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Platelet aggregation test was used for PGI2 measurements. The use of 6 % CO2 in air stabilized human platelet rich plasma (PRP) so that it could be used for up to 7 hours in these measurements. The PGI2 caused inhibition of aggregation in response to ADP was concentration dependent in the range of 0.5 ng/ml to 50 ng/ml. Isolated perfused rat lungs released spontaneously 190 ng/min PGI2 and about 3 % of infused arachidonic acid potassium salt (equivalent to 25 microgram/min arachidonic acid) was converted to PGI2.

A single exposure to cigarette smoke for one hour decreased the pulmonary microsomal epoxide hydratase activity in rats. A more rapid decrease was seen after 5 consecutive exposures, one hour daily. Meanwhile, the activity of pulmonary aryl hydrocarbon hydroxylase (AHH) increased several fold. In small intestinal mucosa the activities of AHH and epoxide hydratase were enhanced both by single and repeated cigarette smoke-exposures. In kidney the activity of AHH increased, whereas neither that of epoxide hydratase nor of UDP glucuronosyltransferase changed. In small intestinal mucosa the activity of UDP glucuronosyltransferase increased after repeated smoke-exposures, but in lung no clear change in the UDP glucuronosyltransferase activity was detected.

The metabolism of prostaglandin E2 (PGE2) is decreased by dipyridamole (20 microM) in rat isolated perfused lungs. The inhibition of the metabolism is reversible as the decreased metabolism returned to the control level when pulmonary infusion of dipyridamole was abolished. After pulmonary injection of 14C-PGE2 (10 nmol) the radioactivity appeared more rapidly in the effluent when dipyridamole was infused into pulmonary circulation. Dipyridamole in vitro did not change the activity of 15-hydroxyprostaglandin dehydrogenase (15-OH-PGDH) in the 100,000 x g supernatant fraction of homogenized lungs. Thus, the decreased metabolism seems to be due to the inhibition of the uptake of PGE2 into the lungs. When the rats were pretreated with dipyridamole in drinking water for one week the activity of 15-OH-PGDH in the 100,000 x g supernatant fraction of the lungs was not changed significantly.

Human polymorphonuclear leukocytes (PMNL) were incubated for 60 min at 37 degrees C with 20 microM or 100 microM prednisolone, and stimulated thereafter for 1 min with 10 nM LTB4, 10 nM LTC4, 10 nM LTD4 or 10 microM histamine. The amount of thromboxane B2 (TXB2) formed by PMNLs was measured by radioimmunoassay. PMNLs spontaneously released TXB2 during 60 min incubation, and the rate of formation was significantly reduced in the presence of 20 microM or 100 microM prednisolone. LTB4, LTC4, LTD4, and histamine stimulated the rate of TXB2 production during 1 min incubation to 93-, 49-, 60-, and 55-fold, respectively. Preincubation with prednisolone for 60 min had a slight inhibitory effect on the stimulated TXB2 formation but TXB2 production still remained many fold as compared to its spontaneous rate of formation. The present study indicates that human PMNLs are capable of synthetizing TXB2, and its spontaneous rate of formation is inhibited by a synthetic glucocorticoid, prednisolone. The great stimulatory effect of LTB4, LTC4, LTD4, and histamine suggests that these agents may activate phospholipases or other acylhydrolases which liberate arachidonate for eicosanoid biosynthesis.

Cardiovascular diseases among Greenland Eskimos are rare because their diet is rich in fatty fish and marine mammals. The beneficial effect of the fish diet appears to be mediated, at least in part, by the high amount of eicosapentaenoic acid in fish. We investigated the total lipid amount and fatty acid composition of 12 commonly eaten North-European fish species. Most of the detected fatty acids were unsaturated, and the content of eicosapentaenoic acid varied usually between 6 and 16%. The amount of total lipid varied between 3.5 and 216 mg/g wet tissue. The total amount of lipid in different fish species seems to be more important than the respective fatty acid composition when considering which fish should be especially beneficial in the diet. Herring, salmon, Baltic herring, turbot and trout seem to contain most abundantly eicosapentaenoic acid.

