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Detopoulou P, Nomikos T, Fragopoulou E, Chrysohoou C, Antonopoulou S. Platelet activating factor in heart failure: potential role in disease progression and novel target for therapy. Curr Heart Fail Rep 2013; 10:122-9. [PMID: 23389700 DOI: 10.1007/s11897-013-0131-2] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
Heart failure (HF) is a complex syndrome with cardiac, renal, neurohormonal and sympathetic nervous system's manifestations, the pathogenesis of which among others is connected to inflammation. PAF has local and systemic effects pertaining to HF progression since it causes a negative inotropic effect, it induces arrhythmias, it induces apoptosis and it is involved in inflammation and atherosclerosis. In the present review the role of PAF in HF will be thoroughly presented along with the relevant data on PAF enzymes and the potential role of PAF metabolic circuit as a novel pharmacological target.
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Affiliation(s)
- Paraskevi Detopoulou
- Department of Nutrition, General Hospital Korgialenio-Benakio, Athanasaki 1, Athens, Greece.
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Kalra BS, Roy V. Efficacy of Metabolic Modulators in Ischemic Heart Disease: An Overview. J Clin Pharmacol 2013; 52:292-305. [DOI: 10.1177/0091270010396042] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
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Ajiro Y, Saegusa N, Giles WR, Stafforini DM, Spitzer KW. Platelet-activating factor stimulates sodium-hydrogen exchange in ventricular myocytes. Am J Physiol Heart Circ Physiol 2011; 301:H2395-401. [PMID: 21949111 DOI: 10.1152/ajpheart.00607.2011] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
Sodium-hydrogen exchanger (NHE), the principal sarcolemmal acid extruder in ventricular myocytes, is stimulated by a variety of autocrine/paracrine factors and contributes to myocardial injury and arrhythmias during ischemia-reperfusion. Platelet-activating factor (PAF; 1-o-alkyl-2-acetyl-sn-glycero-3-phosphocholine) is a potent proinflammatory phospholipid that is released in the heart in response to oxidative stress and promotes myocardial ischemia-reperfusion injury. PAF stimulates NHE in neutrophils and platelets, but its effect on cardiac NHE (NHE1) is unresolved. We utilized quiescent guinea pig ventricular myocytes bathed in bicarbonate-free solutions and epifluorescence to measure intracellular pH (pH(i)). Methylcarbamyl-PAF (C-PAF; 200 nM), a metabolically stable analog of PAF, significantly increased steady-state pH(i). The alkalosis was completely blocked by the NHE inhibitor, cariporide, and by sodium-free bathing solutions, indicating it was mediated by NHE activation. C-PAF also significantly increased the rate of acid extrusion induced by intracellular acidosis. The ability of C-PAF to increase steady-state pH(i) was completely blocked by the PAF receptor inhibitor WEB 2086 (10 μM), indicating the PAF receptor is required. A MEK inhibitor (PD98059; 25 μM) also completely blocked the rise in pH(i) induced by C-PAF, suggesting participation of the MAP kinase signaling cascade downstream of the PAF receptor. Inhibition of PKC with GF109203X (1 μM) and chelerythrine (2 μM) did not significantly affect the alkalosis induced by C-PAF. In summary, these results provide evidence that PAF stimulates cardiac NHE1, the effect occurs via the PAF receptor, and signal relay requires participation of the MAP kinase cascade.
