Effects of mild physical exercise on serum lipoproteins and metabolites of arachidonic acid: a controlled randomised trial in middle aged men

To study the effects of physical exercise on biochemical risk factors for ischaemic heart disease 31 healthy middle aged men undertook regular physical exercise for two months and 29 served as controls in a randomised trial. In the men taking regular exercise serum cholesterol concentrations increased 26% more in the high density lipoprotein subfraction two (HDL2) and decreased 31% more in the subfraction three (HDL3) and 9% more in the low density lipoprotein fraction than in the control group. A tendency towards increased plasma 6-keto-prostaglandin F1 alpha concentration and decreased serum thromboxane B2 concentration was found during the period of regular exercise, but prostaglandin E2 concentrations remained unchanged. The increase in plasma 6-keto-prostaglandin F1 alpha concentration was associated with an increase in serum HDL2 cholesterol concentration in the group taking regular exercise. Our data suggest that mild regular physical exercise favourably influences cholesterol distribution in serum lipoproteins in healthy middle aged men and may have beneficial effects on circulating metabolites of arachidonic acid.

Circulating endothelin-1 in obstructive sleep apnea

Endothelin (ET)-1 is a potent vasoconstrictive and mitogenic peptide produced by endothelial cells and degraded predominantly in pulmonary vasculature. We measured ET-1 in 9-normotensive and 14 hypertensive men with obstructive sleep apnea. The ET-1 levels were higher in both normotensive (mean +/- SD, 6.3 +/- 2.8 pg/ml) and hypertensive (7.8 +/- 3.0 pg/ml) groups than in 66 healthy controls (2.9 +/- 1.2 pg/ml). Ten patients were restudied after three months of nCPAP treatment. No decrease in ET-1 was observed.

A modified method for extraction and purification of prostaglandins with resin XAD-2

Non-ionic resins such as XAD-2 have been widely used as part of routine procedures in the gas chromatographic-mass spectrometric determinations of prostaglandins from aqueous solutions. However, there are reports that XAD-2 cannot be used in connection with radioimmunoassay (RIA), because the column constantly leaks a polymer which almost completely inhibits the antigen-antibody binding. It seems, however, possible to overcome these difficulties by modifying the procedure. The present method can be used with RIA and in combination with further chromatographic purifications for GC-MS determinations.

Effect of nasal CPAP treatment on plasma volume, aldosterone and 24-h blood pressure in obstructive sleep apnoea

Polycythaemia, peripheral oedema formation and hypertension have classically been described in association with obstructive sleep apnoea (OSA). However, there is very limited information about blood volume in OSA and how it changes during long-term treatment with nasal continuous positive airway pressure (nCPAP). Plasma (PV) and red-cell volumes (RCV), 24-h ambulatory blood pressure (BP), 24-h natriuresis and morning plasma aldosterone, renin activity and atrial natriuretic peptide in 11 men with a mean age of 47 y (range 37-55), apnoea index (AI) of 55 (22-106), body mass index of 36 (30-43) and seated BP of > or = 140/90 mmHg without any medication were measured. BP-measurements were repeated after 3 weeks and all measurements after 3 mo of nCPAP treatment. Aldosterone and 24-h mean heart rates decreased during treatment. Twenty-four-h BP decreased after 3 weeks but that decrease did not persist after 3 mo of treatment. There was a relationship between changes in night-time mean BP and PV and aldosterone. The haematocrit declined in every patient. No significant changes were found in the mean PV or RCV. They were in all instances lower than has earlier been described for normal, non-obese subjects. These data also suggest that OSA causes divergent individual disturbances in blood volume homeostasis which can be corrected by nCPAP.

Evening primrose oil and olive oil in treatment of rheumatoid arthritis

The effects of 10 ml of evening primrose oil or olive oil, administered twice daily for 12 weeks, on clinical and laboratory signs and on plasma prostaglandins were studied in 18 patients with rheumatoid arthritis. The plasma concentration of PGE2 decreased and that of TxB2 increased in both treatment groups, but no significant improvement could be seen in either group.