Following the injection of 14C-arachidonic acid (4.1 nmol) into hamster isolated lungs about 80% of the administered radioactivity was retained by the lungs. During subsequent perfusion only a small amount of radioactivity was released to the perfusion effluent. This release was not affected by pulmonary infusion of prednisolone at 20 microM or 100 microM. In control lungs 84 +/- 1% (+/- SEM) of the retained radioactivity was recovered in the phospholipid, 13 +/- 1% in the neutral lipid and 3 +/- 1 in the free fatty acid fraction. Pulmonary infusion of prednisolone increased the amount of radiolabel in the neutral lipids. This was due to the increased amount of 14C-arachidonic acid in triacylglycerols. Prednisolone had no significant effects on the amount of 14C-arachidonate in diacylglycerols or in different phospholipids. Neither was the amount of free 14C-arachidonate in the lungs changed by prednisolone. The present study indicates that the release of arachidonic acid from triacylglycerols may be inhibited by prednisolone in hamster lungs.

The activity of aryl hydrocarbon hydroxylase (substrate: benzo(a)pyrene) was increased in the tracheas of rats exposed to cigarette smoke for 1 h daily for either 1 or 10 days. However the degree of increase in activity was lower in the trachea than in the lung. After a single exposure, activity in the trachea was at its highest level 12 h following exposure (3.2-fold compared to the control), but had returned to the control level within 24 h. Also, the amounts of covalently bound metabolites of benzo(a)pyrene were increased (2-fold) in nucleic acid and protein fractions of the trachea, when the rats were killed 12 h after a single cirgarette smoke exposure. No significant changes in activity of epoxide hydratase (substrate: styrene oxide) could be detected in the trachea. After repeated exposures the activity of UDP-glucuronosyltransferase (substrate: methylumbelliferone) was increased (1.7-fold) in the trachea.

The effects of smoke from low-, medium- and high-tar cigarette brands on the metabolism of prostaglandin E2(PGE2) were investigated in isolated rat lungs. When isolated lungs were ventilated with smoke of high- or medium-tar cigarettes during an infusion of PGE2 into the pulmonary circulation, the amount of unmetabolized PGE2 was increased and that of 15-ketometabolites (15-keto-PGE2 and 13,14-dihydro-15-keto-PGE2 together) was decreased in the perfusion effluent compared to air ventilated control lungs. This decrease in the pulmonary metabolism of PGE2 was seen by both filter and non-filter high/medium-tar cigarettes. When isolated rat lungs were ventilated with smoke of low-tar cigarettes no change in the metabolism of PGE2 was detected. The pressor response of the vascular bed to the infusion of PGE2 was inhibited with smoke of both low- and high-tar cigarettes.

Addition of arachidonic acid to human platelet rich plasma caused a reversible aggregation, which was greatly decreased after aspirin ingestion. ADP induced a greater aggregation, which was only slightly decreased after aspirin ingestion. When PRP was incubated with arachidonic acid for 2 or 6 min before the addition of ADP, the ADP-induced aggregation was greatly decreased. This decrease was not changed by aspirin ingestion. The present study indicates that arachidonic acid is metabolized in human platelets not only to aggregatory compounds but also to anti-aggregatory compound(s). The formation of the latter compound is not inhibited by aspirin.

Cigarette smoke ventilation of isolated perfused rat lungs partially inhibited the pulmonary vascular pressor response to arachidonic acid. The amounts of metabolites of exogenous arachidonic acid in the perfusion effluent remained unchanged during smoke ventilation. The antiaggregatory effect of the effluent during pulmonary infusion of AA was not decreased by smoke ventilation. The cause of the previously reported increased platelet aggregation after smoking remains unclear.