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Affiliation(s)
- Yoichi Ajiro
- Nora Eccles Harrison Cardiovascular Research and Training Institute, Salt Lake City, Utah, USA
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Penna C, Bassino E, Alloatti G. Platelet activating factor: the good and the bad in the ischemic/reperfused heart. Exp Biol Med (Maywood) 2011; 236:390-401. [PMID: 21378031 DOI: 10.1258/ebm.2011.010316] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
The present review is focused on the dual role played by platelet-activating factor (PAF) in ischemia and reperfusion (I/R) injury of the heart. Although the involvement of PAF in the pathogenesis of myocardial reperfusion injury is well established, in the last few years it has emerged that very low concentrations of PAF exert cardioprotective effects, comparable to that afforded by ischemic preconditioning (IP). PAF is a potent phosphoglyceride involved in different pathophysiological conditions affecting the cardiovascular system, including the development of myocardial I/R injury. PAF is released from the I/R myocardium in concentrations (1-10 nmol/L) high enough to negatively modulate coronary circulation as well as electrical and contractile activities. PAF may act either directly, via generation of secondary mediators, or through the activation of inflammatory cells like platelets and polymorphonuclear neutrophils, which exacerbate postischemic myocardial injury. The effects of PAF are mediated through specific receptors (PAFRs) that belong to the superfamily of G protein-coupled receptors. Since cardiomyocytes not only produce PAF but also possess PAFRs, it is likely that PAF acts as an autocrine/paracrine mediator. Although the negative effects exerted by high concentrations of PAF are well established, several recent findings from our and other laboratories have demonstrated that very low concentrations (pmol/L) of PAF infused before ischemia induce cardioprotective effects similar to those afforded by IP, and that endogenous PAF production participates in the induction of IP itself. The IP-like action exerted by low concentrations of PAF is due to the activation/phosphorylation of kinases included in the reperfusion injury salvage kinase (RISK) pathway, such as protein kinase C, Akt/PkB and nitric oxide synthase. Together with the activation of mitochondrial K(ATP) channels, these events may allow prevention of mitochondrial permeability transition pores opening at reperfusion. Moreover, the nitric oxide-dependent S-nitrosylation of L-type Ca(2+) channels induced by PAF reduces intracellular Ca(2+) overload.
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Affiliation(s)
- Claudia Penna
- Dipartimento di Scienze Cliniche e Biologiche, ASO San Luigi, 10043 Orbassano (TO), Italy
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Penna C, Alloatti G, Cappello S, Gattullo D, Berta G, Mognetti B, Losano G, Pagliaro P. Platelet-activating factor induces cardioprotection in isolated rat heart akin to ischemic preconditioning: role of phosphoinositide 3-kinase and protein kinase C activation. Am J Physiol Heart Circ Physiol 2005; 288:H2512-20. [PMID: 15637120 DOI: 10.1152/ajpheart.00599.2004] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Ischemic preconditioning (IP) is a cardioprotective mechanism against myocellular death and cardiac dysfunction resulting from reperfusion of the ischemic heart. At present, the precise list of mediators involved in IP and the pathways of their mechanisms of action are not completely known. The aim of the present study was to investigate the role of platelet-activating factor (PAF), a phospholipid mediator that is known to be released by the ischemic-reperfused heart, as a possible endogenous agent involved in IP. Experiments were performed on Langendorff-perfused rat hearts undergoing 30 min of ischemia followed by 2 h of reperfusion. Treatment with a low concentration of PAF (2 × 10−11 M) before ischemia reduced the extension of infarct size and improved the recovery of left ventricular developed pressure during reperfusion. The cardioprotective effect of PAF was comparable to that observed in hearts in which IP was induced by three brief (3 min) periods of ischemia separated by 5-min reperfusion intervals. The PAF receptor antagonist WEB-2170 (1 × 10−9 M) abrogated the cardioprotective effect induced by both PAF and IP. The protein kinase C (PKC) inhibitor chelerythrine (5 × 10−6 M) or the phosphoinositide 3-kinase (PI3K) inhibitor LY-294002 (5 × 10−5 M) also reduced the cardioprotective effect of PAF. Western blot analysis revealed that following IP treatment or PAF infusion, the phosphorylation of PKC-ε and Akt (the downstream target of PI3K) was higher than that in control hearts. The present data indicate that exogenous applications of low quantities of PAF induce a cardioprotective effect through PI3K and PKC activation, similar to that afforded by IP. Moreover, the study suggests that endogenous release of PAF, induced by brief periods of ischemia and reperfusion, may participate to the triggering of the IP of the heart.
