin release and reduce the renin release following stimulation with C20:4, furosemide and renal ischemia. In vitro, C20:4 and the PG-endoperoxides stimulate renin release from the rabbit kidney cortex whereas PGF2alpha inhibits it. This suggests an intrinsic role in the renin release mechanism of PGs, synthesized at or near the juxtaglomerular apparatus. The operation of this PG effect on renin release may depend upon a salt intake related control of PG synthesis and of conversion of PGE2 to PGF2alpha. Increased or decreased renal PG synthesis may also be the primary event leading to elevated or reduced renin levels in some clinical disorders. In Bartter's syndrome, the elevated renin levels may result from an increase in PG synthesis or a decrease of PGF2alpha formation. In benign, uncomplicated essential hypertension, decreased renal PG synthesis or increased PGS2alpha formation may be the primary mechanism which reduces renin release and renal blood flow.

Prostaglandins and renal function

Prostaglandins modulate the effects of vasoactive hormones by attenuating the renal actions of the renin-angiotensin system and contributing to and, perhaps, mediating some of those of the kallikrein-kinin system. A prostaglandin mechanism participates in the regulation of renin and erythropoietin release. When renal function is compromised, the circulation to the kidney is sustained by a major prostaglandin component withdrawal of which results in significant hemodynamic effects, particularly reduction of blood flow to the inner cortex and medulla.

The effect of parenteral lipid emulsions on pulmonary hemodynamics and eicosanoid metabolites in preterm infants: a pilot study

BACKGROUND

Soy-based intravenous fat emulsion (IVFE) is known to cause a rise in pulmonary artery pressure in the preterm infant, thought to be mediated through eicosanoid metabolites of linoleic acid. We compared the effect of soy-based IVFE and an olive-oil-based IVFE containing less than half the content of linoleic acid on pulmonary artery pressure and eicosanoid metabolites in preterm infants receiving parenteral nutrition.

METHODS

In this pilot study at a regional neonatal intensive care unit (ICU), infants received either a soy-based or olive-oil-based IVFE as part of an otherwise identical feeding protocol. Pulmonary artery pressure and urinary thromboxane B2 and prostaglandin F1 alpha were measured at baseline and maximum lipid infusion.

RESULTS

There was a greater fall in pulmonary artery pressure in the olive-oil-based IVFE group compared with the soy-based IVFE group. A decrease in urine thromboxane/prostaglandin F1 alpha ratio was seen only in the olive-oil-based IVFE group.

CONCLUSIONS

In the parenterally fed preterm infant, an olive-oil-based IVFE may have a beneficial effect on pulmonary artery pressure when compared with soy-based IVFE. Effects on pulmonary vascular tone are likely to be mediated through alterations in eicosanoid metabolism. A randomized trial is warranted to compare the effects of different lipid emulsions.

Influence of ShuJinHuoXue tablets on ischemia reperfusion injury of animals' skeletal muscle

Ischemia-reperfusion (IR) can lead to serious tissue oxidative injury in animals. ShuJinHuoXue tablet (SJHXT) is a Chinese Traditional Medicine which can relax the muscles and stimulate the blood circulation and has been used as a clinical medicine. In the present study, we investigated the effects of SJHXT pretreatment on oxidative injury using an animal model of acute limb IR. Results showed that SJHXT pre-treatment (200, 300 and 400 mg/kg/day) markedly reduced serum endothelin-1 (ET-1), thromboxane B2 (TXB₂) levels and thromboxane B2/6-keto- prostaglandin F1α (TXB₂/6-Keto-PGF(1α)), wet weight/dried weight (W/D) ratio, myeloperoxidase (MPO), creatine kinase (CK), lactate dehydrogenase (LDH) activities, and increased serum nitric oxide (NO), 6-Keto-PGF(1α) levels and NO/ET-1 ratio in the IR+SJHXT groups. In addition, the SJHXT pre-treatment (200, 300 and 400 mg/kg/day) markedly reduced skeletal muscle Ca²⁺, malondialdehyde (MDA) levels, increased Na⁺-K⁺-ATPase, Ca²⁺-Mg²⁺-ATPase, superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GSH-Px) activities. Our results suggest that SJHXT pre-treatment may improve skeletal muscle blood vessel microcirculation, decrease skeletal muscle oxidative injury and enhance antioxidant enzymes activities in IR animals.

Oxytocin (OT) - und 13,14-Dihydro-15-Keto-PGF2α(PGFM)-Spiegel nach intrazervikaler PGE2-Gel-Gabe in Kombination mit Betamimetikaapplikation; biochemische Veränderungen und klinische Konsequenzen

Intracervical application of 0.4 mg PGE2 gel for achieving maturity of the cervix before necessary inducement of labour results in 1-2% of the cases in permanent contractions in association with foetal bradycardias (Goeschen and Saling, 6). This Complication can be removed by the administration of the beta-mimetic Fenoterol given by the intravenous route. Basing on this fact we tried to find out whether it would be possible to prevent an increase in labour activity by administering Fenoterol before applying PGE2 without impairing the softening effect, and also how the OT and PGFM concentrations in the plasma are affected. To clarify this, we compared the clinical and biochemical results obtained in 5 patients who had been given 5 mg Fenoterol orally before receiving 0.4 mg PGE2 gel, with the results obtained in patients who had been treated without any previous Fenoterol administration with either 0.4 mg PGE2 (n = 10), 0.8 mg PGE2 (n = 6) or placebo gel (n = 5). In all groups treated with the preparation were obtained significant differences compared with the placebo group in respect of maturation of the cervix. Oral administration of Fenoterol did not produce any weaking of the softening effect; an increase of the dose to 0.8 mg did not result in an enhancement. After intracervical administration of 0.4 mg PGE2 gel the PGFM values remained unchanged with and without Fenoterol administration; the same was true also after 0.8 mg PGE2 and after placebo. As with spontaneous labour, a significant PGFM increase was seen only if the cervical diameter had attained 7 cm or more.(ABSTRACT TRUNCATED AT 250 WORDS)

Conception rate and reproductive function of dairy cows fed different fat sources

The objective of the experiment was to determine the effects of fat supplementation on cyclicity, progesterone concentration, follicular development, conception rate, embryo mortality, and plasma concentrations of prostalglandin F metabolite (PGFM) in cattle. The hypothesis of this experiment was that feeding flaxseed, which is a source rich in C18:3, would increase conception rate of dairy cows due to decreased plasma PGFM concentrations. A total of 138 lactating Holstein cows were allotted at calving to three groups of 46 cows, blocked for similar calving dates. Cows within each block were assigned to one of three isonitrogenous, isoenergetic, and isolipidic supplements based on either whole flaxseed (FLA), Megalac (MEG) or micronized soybeans (SOY). The diets were fed from calving to Day 50 of pregnancy for pregnant cows, or 120 day postpartum for those not diagnosed pregnant after AI. Detailed measurements of PGFM and follicle dynamics were only made on four cows for FLA and five cows for both MEG and SOY. The response in PGFM concentration following the oxytocin challenge administered around Week 11 of lactation was similar over time among treatments. Plasma progesterone concentrations from Days 17 to 21 of the estrous cycle starting around Week 9 of lactation and determined on a subsample of cows (n=for FLA and n=5 for both MEG and SOY) were higher for cows fed FLA than for those fed SOY (P=0.04) or MEG (P=0.06). Conception rates were similar among treatments. Total embryo mortality was lower (P=0.07) for cows fed FLA (0%) compared to those fed either MEG (15.4%) or SOY (8.0%). The mean size of the CL measured during a complete estrous cycle from Week 9 of lactation was smaller for cows fed SOY (16.3 mm) compared to those fed either FLA (19.1 mm) or MEG (18.3 mm). We inferred that pregnancy losses could be reduced by feeding whole flaxseed as a result of its effects on different factors such as modulation in concentration of progesterone and size of the CL.

Relation of C-reactive protein to oxidative stress and to endothelial activation in essential hypertension

BACKGROUND

C-reactive protein (CRP) predicts cardiovascular outcome. Oxidative stress is considered to be involved in endothelial alteration. We hypothesized that in essential hypertension (EH), oxidative stress, as measured by 8-iso-prostaglandin-F(2alpha) (8-iso-PGF(2alpha)), should be associated with increased CRP and endothelial activation, as evaluated by soluble intercellular adhesion molecule-1 (ICAM-1) and vascular adhesion molecule-1 (VCAM-1) plasma levels.