Effects of coffee and tea on lipoproteins and prostanoids

The effects of coffee and tea on serum lipoproteins, plasma and urinary prostanoids and thromboxane production by platelets were studied in 12 healthy volunteers aged 33-45 years. They consumed daily, during 3 successive periods of 3 weeks, 8 cups of either instant coffee (16 g/d), instant tea (2.8 g/d) or rosehip 'tea'. The daily dose of coffee yielded 520 mg caffeine, that of tea 200 mg caffeine, while no caffeine was detected in the rosehip 'tea'. No differences were observed between the study periods in the total serum or serum lipoprotein (VLDL, LDL, HDL2, HDL3) cholesterol or triglyceride concentrations. Plasma and serum concentrations and urinary excretion of prostanoids (plasma and urinary TXB2, PGE2 and 6-keto-PGF1 alpha and serum TXB2) remained constant during the three study periods. These results suggest that coffee or caffeine do not exert any detectable effects on serum lipids in healthy normolipidaemic individuals.

Breed differences in natriuretic peptides in healthy dogs

BACKGROUND

Measurement of plasma concentration of natriuretic peptides (NPs) is suggested to be of value in diagnosis of cardiac disease in dogs, but many factors other than cardiac status may influence their concentrations. Dog breed potentially is 1 such factor.

OBJECTIVE

To investigate breed variation in plasma concentrations of pro-atrial natriuretic peptide 31-67 (proANP 31-67) and N-terminal B-type natriuretic peptide (NT-proBNP) in healthy dogs.

ANIMALS

535 healthy, privately owned dogs of 9 breeds were examined at 5 centers as part of the European Union (EU) LUPA project.

METHODS

Absence of cardiovascular disease or other clinically relevant organ-related or systemic disease was ensured by thorough clinical investigation. Plasma concentrations of proANP 31-67 and NT-proBNP were measured by commercially available ELISA assays.

RESULTS

Overall significant breed differences were found in proANP 31-67 (P < .0001) and NT-proBNP (P < .0001) concentrations. Pair-wise comparisons between breeds differed in approximately 50% of comparisons for proANP 31-67 as well as NT-proBNP concentrations, both when including all centers and within each center. Interquartile range was large for many breeds, especially for NT-proBNP. Among included breeds, Labrador Retrievers and Newfoundlands had highest median NT-proBNP concentrations with concentrations 3 times as high as those of Dachshunds. German Shepherds and Cavalier King Charles Spaniels had the highest median proANP 31-67 concentrations, twice the median concentration in Doberman Pinschers.

CONCLUSIONS AND CLINICAL IMPORTANCE

Considerable interbreed variation in plasma NP concentrations was found in healthy dogs. Intrabreed variation was large in several breeds, especially for NT-proBNP. Additional studies are needed to establish breed-specific reference ranges.

Effects of antirheumatic drugs on leukotriene B4 and prostanoid synthesis in human polymorphonuclear leukocytes in vitro

The effects of D-penicillamine, sodium aurothiomalate, indomethacin, timegadine and tolfenamic acid on the lipoxygenase and cyclo-oxygenase pathways of arachidonic acid metabolism were studied in human polymorphonuclear leukocytes (PMNs) in vitro. In short-term incubations, D-penicillamine and aurothiomalate did not affect leukotriene B4 (LTB4), prostaglandin E2 (PGE2) or thromboxane B2 (TXB2) production. Each of the three non-steroidal anti-inflammatory drugs (NSAIDs) used were potent inhibitors of prostanoid synthesis. In higher concentrations they also reduced LTB4 production; timegadine and tolfenamic acid were effective in concentrations comparable to those measured in plasma during drug therapy, whereas indomethacin was needed in ten times higher concentrations. The different effects of NSAIDs on 5-lipoxygenase activity may be of importance in their therapeutic actions as well as in the appearance of some side-effects, e.g. gastric irritation and "aspirin-induced" asthma.