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Affiliation(s)
- Claudia Penna
- Dipartimento di Scienze Cliniche e Biologiche, ASO S. Luigi, Orbassano, Italy
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Tuttle HA, Davis-Gorman G, Goldman S, Copeland JG, McDonagh PF. Platelet-neutrophil conjugate formation is increased in diabetic women with cardiovascular disease. Cardiovasc Diabetol 2003; 2:12. [PMID: 14609437 PMCID: PMC270088 DOI: 10.1186/1475-2840-2-12] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/14/2003] [Accepted: 10/04/2003] [Indexed: 12/28/2022] Open
Abstract
Background More than seventeen million Americans are afflicted with diabetes and these people have four times the rate of coronary heart disease (CHD) as non-diabetics. Furthermore, diabetic women have a 3.8 fold greater risk for CHD compared to diabetic men. Little is known why diabetic women are at an increased risk for CHD. It is possible that diabetic women with cardiovascular disease (CVD) have a greater inflammatory response resulting in an increased platelet neutrophil conjugate formation than diabetic men with CVD or non-diabetic women with CVD. This study tested the hypothesis that platelet-neutrophil conjugates, which are associated with several cardiovascular diseases, are increased in diabetic women with CVD compared to diabetic men with CVD and non-diabetic women with CVD. Methods Platelet-neutrophil conjugates were quantified by flow cytometry. The primary method is through direct binding of the neutrophil PSGL-1 receptor with P-selectin expressed on the platelet. Results In this study, we found when the blood was stimulated with PAF (platelet activating factor), diabetic women without CVD demonstrated an increase in platelet-neutrophil conjugates compared to diabetic women with CVD and non-diabetic women with CVD (% conjugates: 63.3 ± 5.2 vs 46.8 ± 4.3 vs 48.6 ± 3.4, p < 0.05). The stimulation ratio was significantly increased in diabetic and non-diabetic women with CVD in comparison to diabetic men with CVD (ratio: 3.3 ± 0.4 vs 3.3 ± 0.3 vs 2.1 ± 0.3, p < 0.05). Conclusion These results suggest that platelets and neutrophils in diabetic women have a greater potential for activation compared to diabetic men and may contribute to thrombosis/inflammation and the greater severity of coronary heart disease observed in diabetic women as compared to diabetic men.
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Affiliation(s)
- Hillary A Tuttle
- Cardiovascular and Thoracic Surgery and The Sarver Heart Center, University of Arizona Health Sciences Center, Tucson, AZ 85724, USA
| | - Grace Davis-Gorman
- Cardiovascular and Thoracic Surgery and The Sarver Heart Center, University of Arizona Health Sciences Center, Tucson, AZ 85724, USA
| | - Steven Goldman
- Department of Cardiology, Southern Arizona VA Health Care System, Tucson, AZ 85723, USA
| | - Jack G Copeland
- Cardiovascular and Thoracic Surgery and The Sarver Heart Center, University of Arizona Health Sciences Center, Tucson, AZ 85724, USA
| | - Paul F McDonagh
- Cardiovascular and Thoracic Surgery and The Sarver Heart Center, University of Arizona Health Sciences Center, Tucson, AZ 85724, USA
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Montrucchio G, Alloatti G, Camussi G. Role of platelet-activating factor in cardiovascular pathophysiology. Physiol Rev 2000; 80:1669-99. [PMID: 11015622 DOI: 10.1152/physrev.2000.80.4.1669] [Citation(s) in RCA: 261] [Impact Index Per Article: 10.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
Abstract
Platelet-activating factor (PAF) is a phospholipid mediator that belongs to a family of biologically active, structurally related alkyl phosphoglycerides. PAF acts via a specific receptor that is coupled with a G protein, which activates a phosphatidylinositol-specific phospholipase C. In this review we focus on the aspects that are more relevant for the cell biology of the cardiovascular system. The in vitro studies provided evidence for a role of PAF both as intercellular and intracellular messenger involved in cell-to-cell communication. In the cardiovascular system, PAF may have a role in embryogenesis because it stimulates endothelial cell migration and angiogenesis and may affect cardiac function because it exhibits mechanical and electrophysiological actions on cardiomyocytes. Moreover, PAF may contribute to modulation of blood pressure mainly by affecting the renal vascular circulation. In pathological conditions, PAF has been involved in the hypotension and cardiac dysfunctions occurring in various cardiovascular stress situations such as cardiac anaphylaxis and hemorrhagic, traumatic, and septic shock syndromes. In addition, experimental studies indicate that PAF has a critical role in the development of myocardial ischemia-reperfusion injury. Indeed, PAF cooperates in the recruitment of leukocytes in inflamed tissue by promoting adhesion to the endothelium and extravascular transmigration of leukocytes. The finding that human heart can produce PAF, expresses PAF receptor, and is sensitive to the negative inotropic action of PAF suggests that this mediator may have a role also in human cardiovascular pathophysiology.