METHODS

In 83 subjects with mild EH and in 50 healthy control subjects we measured, in basal conditions, plasma levels of hs-CRP, 8-iso-PGF(2alpha), ICAM-1 and VCAM-1, and tumor necrosis factor-alpha (TNF-alpha).

RESULTS

Subjects with EH had higher levels of 8-iso-PGF(2alpha) (P < .0001), CRP (P < .001), ICAM-1 and VCAM-1 (P < .001), and TNF-alpha (P < .001) than did control subjects. We divided successively EH according to CRP values (<1, 1-3, >3 mg/L), and we observed increasing and significantly different levels of the endothelial parameters and of TNF-alpha along with increasing CRP. Linear analysis of correlation pointed out significant correlation of CRP with 8-iso-PGF(2alpha) (r = 0.730, P < .001), ICAM-1 and VCAM-1 (r = 0.642 and 0.468, P < .001 respectively), and TNF-alpha (r = 0.609, P < .001). Multiple regression analysis using CRP as a dependent variable confirmed the relationship of CRP with systolic blood pressure (beta 0.216, P = 0.039) and with 8-iso-PGF(2alpha) (beta 0.602, P = .0001).

CONCLUSIONS

Our data demonstrate that in EH, inflammatory molecules such as CRP and TNF-alpha are increased and related to both oxidative stress and endothelial activation.

Plasma levels of nitrites, PGF1α and nitrotyrosine in LPS-treated rats: functional and histochemical implications in aorta

We investigated the effects of lipopolysaccharide (LPS) administration on plasma nitrite, nitrotyrosine and 6-keto prostaglandin F1alpha, (PGF1alpha) levels and the related resultant changes in function and histochemistry of aorta in rats. Plasma nitrite and PGF1alpha nitrotyrosine levels were analysed after 5 mg/kg intravenous LPS was administered to rats compared with those in non-treated rats. The distribution of nitrotyrosine in the aorta was studied immunohistochemically. The contractile responses of aortic rings to phenylephrine (PE) from both the LPS-treated and control rats were studied in the organ baths. There were increases in plasma nitrite, PGF1alpha, and nitrotyrosine concentrations of LPS-treated rats compared to non-treated rats. Immunoreactivity of nitrotyrosine residues were detected in the endothelial and smooth muscle cells in LPS-treated but not in control rat aorta. The contractile responses to PE of the LPS-treated rat aortic rings were significantly reduced as compared with those of control rat's. Incubation of the aortic rings from LPS-treated rats with cyclooxygenase inhibitor indomethacine or with a combination of indomethacine and nitric oxide synthase inhibitor N(omega)-nitro-L-arginine methyl ester (L-NAME) increased the contractile responses to the levels observed in control rats suggesting that both prostanoids and particularly nitric oxide (NO) are involved in the reduced contractile responses in LPS-treated rats. These results supported the view that LPS might cause an increment in both NO and PGI2 levels. This increase in the NO and PGI2 levels may be responsible from the reduction in responses of aorta to contractile agents in LPS-treated rats. Increased peroxynitrite formation in LPS-treated rats may lead to nitration of the tyrosil residues of the proteins in the aorta.

Effects of nitric oxide and prostacyclin on hemodynamic response by big endothelin-1 in near term fetal sheep

AIMS

To measure plasma concentrations of endothelin (ET)-1, NO metabolites (nitrate/nitrite; NOx) and 6-keto PGF1 alpha (PGF1 alpha) in maternal and fetal sheep blood, and to evaluate the effects of big ET-1 on hemodynamic response, blood gases and NO and 6-keto PGF1 alpha production in near term fetal sheep.

METHODS

Hemodynamic parameters were measured during infusion of big ET-1 into the carotid vein in chronically catheterized fetal sheep on day 125 of gestation. Fetal arterial blood samples were obtained for ET-1, PGF1 alpha) and nitrate/nitrite (NOx) measurements.

RESULTS

ET-1, NOx and PGF1 alpha plasma concentrations were all significantly higher in fetal compared with the maternal plasma. Big ET-1 significantly decreased fetal systolic and diastolic blood pressure and significantly increased fetal heart rate. Big ET-1 stimulated plasma PGF1 alpha), but not NOx , concentration.

CONCLUSIONS

Circulatory regulating factors in the fetus were up-regulated. The effects of ET-1 on fetal hemodynamic response may be mediated via prostacyclin, but not via the NO pathway.

Effect of intrauterine infusion of Escherichia coli on hormonal patterns in gilts during the oestrous cycle

The aim of this study was to determine the effect of intrauterine Escherichia coli infusion on the patterns of plasma LH, prolactin, progesterone, androstenedione, testosterone, oestrone, oestradiol-17beta, cortisol and 13,14-dihydro-15-keto-prostaglandin F2alpha (PGFM) in gilts during the oestrous cycle. On day 4 of the oestrous cycle (day 0), 25 mL of saline or 25 mL of Escherichia coli suspension, containing 10(7) colony forming units x mL(-1), was infused once into the each uterine horn in group I or II respectively. The control gilts developed a new oestrous cycle at the expected time but not bacteria-treated. Endometritis and vaginal discharge developed in all gilts after Escherichia coli infusion. The administration of Escherichia coli resulted in a reduction of plasma levels of LH, prolactin, oestrone and oestradiol-17beta (P < 0.05-0.001), mainly on days 15-18 after treatment (expected perioestrous period). During this time, the plasma androstenedione level was elevated (P < 0.05-0.001) after bacteria infusion. In the gilts receiving bacteria, progesterone concentration decreased from day 8 after treatment and was low until the end of the study (P < 0.05-0.001). On days 8-12 after bacteria administration, the level of PGFM was higher (P < 0.001) than that found in the control group. These results suggest that the developing inflammatory process of the endometrium in gilts following Escherichia coli infusion significantly affects the pituitary-ovarian axis function as well as prostaglandin production leading to anoestrus.

Effect of flunixin meglumine on selected physiologic and performance parameters of athletically conditioned thoroughbred horses subjected to an incremental exercise stress test

Twelve clinically sound, healthy, athletically conditioned Thoroughbred horses were subjected to an incremental exercise stress test to determine the effects and period of detection of a single dose of flunixin meglumine (1.1 mg/kg by intravenous injection) in serum and urine by ELISA. Flunixin concentrations, performance, and hematologic and clinical chemical parameters were measured. All horses were rotated through four treatment groups of a Latin-square design providing for each horse to serve as its own control. Flunixin meglumine reduced prostaglandin F(1alpha) and thromboxane concentrations that had been increased by intense exercise. Performance parameters did not improve and prostaglandin concentrations did not significantly correlate with total run time. Exercise did not change the flunixin elimination profile in either serum or urine, and concentrations were found to be below the detection limit of the ELISA test within 36 hours in serum and 120 hours in urine.

Maintaining carotid flow by shunting during carotid endarterectomy diminishes the inflammatory response mediating ischaemic brain injury

OBJECTIVES

to assess whether shunting during carotid reconstruction affects the release of inflammatory mediators from the ipsilateral hemisphere.

MATERIALS AND METHODS

a catheter was placed in the ipsilateral jugular bulb during carotid endarterectomy (CEA) in 20 patients. Eight patients with ICBP (internal carotid backpressure) <40 mmHg received a shunt during CEA and 12 patients with ICBP >40 mmHg were operated upon without a shunt. Four patients with a carotid body tumour were used as controls. Blood was taken from the catheter as well as from the radial artery; before clamping, 5, 15, 30 min after clamping and 5 min after declamping. The oxygen extraction (AVO(2)) was calculated. Plasma concentrations of interleukin-1beta (IL-1beta), phospholipase A(2)(PLA(2)), thromboxane B(2)(TXB(2)), 6-keto-prostaglandin F1alpha (6-keto-PGF1alpha) and prostaglandin E(2)(PGE(2)) were measured by enzyme-linked immunosorbent assay (ELISA) technique.