Exercise-induced increase in plasma arachidonic acid and thromboxane B2 in healthy men: effect of beta-adrenergic blockade

We examined the effects of beta-blockade with the nonselective antagonist propranolol, the cardioselective antagonist atenolol, and the cardioselective antagonist with partial agonist activity, practolol, on the levels of free arachidonic acid (AA), thromboxane B2 (TxB2), prostaglandin (PG) E2, and 6-keto-PGF1 alpha in plasma, and TxB2 production by platelets during clotting in six normal subjects during submaximal dynamic exercise. The drugs were given intravenously in equipotent increasing doses before the exercise test. Exercise induced a clear increase in AA, TxB2, and 6-keto-PGF1 alpha in plasma. During the first 60 min of exercise all three beta-blockers decreased the plasma levels of AA and TxB2. Propranolol (0.19 mg/kg) was slightly more effective than atenolol (0.19 mg/kg) or practolol (0.64 mg/kg); however, at exhaustion, propranolol was markedly more effective than the other two blockers. Plasma 6-keto-PGF1 alpha and PGE2 levels were less affected by beta-blockade during exercise, and no significant effect was seen on TxB2 formation by platelets. The plasma 6-keto-PGF1 alpha/TxB2 ratio was markedly higher after propranolol treatment than after treatment with the other two blockers during the exercise period. These results suggest that the capability of a nonselective blocker to inhibit both beta 1- and beta 2-adrenergic receptors may be of advantage because of the more effective inhibition of thromboxane formation than with a cardioselective blocker, especially when the sympathetic tone is markedly increased.

Comparison of the effects of different anti-inflammatory drugs on synovial fluid prostanoid concentrations in patients with rheumatoid arthritis

The effects of one-day treatment with nine nonsteroidal anti-inflammatory drugs and prednisolone on human synovial fluid concentrations of prostanoids were studied. The doses were calculated so as to be approximately equipotent according to clinical experience and the recommendations of the manufacturers. Most of the drugs used reduced clearly PGE2 and TxB2 levels in synovial fluid, but only a slight diminution in 6-keto-PGF1 alpha values was found. Carprofen, diclofenac, indomethacin, naproxen and tolfenamic acid reduced significantly the synovial fluid PGE2 concentrations. Diclofenac and indomethacin also reduced significantly the synovial TxB2 concentrations.

Adrenaline infusion evokes increased thromboxane B2 production by platelets in healthy men: the effect of beta-adrenoceptor blockade

The effects of direct adrenergic stimulation, achieved by 60-min adrenaline infusion (0.1-0.2 microgram kg-1 min-1), on thromboxane B2 (TxB2) production by platelets in whole blood ex vivo and on ADP-induced platelet aggregation were studied in seven healthy male volunteers. The effects of two beta-adrenergic blocking agents, pindolol and practolol, on the adrenaline-induced changes were furthermore analyzed. Adrenaline administration resulted in an about ten-fold elevation in plasma adrenaline, and an about three-fold increase in TxB2 production by platelets at 30 min of infusion. The increased TxB2 production persisted throughout the entire adrenaline infusion, and up to 30 min of postinfusion period (recovery). Pindolol blunted markedly the effects of adrenaline on platelet TxB2 production, whereas practolol seemed to have only a weak effect. The sensitivity of platelets to ADP-induced aggregation did not change during the 60 min of adrenaline infusion. However, at 60 min of recovery the platelets showed a significantly increased sensitivity to ADP. Correspondingly, pindolol treatment did not affect platelet sensitivity during the infusion period, but at 60 min of recovery it had caused a significantly decreased sensitivity of platelets to ADP-stimulation. Plasma-free fatty acids increased markedly during the adrenaline infusion. This increase was totally blocked by pindolol, but only partly by practolol. The present results demonstrate that adrenaline, at plasma levels seen for example, in complicated myocardial infarction, stimulates platelet TxB2 production and increases the sensitivity of platelets to ADP after the infusion. Pindolol, but not practolol, inhibits these adrenaline-induced changes in platelet behaviour.