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Affiliation(s)
- G Montrucchio
- Laboratorio di Immunopatologia Renale, Dipartimento di Medicina Interna, Dipartimento di Biologia Animale e dell'Uomo e Istituto Nazionale di Fisica della Materia, Università di Torino, Torino, Italy
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Mueller HW, Haught CA, McNatt JM, Cui K, Gaskell SJ, Johnston DA, Willerson JT. Measurement of platelet-activating factor in a canine model of coronary thrombosis and in endarterectomy samples from patients with advanced coronary artery disease. Circ Res 1995; 77:54-63. [PMID: 7788882 DOI: 10.1161/01.res.77.1.54] [Citation(s) in RCA: 49] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
Platelet-activating factor (PAF, 1-O-alkyl-2-acetyl-sn-glycero-3-phosphocholine) is a potent phospholipid mediator of numerous inflammatory and thrombotic responses. The purpose of this study was to determine if PAF synthesis is elevated in damaged coronary arteries after a sustained period of cyclic flow variation (CFV), a phenomenon caused by alternating periods of thrombosis and reperfusion at sites of endothelial injury. Cyclic flow was established and maintained in the left anterior descending coronary arteries (LADs) of 10 dogs. After 8 hours of CFV, the section of damaged LAD containing the thrombus and control sections of the circumflex artery, carotid artery, and saphenous vein was excised, and the total lipids were extracted. The PAF was then purified by silica column chromatography and high-performance liquid chromatography and assayed by both a rabbit platelet bioassay and a PAF radioimmunoassay. With the platelet bioassay, PAF levels of 8.9 +/- 4.0 (range, 4.8 to 15.5) pg/mg wet wt were found in the damaged LADs from the 10 dogs. This PAF bioactivity was completely inhibited by a PAF receptor antagonist. When the radioimmunoassay was used, slightly higher PAF levels of 16.3 +/- 12.9 (range, 4.5 to 41.8) pg/mg wet wt were observed in the LADs. Overall, these PAF levels were 3- to 64-fold higher than in the control vessels when either assay method was used. Although increases in PAF were observed in the damaged LADs, measurements of PAF in blood samples taken from the LAD and the aorta (control) failed to demonstrate any site-specific increase of PAF in the blood. In related experiments, PAF was also measured in 23 endarterectomy samples taken from the coronary arteries of 16 patients with severe atherosclerosis. The PAF levels in these samples were highly variable (2.9 +/- 2.2 [range, 0.3 to 8.5] pg/mg wet wt) and showed no correlation with tissue mass, suggesting that PAF is affected by factors other than the simple presence of atherosclerotic tissue in the vessel. These findings provide direct evidence that PAF is synthesized locally at the site of endothelial injury during thrombosis and that PAF accumulates in the atherosclerotic plaque of some patients with advanced coronary artery disease.
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Affiliation(s)
- H W Mueller
- Division of Cardiology, University of Texas Health Science Center, Houston 77030, USA
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Ambrosio G, Oriente A, Napoli C, Palumbo G, Chiariello P, Marone G, Condorelli M, Chiariello M, Triggiani M. Oxygen radicals inhibit human plasma acetylhydrolase, the enzyme that catabolizes platelet-activating factor. J Clin Invest 1994; 93:2408-16. [PMID: 8200975 PMCID: PMC294448 DOI: 10.1172/jci117248] [Citation(s) in RCA: 111] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023] Open
Abstract
Platelet-activating factor (PAF) can exert profound inflammatory effects at very low concentrations. In plasma, PAF is hydrolyzed to lyso-PAF by acetylhydrolase, an enzyme that circulates bound to LDL. Previous studies suggest that oxygen radicals may act synergistically with PAF to potentiate tissue injury. However, mechanisms underlying this interaction have not been elucidated. In this study we investigated whether oxygen radicals may inactivate PAF acetylhydrolase. PAF acetylhydrolase activity was measured in human plasma and purified LDL before and after exposure to radicals (10-20 nmol/min per ml) generated by xanthine/xanthine oxidase. Oxygen radicals induced > 50% loss of PAF acetylhydrolase activity within 60 s and almost complete inactivation by 10 min. This phenomenon was irreversible and independent of oxidative modification of LDL. Inactivation occurred without changes in the affinity constant of the enzyme (Km was 17.9 microM under control conditions and 15.1 microM after exposure to oxygen radicals). Inactivation was prevented by the scavengers superoxide dismutase or dimethylthiourea or by the iron chelator deferoxamine. Thus, superoxide-mediated, iron-catalyzed formation of hydroxyl radicals can rapidly and irreversibly inactivate PAF acetylhydrolase. Since concomitant production of PAF and oxygen radicals can occur in various forms of tissue injury, inactivation of acetylhydrolase might represent one mechanism by which oxygen radicals may potentiate and prolong the proinflammatory effects of PAF.