The metabolism of prostaglandin E2 (PGE2) was decreased in isolated male hamster lungs, when sulfinpyrazone was infused into the pulmonary circulation. After pulmonary injection of 20 nmol of 14C-PGE2 the amount of 15-keto-metabolites of PGE2 was in the effluent from control lungs 4.0 +/- 0.5 nmol (mean +/- SEM) and in those from 20 mu M and 100 mu M sulfinpyrazone treated lungs 1.9 +/- 0.2 nmol (2P Less Than 0.01 compared to the control) and 1.7 +/- 0.4 nmol (2P Less Than 0.01), respectively. The amount of unmetabolized PGE2 was correspondingly increased in the effluent by sulfinpyrazone. The rate of efflux of the radioactivity from the lungs was increased by sulfinpyrazone. After injection of 10 nmol of 14C-PGE2 into the pulmonary circulation half of the injected radioactivity appeared in the effluent in 30 +/- 4 sec in control and in 15 +/- 0.7 sec (2P Less Than 0.01) in 20 mu M sulfinpyrazone experiments. Sulfinpyrazone had no effect on the activity of 15-hydroxyprostaglandin dehydrogenase in the 100.000 g supernatant fraction of homogenized hamster lungs. Thus the decreased metabolism of PGE2 in the pulmonary circulation of hamster lungs is obviously not due to the inhibition of 15-hydroxyprostaglandin dehydrogenase. A more likely explanation seems to be the decreased uptake of PGE2 into the lung cells.

The effects of aspirin and dipyridamole on the metabolism of exogenous 14C-arachidonic acid were investigated in intact human platelets in vitro. The formation of thromboxane B2 (TXB2) and 12-hydroxy-5,8,10-heptadecatrienoic acid (HHT) was inhibited dose dependently by aspirin but not by dipyridamole. Neither was the aspirin caused inhibition in TXB2 and HHT formation modified by dipyridamole. At high concentrations aspirin caused a slight increase in the amount of 12-hydroperoxy-5,8,10,14-eicosatetraenoic acid (12-HPETE) and a corresponding decrease in that of 12-hydroxy-5,8,10,14-eicosatetraenoic acid (12-HETE). This was seen also when aspirin was combined with dipyridamole. At high concentrations (100 microM and 1 mM) dipyridamole caused an increased formation of 12-HETE and an unidentified metabolite group. The present study indicates that dipyridamole has no effect on the formation of the cyclo-oxygenase metabolites in human platelets but the lipoxygenase pathway seems to be stimulated by dipyridamole.

The synthesis of prostacyclin (PGI2) was studied in isolated perfused rat lungs during the infusion of radiographic contrast media into the pulmonary circulation. At the same molar concentration, diatrizoate, iopamidol, and NaCl fairly equally stimulated the generation of PGI2. A bolus injection of histamine also enhanced the formation of PGI2. A high dose of ionic diatrizoate and hypertonic saline (0.4 mol/l) caused considerable pulmonary edema, which was less marked with non-ionic iopamidol. Experiments with 125I-labeled contrast media indicated rapid efflux of contrast media from the lungs. The present investigation indicates that different contrast media stimulate the synthesis of prostacyclin mainly because of chemical irritation of the pulmonary endothelium. The enhanced formation of endothelium-derived prostacyclin may mediate some systemic and local side effects seen temporarily during intravascular contrast medium examinations.

The synthesis of prostaglandins and other metabolic products of arachidonic acid (AA) was investigated in isolated perfused lungs of hamsters during the infusion of various concentrations of meglumine diatrizoate and iopamidol. Forty nmol of 14C-AA was infused into the pulmonary circulation with radiographic contrast media (RCM), and prostaglandins, thromboxanes, and metabolites of lipoxygenases were analyzed from the nonrecirculating perfusion effluent. Arachidonate infusion increased the perfusion pressure. This pressor response was decreased by iopamidol but was not changed by diatrizoate. The amount of radioactivity was decreased in the perfusion effluent and increased in lung lipids by iopamidol. Meglumine diatrizoate increased radioactivity in the effluent with minimal effects on the distribution of radioactivity in lung lipids. Almost all arachidonate metabolites were decreased significantly by iopamidol when compared with hypertonic saline whereas diatrizoate caused an increasing trend in the formation of the metabolites of AA. The present study shows that ionic and nonionic RCM have different effects on the metabolism of arachidonic acid.