RESULTS

all patients had a normal postoperative course except for one patient in the no-shunt group, who suffered a stroke 1 h later due to occlusion of the endarterectomy site. The AVO(2)extraction increased during clamping in patients operated upon without a shunt (p <0.05). This increase was partly recovered to pre-clamp levels 5 min after reperfusion. The extraction remained stable in the non-shunted patients and the control group. The increased extraction in the non-shunted group correlated with increased levels of IL-1beta during clamping ( p <0.05) and reperfusion ( p <0.01). PLA(2)also increased during reperfusion in the non-shunted group ( p <0.05). An increased ratio between TXB(2)and 6-keto-PGF1alpha was noted during clamping ( p <0.05) and further increased during reperfusion. The levels of PGE(2)remained stable in both CEA groups. The PLA(2)levels, as well as TXB(2), 6-keto-PGF1alpha and PGE(2)levels, remained unchanged during the procedure in the control group.

CONCLUSIONS

there is a metabolic response to carotid cross-clamping when no shunt is used. However, the clinical significance of this is unclear, since there were no intraoperative strokes.

Prostaglandin F concentration in serum of hens and cocks

Prostaglandin F (PGF) concentrations in the serum of laying and nonlaying hens and of cocks at various times during a day were measured by radioimmunoassay. The serum concentration of PGF was higher in laying hens than in nonlaying hens or cocks without regard to time of day. In all birds, the concentration showed a peak at 2 h after onset of light (0700 h). In laying hens on the day of laying the fourth egg of a sequence, two peaks were found: one at 2 h after onset of light and another at the time immediately after oviposition. The results suggest that the serum concentration of PGF in both male and female chickens shows a daily change and that in laying hens it also shows a change associating with oviposition.

Ibuprofen does not impair renal function in patients undergoing infrarenal aortic surgery with epidural anaesthesia

OBJECTIVE

To investigate the effect of preoperative ibuprofen administration on renal function during and after infrarenal aortic surgery under thoracolumbar epidural anaesthesia (EPA).

DESIGN

A prospective randomised, double-blinded clinical study.

SETTING

Operation room and intensive care unit in a university hospital.

PATIENTS

Twenty-six consecutive patients scheduled for elective infrarenal aortic surgery.

INTERVENTIONS

The patients were prospectively randomised to receive 400 mg ibuprofen intravenously (i.v.) or a placebo aliquot before surgery.

MEASUREMENTS AND RESULTS

We assessed renal function by calculating creatinine clearance, and fractional sodium excretion before surgery (baseline), 1 h after cross-clamping (intraoperative), 6 h after cross-clamping (postoperative) and 24 h after cross-clamping (on the 1 st postoperative day). At each point in time, we additionally registered haemodynamics and determined the plasma concentration of 6-keto-PGF1alpha (stable metabolite of prostacyclin, PGI2), bicyclic PGE2 (stable metabolite of PGE1 E2), active renin, aldosterone and vasopressin by radioimmunoassays. Throughout the observation period the renal function parameters mostly remained within the normal range without a significant difference between ibuprofen- and placebo-treated patients (creatinine clearance: baseline 41 +/- 3 vs 38 +/- 6, intraoperative 57 +/- 8 vs 64 +/- 11, postoperative 64 +/- 9 vs 56 +/- 9, first postoperative day 43 +/- 5 vs 47 +/- 6 ml x min x m(-2), means +/- SEM). The plasma levels of 6-keto-PGF1alpha (68 +/- 8 vs 380 +/- 71* ng x l(-1)), bicyclic PGE2 (57 +/- 5 vs 88 +/- 9* ng x l(-1)) and vasopressin (14 +/- 7 vs 45 +/- 10* ng x l(-1), p < 0.0125), however, were significantly higher during the intraoperative period in the placebo-treated patients.

CONCLUSION

The inhibition of endogenous prostaglandin release by ibuprofen does not substantially impair renal function during infrarenal aortic surgery under EPA.

Prostaglandin production contributes to exercise-induced vasodilation in heart failure

Endothelial release of prostaglandins may contribute to exercise-induced skeletal muscle arteriolar vasodilation in patients with heart failure. To test this hypothesis, we examined the effect of indomethacin on leg circulation and metabolism in eight chronic heart failure patients, aged 55 +/- 4 yr. Central hemodynamics and leg blood flow, determined by thermodilution, and leg metabolic parameters were measured during maximum treadmill exercise before and 2 h after oral administration of indomethacin (75 mg). Leg release of 6-ketoprostaglandin F1alpha was also measured. During control exercise, leg blood flow increased from 0.34 +/- 0.03 to 1. 99 +/- 0.19 l/min (P < 0.001), leg O2 consumption from 13.6 +/- 1.8 to 164.5 +/- 16.2 ml/min (P < 0.001), and leg prostanoid release from 54.1 +/- 8.5 to 267.4 +/- 35.8 pg/min (P < 0.001). Indomethacin suppressed release of prostaglandin F1alpha (P < 0.001) throughout exercise and decreased leg blood flow during exercise (P < 0.05). This was associated with a corresponding decrease in leg O2 consumption (P < 0.05) and a higher level of femoral venous lactate at peak exercise (P < 0.01). These data suggest that release of vasodilatory prostaglandins contributes to skeletal muscle arteriolar vasodilation in patients with heart failure.

Reflux esophagitis and airway hyperresponsiveness

OBJECTIVES

To observe the effects of reflux esophagitis(RE) on the lung function and airway reactivity, and study the mechanism of airway hyperresponsiveness(AHR) in patients with RE.

METHODS

Lung function measurements and airway provocation tests were performed in 31 RE patients and 35 control subjects. TXB2 and PGF1a were determined in 20 cases of each group.

RESULTS

In RE patients the lung function was lower and the rate of AHR was higher than control subjects (P < 0.05). Among RE patients 25% had higher airway sensitivity (Dmin < 3 u). The TXB2 of RE patients with AHR was higher than those without AHR. Dmin correlated significantly with TXB2 (r = -0.653, P < 0.05).

CONCLUSIONS

RE could damage the lung function. The rate of AHR was 61%, the high airway sensitivity was probably potential asthma, and TXB2 may play a role in the pathogenesis of AHR.

Effect of iron overload and iron deficiency on atherosclerosis in the hypercholesterolemic rabbit

It has been suggested that iron plays an important role in the pathogenesis of atherosclerosis, primarily by acting as a catalyst for the atherogenic modification of LDL. Although some epidemiological data suggest that high stored iron levels are an independent risk factor for coronary artery disease and that iron has been detected in both early and advanced atherosclerotic lesions, the evidence is often contradictory and inconclusive. We used the New Zealand White rabbit to investigate the effects of iron overload (FeO) and iron deficiency (FeD) on atherosclerosis. Groups of 7 rabbits were either iron loaded by injections of iron dextran (FeO group), iron depleted by phlebotomy (FeD group), or given injections of saline (control group) for a total of 9 weeks. All rabbits were fed a chow diet containing 1% (wt/wt) cholesterol for the last 6 weeks of the study. Iron and antioxidant status and cholesterol levels were assayed in plasma before cholesterol feeding (week 3) and at the time that the rabbits were killed (week 9). In addition, the susceptibility of LDL to oxidation was measured and pathological examination of the aortic arch and thoracic aorta performed at the end of the study. FeD significantly decreased the levels of blood hemoglobin, serum iron, and transferrin saturation compared with controls. Conversely, FeO significantly increased transferrin Fe saturation. FeO but not FeD decreased plasma cholesterol levels compared with control animals both before (P < .05) and after (P = .055) cholesterol feeding. Neither FeO nor FeD had a significant effect on the levels of antioxidants and lipid peroxidation products in plasma and aortic tissue or on the susceptibility of LDL to ex-vivo oxidation. FeO significantly decreased aortic arch lesion formation by 56% compared with controls (P < .05), whereas FeD had no significant effect. These results indicate that in this animal model, FeO decreases rather than increases atherosclerosis, likely because iron dextran exerts a hypocholesterolemic effect. Our data do not support the hypotheses that elevation of Fe stores increases or that a reduction of Fe stores by phlebotomy decreases the risk of coronary artery disease.