Effects of non-steroidal anti-inflammatory drugs and prednisolone on synovial fluid white cells, prostaglandin E2, leukotriene B4 and cyclic AMP in patients with rheumatoid arthritis

Altogether 53 patients (31 women, 22 men) with definite rheumatoid arthritis were randomly divided into groups of 5-6 patients and treated for one day only with one of the following non-steroidal anti-inflammatory drugs (NSAIDs): acetylsalicylic acid, carprofen, diclofenac, indomethacin, naproxen, proquazone, timegadine, tolfenamic acid or paracetamol, and with prednisolone, in recommended doses. Synovial fluid samples were collected before and after the treatment. White cell count and its differentiation as well as the concentrations of protein, cyclic adenosine-3',5'-monophosphate (cAMP), prostaglandin E2 (PGE2) and leukotriene B4 (LTB4) were measured from the synovial fluid. Synovial fluid leukocyte counts correlated with PGE2 concentrations, but showed no correlation with LTB4 levels before treatment. Significant changes were seen in the form of lowered PGE2 values following treatment with the clinically and experimentally most potent NSAIDs, and as depressed LTB4 levels following prednisolone treatment. The other markers of inflammation are obviously more resistant, changing only slowly during prolonged treatment, and may thus be, at least in part, secondary to the changes in prostanoids.

Kinetics of chlorambucil in vitro: effects of fluid matrix, human gastric juice, plasma proteins and red cells

The mechanisms involved in the bioavailability of chlorambucil or 4-[p-(bis[2-hydroxyethyl]amino)phenyl]-butyric acid are poorly understood. The effects of different matrices on the disintegration of chlorambucil were investigated by HPLC, 1H NMR, 31P NMR, and mass spectrometry. Cellular incorporation and protein binding of the drug in vitro was assessed with [3H]-chlorambucil. Decomposition of chlorambucil and its major metabolite, phenylacetic acid mustard, to mono- and dihydroxy derivatives, was significantly faster in water than in PBS, (phosphate-buffered saline, pH 7.4). The hydrolysis of chlorambucil was as fast in plasma ultrafiltrate as in PBS; plasma proteins, preferentially albumin, prevented this disintegration. In phosphate-buffered media, two additional stabile hydrolysis products were found which were characterised as the mono- and bis-phosphates of 4-[p-(bis[2-hydroxyethyl]amino)phenyl]butyric acid, results of the reaction of nucleophilic buffer species with the aziridinium ion intermediates. Chlorambucil bound covalently to plasma proteins and was incorporated into red cells. These interactions are likely to have a significant role in vivo, reducing the bioavailability of the drug. High H+ concentration associated with high chloride concentration in human gastric juice had a stabilizing effect on chlorambucil. Incorporation of [3H]-chlorambucil into red cells was inhibited in a concentration-dependent fashion by whole human plasma as well as by albumin. We conclude that the chemico-biological interactions demonstrated in the present investigation provide explanations for the remarkable pharmacokinetic differences observed intra- and inter-individually in the clinical use of chlorambucil. The present information is important, when clinical or in vitro evaluation of efficacy and bioavailability of chlorambucil is considered.

Divergent effects of atenolol, practolol and propranolol on the peripheral metabolic changes induced by dynamic exercise in healthy men

A study has been made of the effects of intravenous atenolol, practolol and propranolol on the changes induced by exhaustive dynamic physical exercise in blood pressure, heart rate and blood levels of lactate, glucose, insulin, free fatty acids and potassium. The mean endurance of dynamic exercise was reduced by all three beta-blockers, most markedly by propranolol. After all the beta-blockers heart rate showed a similar decrease during the first 60 min of exercise; atenolol caused the smallest reduction at exhaustion. All three beta-blockers lowered the systolic blood pressure during exercise; propranolol was the most active agent both during exercise and during recovery. The diastolic pressure was higher during exercise after treatment with the beta-blockers, especially propranolol. The beta-blockers did not markedly affect the elevation of blood lactate induced by exercise. The increase in blood glucose was abolished by atenolol. Plasma insulin was reduced by exercise after beta-blockade, most markedly after propranolol and practolol. All the beta-blockers were equipotent in reducing up to 60 min the exercise-induced increase in plasma free fatty acids, although at exhaustion propranolol had a significantly greater effect than atenolol or practolol. Serum potassium was higher after propranolol and atenolol than after practolol during exercise and recovery.