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Affiliation(s)
- G Ambrosio
- Department of Medicine, Federico II School of Medicine, Naples, Italy
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Filep JG, Földes-Filep E. Modulation by nitric oxide of platelet-activating factor-induced albumin extravasation in the conscious rat. Br J Pharmacol 1993; 110:1347-52. [PMID: 8306074 PMCID: PMC2175884 DOI: 10.1111/j.1476-5381.1993.tb13967.x] [Citation(s) in RCA: 42] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023] Open
Abstract
1. The objective of this study was to assess whether or not endogenous nitric oxide (NO) could mediate the hypotensive response to platelet-activating factor (PAF) and modulate PAF-induced microvascular albumin leakage in the conscious rat. 2. PAF (0.19 and 1.9 nmol kg-1, i.v.) evoked dose-dependent hypotension and significantly enhanced albumin extravasation in the large airways, pancreas, stomach and duodenum 15 min after its administration. Inhibition of NO synthesis by NG-nitro-L-arginine methyl ester (L-NAME, 0.125-2 mg kg-1, i.v.) produced marked dose-dependent increases in albumin accumulation (up to 290%) in large airways, liver, spleen, pancreas, kidney, stomach and duodenum as measured by the extravasation of Evans blue dye. L-NAME (2 mg kg-1) treatment markedly potentiated PAF (1.9 nmol kg-1)-induced albumin extravasation in these tissues, whereas it did not modify the hypotensive response to PAF. 3. Maintenance of mean arterial blood pressure at the level observed following 2 mg kg-1 L-NAME by infusion of noradrenaline (620-790 ng kg-1 min-1) neither affected significantly albumin extravasation nor potentiated the permeability effect of PAF in the vascular beds studied with the exception of large airways, where noradrenaline mimicked the effects of L-NAME. 4. These results indicate that inhibition of endogenous NO formation leads to an increase in albumin extravasation and to potentiation of the vascular permeability effect of PAF, whereas the hypotensive action of PAF seems to be independent of NO formation in the conscious rat. These data suggest an important role for NO in the regulation of albumin extravasation.
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Affiliation(s)
- J G Filep
- Maisonneuve-Rosemont Hospital, Department of Medicine, University of Montréal, Québec, Canada
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Filep JG, Földes-Filep E, Sirois P. Nitric oxide modulates vascular permeability in the rat coronary circulation. Br J Pharmacol 1993; 108:323-6. [PMID: 8448583 PMCID: PMC1907960 DOI: 10.1111/j.1476-5381.1993.tb12803.x] [Citation(s) in RCA: 63] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023] Open
Abstract
1. The objective of the present study was to assess whether inhibition of nitric oxide (NO) production could modulate vascular permeability in the coronary circulation in conscious rats. 2. Intravenous injection of NG-nitro-L-arginine methyl ester (L-NAME, 2 mg kg-1) resulted in a slowly developing hypertension and evoked twofold increases in vascular permeability in the left ventricle and right atrium as measured by the extravasation of Evans blue dye. Maintenance of mean arterial blood pressure at the level observed following L-NAME injection by infusion of noradrenaline (620-820 ng kg-1 min-1) did not induce significant protein extravasation in the coronary circulation. 3. L-NAME treatment markedly enhanced (up to 490%) protein extravasation both in the left ventricle and right atrium in response to platelet-activating factor (PAF, 1.9 nmol kg-1, i.v.) and endothelin-1 (1 nmol kg-1, i.v.). Noradrenaline infusion potentiated (up to 69%) endothelin-1-induced protein extravasation. The permeability effect of PAF was only slightly enhanced by noradrenaline. 4. The present findings indicate that inhibition of endogenous NO synthesis leads to an increase in protein extravasation and to potentiation of the permeability effects of PAF and endothelin-1 in the coronary circulation. These results also suggest that NO may be an important regulator of vascular permeability under physiological and pathological conditions.