3H-TxB2 was infused into the pulmonary circulation of isolated perfused rat lungs. The metabolites were analysed from the nonrecirculating perfusion effluent. When the lungs were ventilated with cigarette smoke the amount of unmetabolized TxB2 in the effluent was increased by 50%. The amount of the main metabolite was, however, not changed. The efflux of radioactivity from the lungs after a bolus injection of 3H-TxB2 was slower during cigarette smoke ventilation than during air ventilation. This suggests that cigarette smoke inhibits the enzymes metabolizing TxB2 rather than the pulmonary thromboxane uptake system.

When 50 nmol of 14C-arachidonate was injected into the pulmonary circulation of isolated hamster lungs, the perfusion pressure was increased. This increase was not changed when sulfinpyrazone was infused into the pulmonary circulation at 20 mumol/l. Neither was the total amount of radioactivity in the effluent changed by sulfinpyrazone. The metabolites of arachidonic acid were analyzed from the nonrecirculating perfusion effluent, which was extracted with ethyl acetate first at neutral pH and then at pH 3.5. The only significant change in the metabolite formation was a small decrease in the amount of one metabolite extracted at neutral pH (obviously 12-hydroxy-5,8,10-heptadecatrienoic acid). The amounts of other metabolites, including 6-keto-PGF1 alpha, PGF2 alpha, PGE2 and TxB2 were unchanged. The present study indicates that the pulmonary metabolism of arachidonic acid is changed only slightly by sulfinpyrazone.

The interference of sodium salicylate with the effects of acetylsalicylic acid (ASA, aspirin) and indomethacin on arachidonic acid-induced platelet aggregation and thromboxane formation was studied in human platelet rich plasma. ASA and indomethacin suppressed both aggregation and the concomitant formation of thromboxane B2 whereas sodium salicylate alone had no significant effect on these parameters of platelet function. It did, however, partially prevent the inhibitory effects of ASA and indomethacin on platelet aggregation when it was added to platelet rich plasma before ASA or indomethacin. The inhibition of thromboxane formation by indomethacin was also prevented by sodium salicylate. When sodium salicylate was added to platelet rich plasma after ASA or indomethacin it did not modify the effects of these drugs. The present study indicates that sodium salicylate interferes with the effects of ASA and indomethacin on human platelet cyclo-oxygenase in vitro.

Isolated perfused rat lungs liberated fatty acids at a rate of 15 mumol/hr during perfusion of triglyceride-rich medium through the pulmonary vascular bed. About 80% of this activity seemed to result from lipoprotein lipase and 20% to hormone-sensitive lipase. Ventilation of the lungs with cigarette smoke instead of air during the perfusion reduced fatty acid liberation by 23%. Pre-exposure of rats to cigarette smoke for either 1 or 10 days did not cause significant changes in lung lipolytic activity compared to sham-exposed controls.

When human polymorphonuclear leukocytes (PMNL) were incubated with exogenous 14C-arachidonic acid (14C-AA), both lipoxygenase and cyclo-oxygenase metabolites were detected. The amount of the 5-lipoxygenase metabolites formed, including 5-hydroxy-6,8,11,14-eicosatetraenoic acid (5-HETE), was small. The amount of other mono-HETE's (migrating in the vicinity of 12-HETE) was greater, but this was obviously mainly due to the small amount of contaminating platelets. In the presence of calcium ionophore A23187 the rate of formation of 5-HETE was increased, but the formation of other metabolites remained unchanged. When PMNL were incubated with aspirin in the presence of A23187 the formation of the cyclo-oxygenase products was decreased but that of 5-HETE was unchanged. The present study indicates that the calcium ionophore A23187 stimulates specifically the 5-lipoxygenase in human PMNL and that aspirin has no effect on the formation of the 5-lipoxygenase metabolites of arachidonic acid in human PMNL.