[Pancreatic ischemia: a continuous injury factor in acute necrotic pancreatitis]

ANP model in rats was used to determine the concentration of TXB2, PGF1 alpha in plasma and the ACE activity in serum in five groups. The concentration of TXB2, PGF1 alpha in all experimental groups was significantly different from that of control group (P < 0.05). The comparison of ACE activity was just the same as the above except that of 6 h. The factors leading to pancreatic ischemia functioned continously. We conclude that pancreatic ischemia is a continuous injury factor in ANP, and there is no reperfusion-injury in the course of the disease.

[State of prostanoid-regulating function of the lungs in patients subjected to thoracic surgery]

Lung capacity to regulate the level of plasma prostanoids at the expense of their destruction or extra synthesis is one of their numerous non-gas-exchange functions. Prostaglandins A, E, and F, prostacyclin, and thromboxane were measured in the arterial and venous blood of 23 patients before and after surgery. The level of prostanoids was sharply increased in surgical patients. Substrates with the broncho- and vasoconstrictive action predominate in the blood of patients with obstructive and restrictive changes in the lungs, this eventually leading to complications in the postoperative period.

Evidence against an increase in capillary permeability in subjects exposed to high altitude

A potential pathogenetic cofactor for the development of acute mountain sickness and high-altitude pulmonary edema is an increase in capillary permeability, which could occur as a result of an inflammatory reaction and/or free radical-mediated injury to the lung. We measured the systemic albumin escape by intravenously injecting 5 muCi of 125I-labeled albumin and the plasma concentrations of cytokines, F2-isoprostanes (products of lipid peroxidation), and acute-phase proteins in 24 subjects exposed to 4,559 m. Ten subjects developed acute mountain sickness, and four subjects developed high-altitude pulmonary edema. The transcapillary escape rate of albumin was 6.9 +/- 2.0%/h (SD) at low (550 m) and 6.3 +/- 1.9%/h at high (4,559 m) altitude (P = 0.23; n = 24). The subjects with high-altitude pulmonary edema had a modest but insignificant increase in the transcapillary escape rate of albumin (4.6 +/- 1.9%/h at low vs. 5.7 +/- 1.9%/h at high altitude; P = 0.42; n = 4). Plasma concentrations of fibrinogen, alpha 1-acid glycoprotein, C-reactive protein, and interleukin-6 were unchanged in the early phases and significantly increased by the end of the observation period in the subjects with high-altitude pulmonary edema, whereas tumor necrosis factor-alpha and F2-isoprostanes did not change at all. This suggests that the inflammatory reaction was rather a consequence than a causative factor of high-altitude pulmonary edema. In summary, these data argue against a dominant role for increased systemic capillary permeability in the development of acute mountain sickness and high-altitude pulmonary edema.

[Effects of frostbite on some factors of blood coagulation system in rats under hypoxia]

The changes of some factors of blood coagulation system in rats following frost-bite of both hind feet under hypoxia were investigated. Male Wistar rats weighed 200 +/- 20g were divided into four groups: normal control (C); frostbite at normoxia (FN); frostbite during acute hypoxia (FAH) and frostbite during hypoxia after altitude acclimation (FHAC). Bleeding time and clotting time, rate of clot-retraction, plasma content of 6-keto-PGF1 alpha and TXB2 were determined following exposure to cold. The results showed that bleeding time and clotting time were shortened, and rate of clot-retraction was decreased, plasma content of 6-keto-PGF1 alpha and TXB2, T/P ratio were increased significantly after exposure to cold in all frostbite groups, but these changes were more prominent in FHAC than those in FN and FAH. The results demonstrated that there were changes in blood coagulation system following cold injury, blood coagulability was increased. These changes were closely related to the degree of frostbite. In addition, the degree of cold injury was aggravated by altitude acclimation and this may play an important role in the pathological process of dysfunction leading to necrosis of local frostbite tissue.

Influence of infection on patent ductus arteriosus and chronic lung disease in premature infants weighing 1000 grams or less

OBJECTIVES

To test the hypotheses that (1) infection increases ductal dilatory prostaglandins and inflammatory mediators that may influence the closure of a patent ductus arteriosus (PDA), increasing the incidence of late episodes of PDA (after 7 days) and the rate of closure failures, and (2) the concurrence of PDA and infection increases the risk of chronic lung disease (CLD).

METHODS

One hundred fourteen premature infants (birth weight, 500 to 1000 gm) were prospectively assessed for PDA and infection. Serum levels of 6-ketoprostaglandin F1 alpha and tumor necrosis factor alpha were measured routinely in all infants and when PDA or infection was present. Multivariate assessment of risk factors for PDA closure failure and for CLD was done by logistic regression, and expressed as an odds ratio and as 95% confidence intervals.

RESULTS

Late PDA episodes were more frequent in infants with infection than in those without infection. A temporally related infection (<5 days between both diagnoses) was associated with an increased risk of PDA closure failure (odds ratio, 19.1 (confidence interval, 4 to 90)). In addition to birth weight and the severity of initial respiratory failure, PDA and infection increased the risk of CLD (odds ratio, 11.7 (confidence interval, 1.7 to 81) for PDA; odds ration, 3.1 (confidence interval, 1 to 11) for infection). Furthermore, when both factors were temporally related, they further increased the risk of CLD (odds ratio, 29.6 (confidence interval, 4.5 to >100)). Infants with infection and those with PDA had higher levels of 6-ketoprostaglandin F1 alpha than did control subjects. Levels of tumor necrosis factor alpha were also elevated in infants with infection and in those with late PDA.

CONCLUSIONS

Infection adversely influences PDA outcome by increasing the risk of late ductal reopening and PDA closure failures. Increased levels of prostaglandins and tumor necrosis factor alpha in infants with infection may explain the poor PDA outcome. The concurrence of PDA and infection potentiates their negative effects on the risk of CLD.

[Low doses of acetylsalicylic acid effectively inhibits thrombocyte aggregation after ischemic stroke]

Platelet aggregation was examined in 43 patients after ischemic stroke and in 16 healthy subjects using multiparametric aggregation index (MAI). The value of MAI was significantly higher in stroke patients (3.15 in patients and 0.92 l/mumol in controls, p < 0.0001). Patients who had increased MAI (n = 26) were treated with a daily dose of 100 mg acetilsalicylic acid (ASA). Platelet activity was measured before and on the 7th and 28th day of treatment measuring three parameters: MAI, spontaneous dysaggregation and collagen induced aggregation. All 3 methods showed a significant decrease in platelet aggregation on the 7th day of treatment, but further changes were not found on the 28th day. Serum levels of thromboxane-A2 (TXA2) and prostacycline (PGI2) metabolites (TXB2 and 6-keto-prostaglandin-F1 alpha) were determined before and on the 28th day of treatment. The effect of 100 mg ASA per day proved to be selective: comparing the serum levels before and after treatment, a significant decrease of TXB2 concentration was found without changes in the concentration of 6-keto-prostaglandin-F1 alpha. Evaluating MAI and the value of dysaggregation might reflect ineffectiveness of antiplatelet therapy in patients not responding to a daily dose of 100 mg of ASA. For these patients the increase of the daily dose of ASA, or changing to another antiplatelet drug might be recommended.

Liberation of vasoactive substances and its prevention with thromboxane A2 synthase inhibitor in pig liver transplantation

There are multiple causes of liver graft nonfunction in the early post-transplant period. Since a severe microcirculatory disturbance based on ischemia-reperfusion liver injury is considered to be the main underlying pathophysiology, it is suspected that various vasoactive substances are liberated after reperfusion of the graft. In order to investigate this matter, we conducted an experimental study with pig liver allotransplantation. Two groups of animals received donor grafts with or without thromboxane synthase inhibitor (sodium ozagrel), 1.25 mg/ kg body weight intravenously, given at the time of liver harvesting. All of the recipient animals in the treatment group (n = 10) survived longer than 7 days whereas three of ten animals in the control group died within 7 days. Serum lactate dehydrogenase (LDH) in the recipient serum at 1 h after reperfusion was significantly lower in the treatment group (915.1 +/- 167.3 U/l) than in the control group (1264.4 +/- 134.7 U/l). Serum thromboxane B2 (2261.7 +/- 1055.7 pg/ml) and endothelin-1 (6.3 +/- 2.2 pg/ml) after reperfusion in the treatment group were significantly lower than those in the control group (4220.0 +/- 1711.0 pg/ml and 11.2 +/- 3.1 pg/ml, respectively). Although serum angiotensin II after reperfusion tended to be lower in the treatment group than in the controls serum renin activity was less than 3 ng/ml in both groups of animals. There were no differences in the plasma endotoxin levels between the two groups. We conclude that the administration of sodium ozagrel to the donor animals provided better graft function in recipients than no such treatment. We speculate that the inhibition of thromboxane A2 production suppresses the liberation of other vasoconstrictive substances, preventing microcirculatory disturbance and, thereby, contributing to improved graft function after liver transplantation.