Inhibition of prostaglandin synthesis by indomethacin interacts with the antihypertensive effect of atenolol

The interaction of inhibition of prostaglandin (PG) synthesis by indomethacin (75 mg/day) with the antihypertensive effect of atenolol (50 mg b.i.d.) was studied in 11 untreated otherwise healthy men 35 to 45 years old with essential hypertension. Atenolol for 3 weeks decreased supine blood pressure (BP) from 157/109 mm Hg during placebo to 148/97 mm Hg. Indomethacin alone for 1 week slightly increased BP and antagonized the antihypertensive action of atenolol. Atenolol reduced plasma renin activity (PRA) to 40% but did not modify either the urinary excretion of vasodilatory PGs (PGE2 and prostacyclin measured as 6-keto-PGF1 alpha) or plasma kininogen and urine kallikrein. Indomethacin suppressed PRA to 27% and PG excretion to approximately 70% but did not markedly change plasma kininogen and urine kallikrein excretion. The decreased excretion of 6-keto-PGF1 alpha, the metabolite of the main vasodilatory prostanoid prostacyclin, correlated with the increased BP measured in standing subjects. The effects of indomethacin were practically the same when given with atenolol as when given alone. We conclude that the slight increase in BP by indomethacin in essential hypertension is associated with the reduced production of vasodilatory PGs but not with alterations in activities of the renin-angiotensin or kallikrein-kinin systems.

Differences in the production of arachidonic acid metabolites between healthy and rheumatic synovial fibroblasts in vitro. A preliminary study

Production of various arachidonic acid metabolites from both endogenous and exogenous substrate was measured using cultures of synovial fibroblasts from healthy and rheumatic synovia. At first, the rheumatic cells showed retarded growth and an altered histological picture. Rheumatic cells produced more 6-keto-PGF1 alpha, the main metabolite of prostacyclin, and prostaglandin E2 than did normal cells, which synthesized more thromboxane B2. Later on these differences diminished or disappeared, except regarding 6-keto-PGF1 alpha. When fairly high concentrations of exogenous arachidonic acid were used, for 2-hour incubation of the cells, the production of identified metabolites, 6-keto-PGF1 alpha, PGF2 alpha, PGE2, PGD2, PGA + PGB and thromboxane B2, was slightly less in rheumatic cells. In general, the main metabolite formed was 6-keto-PGF1 alpha. Some kind of feedback mechanism between prostaglandins and cyclic nucleotides is suggested.

Effects of a prostacyclin analog iloprost on kidney function, renin-angiotensin and kallikrein-kinin systems, prostanoids and catecholamines in man

Iloprost (ZK 36 374), a stable analog of carbaprostacyclin, was infused for 72 h to nine patients with advanced obliterative arterial disease. Iloprost caused a marked vasodilation and a compensatory increase in cardiac output. The glomerular filtration rate increased by 45% and tubular reabsorption of sodium and water were reduced by 80% and 107%, respectively. The urine excretion rate increased by 122%. Tubular handling of potassium and calcium were not influenced by iloprost but magnesium reabsorption was stimulated. The renin-angiotensin system was not activated while serum angiotensin converting enzyme activity was decreased. Kallikrein excretion in urine was increased 4.4-fold but plasma kininogen, a substrate for kallikrein in producing vasoactive kinins, was unaffected by the drug. Plasma levels of 6-keto-PGF1 alpha and TxB2 were decreased and their excretion in urine increased. Plasma catecholamines were not changed by iloprost. Several of the changes persisted for at least the first postinfusion day. The results indicate that iloprost increases urine excretion rate by increasing glomerular blood flow and by inhibiting sodium and water reabsorptions. The kinin-forming system, but not the renin-angiotensin system or plasma catecholamines, may be activated. The decrease in plasma level of prostanoids can be, at least partly, due to their increased excretions in urine.