The effects of nicotine and carbon monoxide on the production of PGI2 by rat arterial rings were studied. For PGI2 analysis, we used a bioassay based on platelet-rich plasma aggregation with ADP. Neither nicotine in the incubate nor pretreatment with carbon monoxide decreased PGI2-production as detectable in this bioassay system. Also, neither had a direct effect on the ADP-induced aggregability of human platelet-rich plasma. Consequently, these agents do not seem to be responsible for the temporary increase in platelet aggregability after cigarette smoking.

The metabolism and covalent binding of intratracheally instilled 7-3H-styrene oxide in the isolated perfused lungs of control and cigarette smoke-exposed rats were investigated. After intratracheal instillation of 100 nmoles of 7-3H-styrene oxide the lungs were perfused for 16 min and the nonrecirculating perfusate was collected in two fractions: 0--8 min and 8--16 min. About 40 percent of the instilled dose was in the 0--8 min perfusion medium, mainly in the form of unmetabolized styrene oxide. However, the radioactivity in the 8--16 min perfusion medium and lung tissue itself was mainly in the form of water soluble metabolites, probably glutathione conjugates. The amount of styrene glycol was very small. Exposure of rat to cigarette smoke had no effect on the metabolism of styrene oxide or on the amount of covalent binding to the protein and nucleic acid fractions of the perfused lungs.

The effects of cigarette smoke on the metabolism of exogenous PGE2 and PGF2 alpha were investigated in isolated rat and hamster lungs. When isolated lungs from animals were ventilated with cigarette smoke during pulmonary infusion of 100 nmol of PGE2 or PGF2 alpha, the amounts of the 15-keto-metabolites in the perfusion effluent were decreased. Pre-exposure of animals to cigarette smoke daily for 3 weeks did not change the metabolism of PGE2 when the lungs were ventilated with air. Cigarette smoke ventilation of lungs from pre-exposed animals caused, however, a similar decrease in the metabolism of PGE2 as in animals not previously exposed to smoke. After pulmonary injection of 10 nmol of 14C-PGE2 the radioactivity appeared more rapidly in the effluent during cigarette smoke ventilation suggesting inhibition of the PGE2 uptake mechanism. In rat lungs pulmonary vascular pressor responses to PGE2 and PGF2 alpha were inhibited by smoke ventilation.

Following the injection of 4 nmol of 14C-arachidonic acid into the pulmonary circulation of rat isolated lungs more than 90% of the radioactivity was retained by the lung tissue. When dipyridamole (20 microM) was infused into the pulmonary circulation during 14C-arachidonate injection the amount of radiolabel was increased in diacylglycerols as well as in phosphatidylinositol and phosphatidylserine of the perfused lungs whereas the amount of radioactivity was decreased in phosphatidylethanolamine. When dipyridamole was infused into the lungs prelabelled with 14C-arachidonic acid the distribution of radiolabel in different lung lipid fractions was not changed significantly. However, dipyridamole seemed to stimulate the formation of prostacyclin in rat lungs as the amount of 6-keto-PGF1 alpha was increased in the perfusion effluent. The present study indicates that dipyridamole interferes with the incorporation of arachidonic acid into different lipids in rat lungs. In addition, the release of prostacyclin seems to be stimulated by dipyridamole.

14C-labelled arachidonic acid and prostaglandin E2 (PGE2) were infused into the pulmonary circulation of isolated rat and hamster lungs, and the radioactive metabolites were analysed from the nonrecirculating perfusion effluent by thin-layer chromatography. Pulmonary infusion of nicotine (1 or 10 microM for 5 min) did not interfere with the metabolite pattern of arachidonic acid or the metabolism of PGE2 by 15-hydroxyprostaglandin dehydrogenase. Nicotine seems not to be responsible for the previously reported cigarette smoke-induced alterations in the pulmonary metabolism of exogenous arachidonic acid and PGE2.