[Effects of platelet activating factor and platelet activating factor receptor antagonist on spinal cord blood flow after spinal cord injury]

Platelet activating factor (PAF) and PAF receptor antagonist BN52021 were respectively administered by intrathecal or intravenous injection in cats. We observed their effects on blood flow and TXB2/ 6-keto-PGF1 alpha ratio (T/K ratio) in injured spinal cord and its adjacent region (L2-L4)s after trauma. The results showed that gray matter and white matter blood flow at L2-L4 segment significantly decreased T/K ratio elevated evidently in PAF group as compared with simple spinal cord injury, while gray matter and white matter blood flow at L2-L4 segment significantly increased and T/K ratio markedly decreased in BN52021 group as compared with simple spinal cord injury group. The results demonstrate and that PAF is an important factor leading to spinal cord blood flow reduction after trauma, and that PAF receptor antagonist BN52021 can evidently improve spinal cord blood flow and relieve secondary damage after trauma.

Prevention of experimental hepatic metastasis with thromboxane synthase inhibitor

To investigate the effectiveness of thromboxane (Tx) synthase inhibitor in the prevention of experimental hepatic metastasis, an in vivo study was designed. Hepatic metastasis was brought about by injection of 1 x 10(5) cells of colon 38 tumor into the portal vein of C57 B1/65 mice. Seven groups (n = 16 in each group) received different treatments: with TxA2 synthase inhibitor (sodium ozagrel), 5, 10 or 15 mg/kg BW before tumor inoculation, and daily for the following 3 days, (groups A, B and C, respectively); with acetyl salicylic acid (aspirin), 1.0, 1.5 or 2.0 mg/kg BW (groups C, D, and E, respectively); a control group, inoculated with vehicle only. Serum TxB2, a stable metabolite of TxA2, and prostaglandin F1 alpha were measured. Labeling index for tumor proliferation by bromodeoxy-uridine radioimmuno-assay was also studied. Incidence of metastasis in groups A (60.5%), B (49.5%), C (43.0%), D (80.5%), E (66.0%) and F (58.4%) was less than that in the control group (100%). Tumor size, number of labeling index did not differ among the groups. Serum TxB2 (pg/ml) levels were significantly lower in all of the groups than in the control. Serum PGF1 alpha levels in the groups with aspirin were lower than those in sodium ozagrel. Tx synthase inhibitor is effective in the prevention of experimental hepatic metastasis when it is given before and immediately after tumor inoculation. As Tx synthase inhibitor leaves metabolic pathway to PGI2 production intact, it is more effective in the prevention of metastasis than aspirin since aspirin inhibits both thromboxane and PGI2.

Segmental pulmonary vascular resistance following wood smoke inhalation

OBJECTIVES

To locate the specific site (i.e., pulmonary arteries, veins, or capillaries) of increased pulmonary vascular resistance after wood smoke inhalation and to demonstrate whether the prostanoids, thromboxane B2 or 6-keto-prostaglandin F1 alpha, play a role in these vascular resistance changes.

DESIGN

Prospective, randomized, controlled trial.

SETTING

Laboratory at a university medical center.

SUBJECTS

Five mongrel dogs.

INTERVENTIONS

The isolated canine left lower lobe preparation was used to measure changes in the pressure drop across the pulmonary arteries, veins, and capillaries. The left lower lobe was surgically isolated and perfused by a pump primed with autologous blood. The arterial and venous occlusion technique and the vascular pressure-flow relationship were used to assess changes in pulmonary vascular resistance. After baseline measurements, the left lower lobe was exposed to wood smoke for 2.5 mins and measurements were repeated.

MEASUREMENTS AND MAIN RESULTS

Smoke exposure caused an immediate (5 mins post-inhalation) increase in the total pressure gradient across the lobe (baseline = 9.8 +/- 0.5 torr [1.3 +/- 0.06 kPa]); smoke inhalation = 24.3 +/- 3.9 torr [3.24 +/- 0.5 kPa]; p < .05). Total pressure drop was partitioned longitudinally into pressure drops across arteries, veins, and the middle vessels. The increase in total pressure drop was associated with a moderate increase in the pressure drop across the middle vessels (baseline = 1.1 +/- 0.2 torr [0.14 +/- 0.02 kPa]; smoke inhalation = 5.2 +/- 1.1 torr [0.69 +/- 0.14 kPa]; p < .05); a large increase in the pressure drop across the veins (baseline = 4.8 +/- 1.3 torr [0.64 +/- 0.17 kPa]; smoke inhalation = 20.7 +/- 3.4 torr [2.7 +/- 0.45 kPa]; p < .05), and no significant change in the pressure drop across the arteries (baseline = 3.7 +/- 0.4 torr [0.49 +/- 0.05 kPa]; smoke inhalation = 4.8 +/- 0.5 torr [0.64 +/- 0.06 kPa]; p = NS). Increases in the pressure drop across the middle and venous vessels were transient and no longer significantly different from baseline 15 mins after smoke inhalation. Similarly, analysis of the pulmonary artery/blood flow data demonstrated that the mean slope and pressure intercept were greater than baseline only at 5 mins postsmoke inhalation (p < .05). Thromboxane B2 did not significantly change from baseline values after smoke exposure and prostaglandin F1 alpha demonstrated a slight but significant decrease 30 mins postsmoke. Pulmonary edema was measured gravimetrically (wet/dry weight ratio) and smoke significantly increased lung water in the left lower lobe (wet/dry weight ratio = 6.55 +/- 0.4) as compared with the normal left upper lobe (wet/dry weight ratio = 4.97 +/- 0.2).

CONCLUSIONS

We conclude that smoke causes an intense but transient increase in the pressure drop across the venous segment that may accelerate the formation of pulmonary edema, which is not mediated by changes in thromboxane B2 or prostaglandin F1 alpha.

Influence of different flow modi during extracorporeal circulation on endothelial-derived vasoactive substances

Influences of shear stress on endothelin (ET) as well as prostacyclin (PGF) levels are common findings in different experimental settings. Thus, plasma levels of both substances seem to be a good tool to verify if different flow modi can be produced in blood vessels by generating pulsatile flow with a roller pump. In the present study, 20 patients scheduled for elective aortocoronary bypass operation were divided into two groups at random. One group was perfused with nonpulsatile (CON-group) and the other with pulsatile flow (PULS-group) during extracorporeal circulation. ET and PGF plasma levels were monitored perioperatively together with parameters of renal function and haemodynamic data. ET values were only slightly elevated at the end of extracorporeal circulation (mean baseline value; CON 3.1 pg/ml and PULS 3.2 pg/ml; mean maximal values at the end of cardiopulmonary bypass (CPB) 4.0 pg/ml and 3.9 pg/ml respectively). Prostacylin values (median baseline values: CON 56.7 pg/ml and PULS 57.1 pg/ml) peaked at the end of operation (median CON 117.8 pg/ml and PULS 137.5 pg/ml respectively) with a subsequent small decrease. No differences between the groups could be observed at any time point with respect to vasoactive substances, urine output (CON 6.5 ml/min and PULS 6.2 ml/min) or haemodynamics during CPB. This confirms studies emphasizing that no effective microvascular pulsatile flow is generated by conventional pulsatile flow-generating devices. In the present study, normothermia and a constant flow rate were maintained during CPB. Aortic cannulae (body-surface-related not maximal large diameters) were inserted. Altering these procedures may have led to more pronounced differences between the groups. All patients had an uneventful course after the operation. Similar to other reports, the present study was not able to demonstrate any benefit of pulsatile perfusion during extracorporeal circulation.