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Affiliation(s)
- J G Filep
- Department of Pharmacology, Faculty of Medicine, University of Sherbrooke, P.Q., Canada
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Yoshikawa T, Takahashi S, Naito Y, Ueda S, Tanigawa T, Yoshida N, Kondo M. Effects of a platelet-activating factor antagonist, CV-6209, on gastric mucosal lesions induced by ischemia-reperfusion. Lipids 1992; 27:1058-60. [PMID: 1487954 DOI: 10.1007/bf02535589] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Recent research was shown that oxygen-derived free radicals are involved in the pathogenesis of various diseases, including ischemia-reperfusion injury. We have also reported that oxygen-derived free radicals and lipid peroxidation may play an important role in gastric mucosal injury induced by ischemia-reperfusion. The hypoxanthine-xanthine oxidase system and neutrophils are considered important sources of oxygen-derived free radicals in this process. In recent years, it also has been shown that serum platelet-activating factor (PAF) levels increased during ischemia-reperfusion, and that induction of superoxide generation by neutrophils is one of the important biological effects of PAF. In the present study, we examined the effect of CV-6209, a specific PAF receptor antagonist, on gastric mucosal injury induced by ischemia-reperfusion, to shed some light on the possible involvement of PAF in such lesions. CV-6209 significantly attenuated the gastric mucosal injury induced by ischemia-reperfusion, and inhibited both an increase of thiobarbituric acid reactive substances and a decrease of alpha-tocopherol in gastric mucosa after ischemia-reperfusion. However, CV-6209 had no effect on gastric mucosal blood flow during ischemia-reperfusion. These results suggest that endogenous PAF may play an important role in gastric mucosal injury induced by ischemia-reperfusion, and that CV-6209 exerts its beneficial effect mainly by inhibiting neutrophil superoxide production induced by PAF.
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Affiliation(s)
- T Yoshikawa
- First Department of Medicine, Kyoto Prefectural University of Medicine, Japan
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Chakrabarty S, Fluck DS, Flores NA, Sheridan DJ. Effects of the PAF antagonists BN50726 and BN50739 on arrhythmogenesis and extent of necrosis during myocardial ischaemia/reperfusion in rabbits. Br J Pharmacol 1992; 107:705-9. [PMID: 1472967 PMCID: PMC1907739 DOI: 10.1111/j.1476-5381.1992.tb14510.x] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
1. The effects of two novel platelet activating factor (PAF) antagonists BN50726 and BN50739 on arrhythmias, haemodynamics and extent of necrosis during myocardial ischaemia and reperfusion were investigated in anaesthetized rabbits subjected to coronary artery ligation. 2. BN50739 reduced heart rate prior to coronary artery occlusion (P < 0.005) but had no other significant haemodynamic effects at this time. BN50739 and BN50726 did not significantly alter heart rate or blood pressure during 30 min of ischaemia or 30 min of reperfusion, compared to control hearts. 3. BN50739 and BN50726 had no effect on the incidence of arrhythmias during ischaemia. BN50726 significantly reduced the incidence of reperfusion ventricular fibrillation compared to controls (0% v 40%, P < 0.05), and improved survival (80% v 39%, P < 0.05). Similar trends were observed with BN50739. 4. BN50726 reduced the extent of necrosis compared to control hearts (18 +/- 2% v 30 +/- 3%, P < 0.01). A similar trend was observed with BN50739. 5. These results demonstrate that PAF antagonism with BN50726 attenuates reperfusion-induced arrhythmias and preserves myocardium in the early phase of ischaemia, independently of haemodynamic effects.