The effect of pindolol on exercise-induced increase in plasma vasoactive prostanoids and catecholamines in healthy men

The effect of intravenous pindolol (0.0256 mg/kg) on changes in plasma arachidonic acid (AA), some of its metabolites, and catecholamines induced by submaximal exercise was studied in six healthy male volunteers. Exercise resulted in markedly increased plasma concentrations of thromboxane B2 (TxB2) from 0.13 +/- 0.01 to 0.27 +/- 0.02 pmol/ml (mean +/- SEM; p less than 0.05) and AA from 4.1 +/- 0.6 to 8.0 +/- 0.9 mumol/l (p less than 0.005). No significant changes were seen in plasma concentrations of 6-keto-PGF1 alpha or PGE2 during exercise. A marked increase in plasma noradrenaline was seen already at 15 min of exercise, while the adrenaline concentration increased significantly at 30 min of exercise and a very marked increase in the adrenaline concentration was seen at exhaustion. A positive correlation (r = 0.54; p less than 0.05) was seen between plasma TxB2 and plasma adrenaline during exercise. The peak increase in both of these parameters was seen simultaneously at exhaustion. Pindolol treatment resulted in almost total inhibition of the increase in plasma TxB2 and AA during exercise. Pindolol treatment also resulted in a significantly higher adrenaline level at exhaustion. These data seem to indicate that an increased sympathetic tone may result in an increased release of arachidonic acid in the formation of vasoconstrictive thromboxane A2.

Fatty acid composition and arachidonic acid metabolites in ascitic fluid of patients with ovarian cancer

Fatty acid composition and arachidonic acid metabolites in ascitic fluids of patients with ovarian cancer were compared to those in the peritoneal fluids of patients with benign gynecologic conditions. Substantial amounts of PGE2, PGF2 alpha, TXB2, and leukotriene B4 were detected in the fluids of the both patient groups. In the group of the cancer patients the concentrations of TXB2 were slightly smaller than those in the control group. In the percentage amounts of the eicosanoid precursor fatty acids there could not be detected differences between these two groups. However, in the peritoneal fluids of the cancer patients the percentage amount of palmitoleic acid (16:1) was significantly higher than that in the control group.

Effects of noradrenaline and dopamine infusions on arachidonic acid metabolism in man

We infused noradrenaline (0.025 micrograms/kg/min for 60 min, n=7) and dopamine (3.0 micrograms/kg/min for 60 min, n=6) into healthy male volunteers to study the effects of these catecholamines on in vivo thromboxane A2, prostacyclin and leukotriene E4 production measured as urinary excretions of 11-dehydro-thromboxane (TX) B2, 2,3-dinor-6-keto-prostaglandin (PG) F1alpha and leukotriene (LT) E4, respectively. Plasma noradrenaline and dopamine concentrations were 2.9+/-0.3 and 233+/-17 nmol/l at the endo fo the noradrenaline and dopamine infusions, respectively. Noradrenaline decreased thromboxane production and increased leukotriene production almost two fold. It had hardly any effect on prostacyclin production. Dopamine had no significant effects on any of the variables, however, it had a tendency to increase prostacyclin and leukotriene production. The results indicate that noradrenaline is a more important modulator of arachidonic acid metabolism than dopamine in vivo.

Pharmacokinetics of chlorambucil in patients with chronic lymphocytic leukaemia: comparison of different days, cycles and doses

The effects of repeated treatment cycles and different doses on intraindividual variation in oral bioavailability of chlorambucil and its first, active, and more toxic metabolite, phenylacetic acid mustard, were studied. Chlorambucil and phenylacetic acid mustard concentrations were measured with HPLC on Day 1 and on Day 4 in 15 timed blood samples from 11 chronic lymphocytic leukaemia patients receiving chlorambucil therapy cycles. Bioavailability was evaluated also after the first chlorambucil doses of six consecutive treatment cycles repeated every 4 weeks with increasing chlorambucil doses starting with 0.8 mg/kg/4 days, and increased by 0.1 mg/kg/4 days cycle. Area under the concentration-time-curve (AUC) from t=0 to infinite was in average 3.2 hr* microg/ml for the first cycle, and decreased by 17% in four days (P<0.05). The mean distribution half-life of chlorambucil was 0.49 hr and the terminal elimination half-life 2.45 hr. The bioavailability of chlorambucil decreased further when 4-day treatment cycles were repeated. For the fifth cycle, dose-corrected AUC for the first 2 hr was 33% smaller than that for the first cycle (P for trend <0.01). Data suggest accelerated metabolism and elimination of chlorambucil and phenylacetic acid mustard, but reduced oral bioavailability of chlorambucil cannot be excluded. However, except for AUC, none of the pharmacokinetic parameters of chlorambucil changed significantly during the first 4-day treatment period. The maximal plasma concentration and AUC of phenylacetic acid mustard did not change significantly during repeated treatment cycles. According to this trial a dose adjustment of chlorambucil is not necessary during a short-term course, but may be necessary when treatment cycles are repeated. An average increase in the chlorambucil dose of 10% per cycle maintains similar plasma concentration of chlorambucil.