Inhibition of leukotriene B4 synthesis does not prevent development of acute renal failure following storage and transplantation

Compound BW B70C, a selective 5-lipoxygenase inhibitor was tested for its ability to reduce inflammatory damage in an in vivo rabbit model of renal storage and transplantation. Kidneys were stored at 0-2 degrees C for 48 hr prior to autografting. In controls, renal vein LTB4 levels rose significantly after 30 min reperfusion but fell after 2 hr to baseline. TxB2 levels remained at baseline for the 6 hr measured. 6-k-PGF1 alpha levels rose significantly after 1 hr of reperfusion and remained elevated thereafter. Histology after 6 hr reperfusion showed moderate-to-severe cortical edema and mild congestion. Infused colloidal carbon was retained in the perivascular area in a narrow band at the corticomedullary junction, indicating a zone of vascular permeability. At 3 days after transplant, kidneys exhibited widespread tubular necrosis and calcification but little inflammation. Serum creatinine and urea peaked between days 3 and 5. 3/6 rabbits showed no symptoms of renal failure after 3 weeks. Pretreatment with BW B70C prevented the increase in LTB4 but had little effect on TxB2 and 6-k-PGF1 alpha levels. Histology showed no amelioration of cortical edema at 6 hr and congestion and hemorrhage were exacerbated. BW B70C had no effect on either colloidal carbon retention or distribution but did significantly reduce tubular necrosis and calcification at day 3. There was very little inflammatory infiltrate. BW B70C treatment did not improve the long-term viability of transplanted kidneys: 2/6 rabbits showed no symptoms of renal failure after 3 weeks. These data indicate that inhibition of LTB4 synthesis by BW B70C does not prevent the development of acute renal failure following 48 hr hypothermic storage and transplantation.

Acute lung injury isolated to an in situ lung preparation causes sustained reflex cardiovascular depression in dogs

We tested the hypothesis that acute lung injury (ALI) isolated to a perfused in situ left lung preparation results in sustained reflex cardiovascular depression. Phorbol myristate acetate (PMA), an agent that activates neutrophils, administered into the isolated lung preparation of chloralose-anesthetized dogs resulted in ALI, as assessed by wet-to-dry weight ratios and histopathology, and significant decreases in heart rate (43%), mean arterial pressure (27%), aortic blood flow (29%) and maximum rate of change in left ventricular pressure (30%). Significant reflex effects occurred by 20 min after PMA administration and were sustained for 40 min (n = 7). Hemodynamic variables recovered when the left lung was denervated 60 min after PMA administration. Indomethacin administered into the isolated circulation before PMA (n = 5) did not significantly influence the ALI or reflex effects. Systemic atropinization (n = 6) prevented only the bradycardia. Left lung denervation before ALI (n = 3) prevented all reflex effects. We conclude that PMA administration into an isolated in situ lung preparation results in ALI and sustained reflex cardiovascular depression that is most likely elicited by pulmonary C-fiber stimulation and mediated by withdrawal of sympathetic efferent nerve activity.

Platelet activation in diabetic patients with asymptomatic atherosclerosis

We studied 27 non-insulin-dependent diabetics without apparent atherosclerosis (AS) to investigate whether abnormal platelet function is related to asymptomatic atherosclerosis in diabetes mellitus. The degree of AS was quantitatively evaluated by determining the intimal plus medial thickness (IMT) of the carotid artery wall with ultrasound high-resolution B-mode imaging. Based on our previous finding that the upper threshold of the IMT was 1.1 mm in healthy subjects, the patients were divided into the AS-positive group with the IMT > 1.1 mm, (n = 17) and the AS-negative group with the IMT < 1.1 mm (n = 10). Among five variables measured as the factors concerned with thrombogenesis, only plasma levels of beta-thromboglobulin (beta-TG) and platelet factor 4 (PF4) were significantly higher in the AS-positive group than in the AS-negative group. Chronic administration of pentoxifylline (300 mg/day) significantly reduced the abnormally high plasma levels of beta-TG and PF4 in 7 patients of the AS-positive group to normal levels, without lowering the normal plasma beta-TG and PF4 levels in the remaining 10 patients. Pentoxifylline treatment did not affect the plasma levels of the 3 other variables, von Willebrand factor, 6-keto prostaglandin F1 alpha and thromboxane B2. This study suggests that the progress of atherosclerosis in diabetes mellitus is associated with in vivo platelet activation and platelet activation does not occur in diabetics without carotid atherosclerosis. Pentoxifylline may impede the vicious cycle in which atherosclerosis is accelerated by platelet activation.

The contribution of endothelial cells to hyperacute rejection in xenogeneic perfused working hearts

The mechanisms leading to the hyperacute rejection of a vascularized xenograft are still incompletely understood. The first stage of the rejection process is when blood of the recipient comes into contact with the endothelium of the xenograft. A working heart model was used to examine endothelium-related processes and their impact on organ function. Pig hearts were perfused with porcine (autologous) or human (xenogeneic) blood. Cardiac function was evaluated by calculating the stroke work index, arteriovenous oxygen, coronary flow, and resistance. PgF1a as a marker of endothelial activation, its antagonist TXB2, and myoglobin reflecting myocardial damage were measured in the hemoperfusate. H&E and PAS staining and immunohistological demonstration of factor VIII-related antigen was performed. Xenogeneic perfused porcine hearts showed significantly less stroke work, a higher arteriovenous oxygen difference, and an increased coronary resistance. Factor VIII-related antigen could not be demonstrated immunohistologically on the endothelium after xenogeneic perfusion. PgF1a levels were significantly higher in the xenogeneic hemoperfusate, indicating endothelial cell activation. The concentration of myoglobin in the hemoperfusate remained within normal values and was similar during autologous and xenogeneic perfusion. Therefore endothelium-related processes are likely to affect the coronary circulation--thus being one mechanism leading to diminished cardiac performance during hyperacute rejection.

Evidence for the involvement of oxygen-derived free radicals in ischaemia-reperfusion injury

Six patients undergoing vascular reconstructive surgery were examined for evidence of oxygen-derived free radical (ORF) damage to the protein, immunoglobulin G (IgG). OFR damage was determined as an increase in the fluorescence (ex 360 nm em 454 nm) to ultraviolet absorption (280 nm) ratio of IgG, representing N-Formyl kynurenine and other as yet unidentified fluorophores. The IgG ratio was found to increase slightly during ischaemia and to undergo marked elevation upon reperfusion (275 +/- 405% baseline value at 40 min post-clamp; mean +/- sd). A high ratio was maintained post-reperfusion, even after 60 min reperfusion. Determination of thromboxane B2, (TXB2), leukotriene B4, (LTB4) and 6-keto prostaglandin F1 alpha, (PGF1a), revealed a decrease in their concentrations during ischaemia and a transient, marked increase on reperfusion. Only TXB2 concentrations were found to correlate with the IgG ratio (negative correlation, p < 0.05). No correlation was observed between von Willebrand antigen factor, a marker of endothelial cell damage and fluorescent IgG ratio. However, levels of the factor increased slightly during ischaemia and more sharply upon reperfusion. These preliminary results therefore suggest that a more likely source of the OFRs responsible for IgG damage is endothelial cell xanthine oxidase, rather than cyclo-oxygenase or lipoxygenase.

Microcirculatory functions in systemic sclerosis: additional parameters for therapeutic concepts?

To study the functional reactivity of the cutaneous microcirculation in progressive systemic sclerosis (PSS), hyperemic responses after arterial occlusion (3 min) and during local heating (42 degrees C) were investigated with simultaneous measurements of red blood cell flux and cutaneous oxygen tension (pcuO2) of the skin in female patients (n = 19) with PSS and in healthy female controls (n = 15). Additionally, serum levels of 6-keto-prostaglandin 1 alpha (PGF1 alpha), a stable metabolite of prostacyclin, were compared to the microcirculatory data, and both were used to evaluate further a standardized therapy with 10-d intravenous calcitonin (100 IU/d) infusion in six PSS patients. In PSS, the initial mean pcuO2 value was significantly reduced and was inversely proportional to flux and to PGF1 alpha levels, whereas the flux and pcuO2 responses to the above hyperemic stimuli showed significant reductions, revealing a pattern of "hyperemic hypoxia" probably due to exhausted functional reserves of cutaneous perfusion. During calcitonin infusion significant rises in pcuO2 and temporarily in PGF1 alpha and flux were found. After 10 d of therapy, increased pcuO2 was associated significantly with decreased flux, indicating a shifting of blood from deeper regulatory vessels to the subepidermal capillaries. Both clinical improvement and the results of microcirculatory measurements demonstrate a beneficial effect of calcitonin on the cutaneous microcirculation in PSS patients, possibly due in part to a short-term increase in release of endogenous prostacyclin from the vascular endothelium during the infusion. The disturbed reactivity of the dermal vessels in PSS is important for the evaluation of therapeutic concepts and stresses, together with the elevated PGF1 alpha plasma levels, vascular factors in the pathogenesis of PSS.