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Affiliation(s)
- S Chakrabarty
- Academic Cardiology Unit, St Mary's Hospital Medical School, London
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Massey CV, Kohout TA, Gaa ST, Lederer WJ, Rogers TB. Molecular and cellular actions of platelet-activating factor in rat heart cells. J Clin Invest 1991; 88:2106-16. [PMID: 1661298 PMCID: PMC295814 DOI: 10.1172/jci115540] [Citation(s) in RCA: 28] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
Platelet-activating factor (PAF) is a phospholipid with cardiovascular actions at low concentrations (1-100 nM) but with uncertain direct myocardial actions. We investigated the cellular and molecular effects of PAF on heart cells using isolated adult and neonatal rat myocytes. Addition of PAF, in the superfusion solution, decreased twitch amplitude and contractile velocity in both systems. Concentrations of PAF below 1 nM stimulated reproducible responses with maximal effects seen at 100 nM. These functional actions of PAF could be blocked by the known PAF antagonist, BN 50739, in a dose-dependent manner. Parallel biochemical studies showed that nanomolar PAF rapidly stimulated the phosphoinositide pathway in cultured myocytes, evidenced by the accumulation of [3H]inositol phosphates in prelabeled cultured myocytes. The potency and specificity of PAF, as well as the time course, for the response were nearly identical in the biochemical and functional assays. PAF produced no functional changes in protein kinase C-depleted myocytes, but it did stimulate inositol trisphosphate accumulation in such cells. We conclude that: (a) PAF exerts a direct negative inotropic effect on myocardial tissue; (b) the effects of PAF are mediated by a specific, high affinity cardiac receptor; (c) an underlying biochemical mechanism for the action of PAF includes the activation of the phospholipase C/phosphatidylinositol intracellular signaling pathway, which leads to activation of protein kinase C.
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Affiliation(s)
- C V Massey
- Department of Medicine, University of Maryland School of Medicine, Baltimore 21201
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Filep JG, Sirois MG, Rousseau A, Fournier A, Sirois P. Effects of endothelin-1 on vascular permeability in the conscious rat: interactions with platelet-activating factor. Br J Pharmacol 1991; 104:797-804. [PMID: 1667286 PMCID: PMC1908850 DOI: 10.1111/j.1476-5381.1991.tb12509.x] [Citation(s) in RCA: 97] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
1. The objectives of the present experiments were to assess the effects of endothelin-1 on the macrovascular permeability in selected vascular beds, to study the involvement of platelet-activating factor (PAF) in vascular responses to endothelin-1 and to examine the vascular effects of combined administration of endothelin-1 and PAF in conscious rats. 2. Intravenous bolus injection of endothelin-1 (0.1-2 nmol kg-1) resulted in a dose-dependent biphasic change in mean arterial blood pressure (MABP) with initial transient hypotension followed by a prolonged pressor action. These changes were accompanied by a dose-dependent increase in haematocrit values. 3. Endothelin-1 (0.1 and 1 nmol kg-1) increased dose-dependently the vascular permeability of the trachea, upper and lower bronchi, stomach, duodenum, spleen and kidney (up to 240%) as measured by the extravasation of Evans blue dye. The permeability of pulmonary parenchyma, liver and pancreas was not affected significantly by endothelin-1 treatment. 4. Pretreatment of animals with the specific PAF receptor antagonist, WEB 2086 (1 mg kg-1, i.v.) or BN 52021 (10 mg kg-1, i.v.) reduced the endothelin-1 (1 nmol kg-1)-induced rise in haematocrit by about 50 and 30%, respectively. Both antagonists were highly effective at inhibiting protein extravasation in the stomach, duodenum and kidney. On the other hand, BN 52021, but not WEB 2086, significantly attenuated the effect of endothelin-1 on permeability in the lower bronchi and spleen. Neither WEB 2086 nor BN 52021 modified the changes in MABP evoked by endothelin-1.5. When low doses of endothelin-1 (0.1 nmolkg-')and PAF (0.19nmolkg-')were administered simultaneously, enhanced protein extravasation was detected in the upper and lower bronchi, whereas neither endothelin-1 nor PAF by themselves affected vascular permeability in these tissues. These changes occurred in the absence of significant changes in MABP.6. Combined administration of higher doses of endothelin-1 (1nmolkg-') and PAF (1.9nmolkg-') resulted in marked increases (up to 530%) in protein extravasation in the airways, pancreas, stomach and duodenum. The effect of endothelin-1 on permeability was not affected by PAF in the spleen, whereas it was completely inhibited by PAF in the kidney. Combined injection of endothelin-1 and PAF resulted in a slight, but significant increase in MABP.7. The present findings show that endothelin-1 is capable of increasing vascular permeability in selected vascular beds including the airways, gastrointestinal tract and kidney, and suggest that PAF may mediate, in part, its action on permeability, but not its hypotensive action. The present data also suggest that endothelin-1 and PAF can act in concert to increase vascular permeability in rat airways and gastrointestinal tract.