The fate of [4-14C]-cortisol and [16,16 alpha-3H]-beclomethasone dipropionate following intratracheal application of the substrates into isolated perfused rat lungs was studied. Both substrates were transferred to the perfusion medium, cortisol at a much higher rate than beclomethasone dipropionate. The proportion of different metabolites of the total radioactivity was larger with beclomethasone dipropionate in both the perfusion medium and the lung tissue. The lungs are considered to have a catabolic role in cortisol metabolism.

1. The effects of exposure of rats to cigarette smoke have been studied on the metabolism of vasoactive hormones in isolated lungs from these animals. 2. Rats were exposed for 1 h per day to cigarette smoke for 1 day or for 10 days. 3. Angiotensin I conversion was increased after 1 day's exposure but after 10 days' exposure conversion returned to normal. 4. Inactivation of prostaglandin E2 was decreased after 1 day's exposure. After 10 days' exposure there was a further decrease which could not be attributed to smoke alone. 5. The inactivation of 5-hydroxytryptamine and bradykinin remained unchanged after both short and longer exposures to smoke. 6. The metabolic activity of the lung towards some vasoactive hormones in the pulmonary circulation is affected by exposure of the animal to cigarette smoke and such changes may be relevant to the initiation of cardiovascular changes consequent upon cigarette smoking.

Purified serum samples from asthmatic and psoriatic patients and healthy controls were analysed by high-pressure liquid chromatography (HPLC) and the amounts of leukotrienes were measured from the corresponding HPLC fractions by specific radioimmunoassays. In the serum of healthy controls the amounts of leukotrienes B4, C4 and D4 were very small or negligible. Rather great amount of leukotriene B4 was, however, detected in the serum of many asthmatic and psoriatic patients. The amount of leukotriene B4 was in the serum of asthmatic patients 120 +/- 20 pmol/ml (n = 11, mean +/- SEM) and in that of psoriatic patients 100 +/- 10 pmol/ml (n = 10). The amounts of leukotrienes C4 and D4 were rather small in the serum of most patients. The amount of leukotriene C4 was, however, very high (250 pmol/ml) in the serum of a psoriatic patient. Significant amount of leukotriene D4 was also detected in the serum of this patient. The present study indicated that leukotrienes are formed during blood clotting in the leukocytes of asthmatic and psoriatic patients and that the rate of formation is so high that leukotrienes may have a role in these diseases.

Perfusion effluent from isolated rat and hamster lungs caused a relaxation of superfused strip of bovine coronary artery (BCA). This relaxation was abolished by pulmonary infusion of indomethacin. Pre-exposure of rats and hamsters to cigarette smoke during half an hour before the lung perfusion did not change the degree of this initial relaxation of BCA. Injection of 10 micrograms of sodium arachidonate (AA) into the pulmonary circulation of isolated hamster lungs caused a contraction of BCA, which was not changed by cigarette smoke pre-exposure. When AA (10 micrograms) was injected into the pulmonary circulation of isolated hamster lungs during cigarette smoke ventilation the contractions of superfused BCA and rat stomach strip (RSS) were not significantly different from those during the preceding and following air ventilation. In experiments with isolated rat lungs the initial relaxation of superfused BCA was accompanied by a contraction of superfused RSS. AA injection (10 micrograms) into rat lungs caused a further relaxation of BCA and contraction of RSS, which were abolished by pulmonary infusion of indomethacin. Cigarette smoke ventilation of isolated rat lungs caused a relaxation of superfused BCA, which was not abolished by indomethacin. During cigarette smoke ventilation injection of AA (10 micrograms) into the pulmonary circulation of rat lungs caused a relaxation of BCA and a contraction of RSS. The present study indicates that neither cigarette smoke ventilation nor pre-exposure to cigarette smoke has a drastic effect on the metabolism of arachidonic acid to myotropic compounds in isolated hamster and rat lungs.