Effect of Breed on Plasma Endothelin-1 Concentration, Plasma Renin Activity, and Serum Cortisol Concentration in Healthy Dogs

BACKGROUND

There are breed differences in several blood variables in healthy dogs.

OBJECTIVE

Investigate breed variation in plasma endothelin-1 (ET-1) concentration, plasma renin activity, and serum cortisol concentration.

ANIMALS

Five-hundred and thirty-one healthy dogs of 9 breeds examined at 5 centers (2-4 breeds/center).

METHODS

Prospective observational study. Circulating concentrations of ET-1 and cortisol, and renin activity, were measured using commercially available assays. Absence of organ-related or systemic disease was ensured by thorough clinical investigations, including blood pressure measurement, echocardiography, ECG, blood and urine analysis.

RESULTS

Median ET-1 concentration was 1.29 (interquartile range [IQR], 0.97-1.82) pg/mL, median cortisol concentration 46.0 (IQR, 29.0-80.8) nmol/L, and median renin activity 0.73 (IQR, 0.48-1.10) ng/mL/h in all dogs. Overall, breed differences were found in ET-1 and cortisol concentrations, and renin activity (P < .0001 for all). Pair-wise comparisons between breeds differed in 67% of comparisons for ET-1, 22% for cortisol, and 19% for renin activity, respectively. Within centers, breed differences were found at 5/5 centers for ET-1, 4/5 centers for cortisol, and 2/5 centers for renin activity. Newfoundlands had highest median ET-1 concentration, 3 times higher than Cavalier King Charles Spaniels, Doberman Pinschers, and Dachshunds. Median renin activity was highest in Dachshunds, twice the median value in Newfoundlands and Boxers. Median cortisol concentration was highest in Finnish Lapphunds, almost 3 times higher than in Boxers.

CONCLUSIONS AND CLINICAL IMPORTANCE

Breed variation might be important to take into consideration when interpreting test results in clinical studies.

Differences in prostanoid production between healthy and rheumatic synovia in vitro

To evaluate further the complex role of prostanoids in rheumatoid arthritis we compared the immunoreactive prostanoid production of healthy and rheumatic synovial cells in a primary cell culture. During the first days in culture the adherent cells from rheumatic synovia produced higher amounts of prostanoids, especially the proinflammatory and immunosuppressive prostaglandin E2 (PGE2), than cells originating from non-inflamed synovia. This difference disappeared within one week culture and was partly explained by altered substrate availability.

Effects of halothane and enflurane on prostanoid concentrations in operation patients

Prostanoid formation may be stimulated by different events associated with anaesthesia and operation, such as positive pressure ventilation and tissue trauma. We investigated the effects of halothane and enflurane on plasma and serum prostanoid concentrations in 19 patients scheduled for minor operations. In 9 abdominal surgery patients, thromboxane B2 concentrations were followed up to the fifth postoperative day. Prostanoid determinations were carried out with RIA. In general, the changes in prostanoid concentrations in patients anaesthetised with halothane or enflurane were similar. During spontaneous breathing there was a decrease in plasma PGE2 and TxB2 concentrations. During intermittent positive pressure ventilation and operation, PGE2 and TxB2 concentrations rose but 6-keto-PGF1 alpha did not. After operation, TxB2 concentrations remained elevated but the other prostanoids returned to preoperative values. TxB2 concentrations decreased to the preoperative level on the first postoperative day. The elevated TxB2 concentrations during and after surgery can be regarded, in some patients, as a potential risk factor for cardiovascular and thromboembolic complications.