Endotoxemia in dairy cattle: role of eicosanoids in reticulorumen stasis

The role of arachidonic acid metabolites in the forestomach stasis induced by Escherichia coli endotoxin was evaluated. Six adult Holstein cows received saline solution; endotoxin at 1, 10, and 100 ng/kg of body weight; flunixin meglumine at 1.1 mg/kg of body weight; and flunixin meglumine at 1.1 mg/kg plus endotoxin at 100 ng/kg. The frequency of reticulorumen contractions, mental attitude, body temperature, respiratory rate, heart rate, and plasma concentration of prostaglandin E2, prostacyclin, and thromboxane were evaluated. Administration of saline solution and endotoxin at 1 ng/kg had no significant effects. Administration of endotoxin at 10 ng/kg did not cause significant clinical effects or alter reticulorumen contractions but enhanced synthesis of thromboxane. Administration of endotoxin at 100 ng/kg caused mild clinical signs of stasis, reduced the frequency of reticulorumen contractions, and enhanced synthesis of thromboxane and prostacyclin. Reticulorumen stasis was not accompanied by an increase in the plasma concentration of prostaglandin E2. Flunixin meglumine abolished endotoxin-induced reticulorumen stasis, tachycardia, and synthesis of arachidonic acid metabolites. Reticulorumen stasis during bovine endotoxemia is caused either by enhanced synthesis of an arachidonic acid metabolite other than prostaglandin E2 or by local synthesis of prostaglandin E2.

Perfusion pressure control by adenosine triphosphate given during cardiopulmonary bypass

Administration of exogenous adenosine triphosphate (ATP) as a vasodilator during cardiopulmonary bypass was assessed in consecutive adult patients (n = 24) who demonstrated a high arterial perfusion pressure (mean, > 90 mm Hg). The action of ATP was characterized by rapid induction and stabilization of the blood pressure level. The dose of ATP ranged from 0.68 to 2.68 mg/min. Within 1 minute after the administration, there was a significant reduction in the perfusion pressure from 102 +/- 18 mm Hg (mean +/- standard deviation) to 72 +/- 19 mm Hg. The ATP was then able to maintain the desired pressure of 69 +/- 12 mm Hg at 5 minutes, 67 +/- 12 mm Hg at 10 minutes, and consistent values thereafter. After the ATP administration was discontinued, there was a prompt recovery of pressure without bradyarrhythmia. The frequency and amount of inotropes used were consistent with the control group (n = 26). Although the administration of ATP reduced the increase in serum catecholamine concentration, there were no significant changes in other vasoactive mediators (eicosanoid, angiotensin II, endothelin) between the two groups during cardiopulmonary bypass. There was neither an accumulation of metabolic products (uric acid, phosphate) nor a decrease in the level of divalent cation (Ca2+), which is observed when the cations combine with phosphates or adenosine nucleotides. This study confirmed the efficacy and safety of ATP infusion during cardiopulmonary bypass.

Dietary palmitic and oleic acids exert similar effects on serum cholesterol and lipoprotein profiles in normocholesterolemic men and women

To compare the effects of dietary palmitic acid (16:0) vs oleic acid (18:1) on serum lipids, lipoproteins, and plasma eicosanoids, 33 normocholesterolemic subjects (20 males, 13 females; ages 22-41 years) were challenged with a coconut oil-rich diet for 4 weeks. Subsequently they were assigned to either a palm olein-rich or olive oil-rich diet followed by a dietary crossover during two consecutive 6-week periods. Each test oil served as the sole cooking oil and contributed 23% of dietary energy or two-thirds of the total daily fat intake. Dietary myristic acid (14:0) and lauric acid (12:0) from coconut oil significantly raised all the serum lipid and lipoprotein parameters measured. Subsequent one-to-one exchange of 7% energy between 16:0 (palm olein diet) and 18:1 (olive oil diet) resulted in identical serum total cholesterol (192, 193 mg/dl), low-density lipoprotein cholesterol (LDL-C) (130, 131 mg/dl), high-density lipoprotein cholesterol (HDL-C) (41, 42 mg/dl), and triglyceride (TG) (108, 106 mg/dl) concentrations. Effects attributed to gender included higher HDL in females and higher TG in males associated with the tendency for higher LDL and LDL/HDL ratios in men. However, both sexes were equally responsive to changes in dietary fat saturation. The results indicate that in healthy, normocholesterolemic humans, dietary 16:0 can be exchanged for 18:1 within the range of these fatty acids normally present in typical diets without affecting the serum lipoprotein cholesterol concentration or distribution. In addition, replacement of 12:0 + 14:0 by 16:0 + 18:1, but especially 16:0 or some component of palm olein, appeared to have a beneficial impact on an important index of thrombogenesis, i.e., the thromboxane/prostacyclin ratio in plasma.

[Blood lipids and characteristics of free radical processes in specific classes of lipoproteins in rats in the early periods after gamma-radiation]

The content of lipids and lipoproteins, the state of free-radical processes and the level of eicosanoids (prostaglandin F-1L and thromboxane B-2) have been studied in the blood plasma and in certain classes of lipoproteins in rats 2 and 24 h after external gamma-radiation in doses of 1.2 and 3 Gy. Hypertriglyceridemia and hyperprebetalipoproteinemia, whose expressivity increases with a radiation dose are revealed. The activation of free-radical processes, an increase of the thromboxane V-2 content and a decrease of the prostaglandin F-1L content are observed with a dose of 1 Gy.

Effects of naproxen on renal function in older patients with mild to moderate renal dysfunction

We have evaluated 45 elderly patients with both musculoskeletal problems and mild to moderate renal dysfunction. We treated these patients with a non-steroidal anti-inflammatory drug (NSAID) for 2 weeks. The serum creatinine, urinary creatinine clearance and blood pressure were monitored before and after therapy. In some patients serum levels of thromboxane B2 (TxB2) and the urinary prostaglandins E2 (PGE2) and I2 (prostacyclin) measured as 6-keto-PGF1 alpha were also monitored before and after therapy and correlated with the clinical measurements. This study has demonstrated that in the entire patient group, the trial drug was tolerated extremely well. There were no changes in the serum creatinine or in the urinary creatinine clearance after 2 weeks of therapy. There was also no change in the early morning diastolic blood pressure. In the 11 patients in whom the serum and urinary prostaglandins were measured, the serum thromboxane levels fell with therapy to a level of 1.5% of the initial value. The urinary levels of PGE2 also fell but not to the same degree. The urinary PGE2 levels fell to 28% of the baseline values. There was no significant change in the levels of urinary 6-keto-PGF1 alpha (prostacyclin). These observations suggest that prostacyclin may be the important prostaglandin in maintaining normal renal haemodynamics when patients are treated with NSAIDs.

Effect of endothelin-3 (ET-3) on renal function in rat perfused kidney

We examined the effect of endothelin-3 (ET-3) at a high dose (pressor dose) and a low dose (non-pressor dose) in rat perfused kidney (PK), since ET-3 has recently been reported to exert a vasodilator action especially at a low dose. Kidneys were perfused with Krebs-Henseleit buffer at a fixed flow rate (6 ml/min) in situ. After collection of the renal venous effluent and urine for 20 min, vehicle (saline; n = 6), 10(-13)M ET-3 (low dose; n = 6) or 10(-8) M ET-3 (high dose; n = 6) was added to the perfusate, and sample collection was performed for the same period with each. The high dose of ET-3 significantly increased the perfusion pressure, fractional sodium excretion and synthesis of prostaglandins (PGs) consistently with a significant reduction in the glomerular filtration rate (GFR). On the other hand, the low dose of ET-3 significantly increased the GFR, urine volume and free-water clearance with no change in the perfusion pressure or synthesis of PGs. These findings suggest that a low dose of ET-3 can increase the glomerular capillary ultrafiltration coefficient and that ET-3 exerts an influence on sodium and water handing in the rat PK.