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Affiliation(s)
- J G Filep
- Department of Pharmacology, Faculty of Medicine, University of Sherbrooke, Canada
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Koltai M, Hosford D, Guinot P, Esanu A, Braquet P. PAF. A review of its effects, antagonists and possible future clinical implications (Part II). Drugs 1991; 42:174-204. [PMID: 1717219 DOI: 10.2165/00003495-199142020-00002] [Citation(s) in RCA: 88] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Affiliation(s)
- M Koltai
- Institut Henri Beaufour, Le Plessis Robinson, France
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17
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Flores NA, Sheridan DJ. Electrophysiological and arrhythmogenic effects of platelet activating factor during normal perfusion, myocardial ischaemia and reperfusion in the guinea-pig. Br J Pharmacol 1990; 101:734-8. [PMID: 2076489 PMCID: PMC1917725 DOI: 10.1111/j.1476-5381.1990.tb14149.x] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
1. Platelet activating factor (PAF) is often used to study the effects of platelet activation. While direct myocardial electrophysiological effects of PAF have been described in superfused myocardial tissue, little is known about its actions on the whole heart. 2. The cellular electrophysiological and arrhythmogenic effects of PAF (10(-11)M, 10(-10)M and 10(-9)M) were studied during normal perfusion, global myocardial ischaemia and reperfusion in Langendorff-perfused guinea-pig hearts at 32 degrees C. 3. PAF (10(-9)M) increased the incidence of ventricular fibrillation during ischaemia and reduced action potential duration (APD) during normal perfusion and early myocardial ischaemia (10(-9)M and 10(-10)M). PAF also reduced refractory period (RP) during normal perfusion (10(-9)M) and early ischaemia (10(-9)M and 10(-10)M). PAF prevented recovery of APD (10(-9)M) and RP (10(-9)M and 10(-10)M) during reperfusion. PAF at a concentration of 10(-11)M had no electrophysiological effects. 4. PAF (10(-9)M) increased the QRS width of the electrocardiogram during late ischaemia while 10(-10)M PAF raised pacing threshold during late ischaemia. 5. Perfusion pressure was increased, and developed tension decreased by 10(-9)M PAF. 6. These results demonstrate that PAF has direct myocardial electrophysiological effects in the whole heart which occur during normal perfusion and are capable of augmenting the effects of myocardial ischaemia, but are independent of the presence of platelets.
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Affiliation(s)
- N A Flores
- Academic Cardiology Unit, St. Mary's Hospital Medical School, London
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Williams FM, Collins PD, Tannière-Zeller M, Williams TJ. The relationship between neutrophils and increased microvascular permeability in a model of myocardial ischaemia and reperfusion in the rabbit. Br J Pharmacol 1990; 100:729-34. [PMID: 2207496 PMCID: PMC1917609 DOI: 10.1111/j.1476-5381.1990.tb14083.x] [Citation(s) in RCA: 31] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
1. 111In-labelled neutrophils and 125I-labelled albumin were used to measure neutrophil accumulation and microvascular plasma protein leakage in the ischaemic/reperfused myocardium of anaesthetized rabbits. 2. A period of 30 min coronary artery occlusion followed by 3 h reperfusion resulted in an increase in both 111In and 125I counts in the area at risk (AR) of the myocardium. 3. Pretreatment of 111In-neutrophils in vitro with monoclonal antibody 60.3 directed against the CD18 antigen on neutrophils, followed by intravenous administration, significantly suppressed their accumulation into the AR myocardium. 4. Depletion of circulating neutrophils by use of anti-neutrophil serum or mustine hydrochloride did not affect plasma protein leakage into the AR myocardium. 5. Administration of the platelet activating factor (PAF) antagonist WEB 2086 (10 mg kg-1, i.v.) had no effect on the accumulation of 111In-neutrophils or on plasma protein leakage in the AR myocardium.
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Affiliation(s)
- F M Williams
- Department of Applied Pharmacology, National Heart and Lung Institute, London
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