[Plasma prostacyclin and thromboxane concentration in healthy children and in offspring of parents suffering from myocardial infarct]

6-keto-prostaglandin F1a and thromboxane B2 were determined by radioimmunoassay in 135 healthy children, as a control group, and in 125 offsprings of parents suffering from premature coronary artery disease. Plasma prostacyclin concentration had decreased in children with a positive family history of coronary artery disease. It was demonstrated a strong reduction of thromboxane level in boys from age 11 in endangered group while the thromboxane/prostacyclin ratio did not differ from the control. It was supposed that in adolescent sons of parents who have had an acute myocardial infarction before the age of 45, a compensatory mechanism exists to protect them from disturbances in regulation of the balance between prostacyclin and thromboxane.

Plasma estradiol-17 beta, progesterone, prostaglandin F, and prostaglandin E2 concentrations during natural oviposition in the loggerhead turtle (Caretta caretta)

Changes in plasma concentrations of steroids and prostaglandins (PGs) during natural nesting and oviposition in the loggerhead turtle were studied. Blood samples were obtained during nine distinct behavioral stages of oviposition. Emerging females had no detectable prostaglandin F (PGF) or prostaglandin E2 (PGE2) whereas plasma estradiol-17 beta averaged 255 pg/ml and mean plasma progesterone was 395 pg/ml. Plasma steroid concentrations did not vary significantly during nesting. In contrast, plasma PGF and PGE2 exhibited significant elevations during nest digging about 15 min after emergence. A further significant increase in plasma PGs was observed 10 min later during early oviposition. Plasma PGE2 peaked during mid oviposition whereas maximal plasma PGF levels occurred during nest covering although mean values were not significantly different than those observed during oviposition. Both PGs showed an abrupt decline (within 10 min) during body pit covering to concentrations similar to those observed during nest construction. Our data suggest that PGs have an active role during oviposition and nesting in the loggerhead turtle and are consistent with hypotheses that PGF2 alpha stimulates uterine contractions promoting egg expulsion while PGE2 may be more important in promoting cervical relaxation.

[Endocrine activity of pseudolaric acids A and B and their effects on sex hormones, prostaglandins, uteri, and fetuses]

Two novel diterpendoids, pseudolaric acids A and B (PA, PB) first isolated from the root of Pseudolarix kaempferi Gorden in China, have been reported to possess significant antifertile activities in rats, hamsters, rabbits, and dogs. The present study demonstrated that neither PA nor PB had estrogenic and antiestrogenic activities, they also did not inhibit deciduous formation. When an effective dose of PB 30 mg.kg-1 was given on d 6 of pregnancy and the hormonal determinations were done on d 8 and d 12 of pregnancy, the progesterone, estradiol and prostaglandins E, F levels in plasma and the uterine prostaglandin E, F levels were not significantly reduced vs those of the control rats. The human uterus was used as the experimental material in vitro. PA and PB 200 micrograms.ml-1 cultural medium (McCoy's 5a medium) damaged only a part of the decidual and trophoblast cells. In partially depolarized isolated uterine smooth muscles of early pregnant rats, PA and PB caused a decline in the contractile tension. A low dose of PB 2 mg.kg-1.d-1 was given ig on d 6-12 of pregnancy in rats caused the body weight and the length of fetuses and the placental weight value significantly lower than those of the control. Thus, ischemia due to the vasoconstrictor effect is probably of great, and sometimes of supreme, importance.

Relation between changes of TXB2 and PGF1 alpha and the severity of the disease and pathological lesions in cases of severe icteric hepatitis

Clinically, 32 cases of intrahepatic cholestasis and 30 cases of severe chronic hepatitis with a bilirubin level higher than 171 mumol/L were studied. The results showed that bilirubin was 420 mumol/L in the first group, and 480 mumol/L in the second group (P greater than 0.05); TXB2 was 306 pg/ml and 271 pg/ml (P greater than 0.05) while PGF1 alpha was 253 pg/ml and 494 pg/ml (P less than 0.05) respectively, both were higher than their normal values (P less than 0.01). The cases were divided into acute, moderate and severe types according to their pathological lesions. Experimentally, intra- and extrahepatic cholestasis and necrotic liver tissues were induced by ANIT, ligation of common bile duct, and carbon tetrachloride respectively. Bilirubin was 629 mumol/L, 124.8 mumol/L, and lower than 17.1 mumol/L (P less than 0.01); plasma TXB2 was 634 pg/ml, 1036 pg/ml, and 239 pg/ml (P less than 0.01); PGF1 alpha was 186 pg/ml, 218 pg/ml, and 868 pg/ml (P less than 0.01) in the three groups respectively. No statistic difference was found in their TXB2 and PGF1 alpha. Our studies suggested that plasma TXB2 and PGF1 alpha in the liver was not related to the severity of liver lesions. TXB2 and PGF1 alpha are positively correlated with the increase of bilirubin while TXB2 is negatively correlated with PGF1 alpha, which might serve as an index for cholestasis, and be a cause for deepening jaundice.

Prostacyclin and prostaglandin E2 mediate reduction of increased mean arterial pressure during cardiopulmonary bypass by aspiration of shed pulmonary venous blood

Increased mean arterial pressure during the aortic crossclamp period while on cardiopulmonary bypass was usually treated by us with hypotensive drugs. We noticed, however, that aspirating shed excess pulmonary venous blood from the open pleural cavities causes an immediate reduction in mean arterial pressure, obviating the need for any further pharmaceutical intervention. In this study we investigated the relationship between the reduction in mean arterial pressure and the levels of prostacyclin and prostaglandin E2 in the peripheral and pulmonary venous blood. Ten men undergoing coronary bypass operations had 21 episodes of increased mean arterial pressure (106.9 +/- 11.4 mm Hg) during aortic crossclamping, which was reduced to 67.4 +/- 11.4 mm Hg (p less than 0.001) only by aspirating a mean of 490 ml (range 150 to 1100 ml) of pulmonary venous blood from the pleurae back into the circulation. Mean peripheral prostacyclin level, measured as 6-keto-prostaglandin F1 alpha, and prostaglandin E2 level, both measured by radioimmunoassay technique, were significantly lower at peak mean arterial pressure (419 +/- 180 and 59.5 +/- 21.2 pg/ml) than at lowest mean arterial pressure (632 +/- 271 and 96.7 +/- 52.4 pg/ml for 6-keto-prostaglandin F1 alpha and prostaglandin E2, respectively; p less than 0.001). Prostaglandin F1 alpha and prostaglandin E2 levels in the aspirated pulmonary venous blood were 2309 +/- 3098 pg/ml and 749 +/- 909 pg/ml, respectively. The hypotensive effect of shed pulmonary venous blood that is aspirated back from the pleurae into the circulation seems to be mediated by the high levels of prostacyclin and prostaglandin E2, both powerful vasodilators.

Endocrinology of oviposition in the tuatara (Sphenodon punctatus): I. Plasma steroids and prostaglandins during natural nesting

Plasma concentrations of estradiol, progesterone, prostaglandin (PG) E2 and PGF were measured during three stages of the natural nesting cycle of the tuatara (Sphenodon punctatus), a rare New Zealand reptile. Specifically, we tested whether nesting activity in this species is correlated with significant modifications in plasma concentrations of these hormones. Tuatara dig a nest over a period of several nights, oviposit a complete clutch on a single night, and then guard that nest for several nights. We observed no significant changes in mean plasma concentrations of estradiol or progesterone among the different stages of nesting. In contrast, PGE2 was elevated during nest digging and oviposition but declined significantly during nest guarding. Plasma PGF was elevated during nest digging, rose significantly during oviposition, and declined to basal levels during nest guarding. These data indicate that oviposition in reptiles is associated with elevated plasma concentrations of PGs, suggesting that these hormones function in causing oviducal contractions and/or luteolysis. Moreover, these data suggest that the role of PGs in oviducal function may have been conserved throughout evolution of the amniote vertebrates.