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Abstract
Neutral models of evolution assume the absence of natural selection. Formerly confined to ecology and evolutionary biology, neutral models are spreading. In recent years they've been applied to explaining the diversity of baby names, scientific citations, cryptocurrencies, pot decorations, literary lexica, tumour variants and much more besides. Here, we survey important neutral models and highlight their similarities. We investigate the most widely used tests of neutrality, show that they are weak and suggest more powerful methods. We conclude by discussing the role of neutral models in the explanation of diversity. We suggest that the ability of neutral models to fit low-information distributions should not be taken as evidence for the absence of selection. Nevertheless, many studies, in increasingly diverse fields, make just such claims. We call this tendency 'neutral syndrome'.
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Endothelium-derived vasoactive agents, AT1 receptors and inflammation. Pharmacol Ther 2011; 131:187-203. [DOI: 10.1016/j.pharmthera.2010.11.001] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2010] [Accepted: 11/03/2010] [Indexed: 12/25/2022]
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Yamanari H, Nakamura K, Kakishita M, Ohe T. Effects of cyclooxygenase inhibition on endothelial function in hypertensive patients treated with angiotensin-converting enzyme inhibitors. Clin Cardiol 2004; 27:523-7. [PMID: 15471166 PMCID: PMC6654208 DOI: 10.1002/clc.4960270911] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
Abstract
BACKGROUND Cyclooxygenase inhibition restores endothelium-dependent vasodilatation in hypertension, but it is unknown whether it restores endothelial function in hypertensive patients treated with angiotensin-converting enzyme (ACE) inhibitors. HYPOTHESIS The purpose of the present study was to evaluate the effects of cyclooxygenase inhibition on endothelial function in hypertensive patients treated with ACE inhibitors. METHODS Endothelium-dependent flow-mediated dilatation (FMD) and endothelium-independent glyceryl trinitrate-induced dilatation were investigated in 10 patients treated with enalapril (ACE group), 11 patients treated with manidipine and metoprolol (non-ACE group), and 12 normotensive control subjects. After administration of 1000 mg of aspirin, FMD was investigated once again. Plasma cyclic guanosine monophosphate (cGMP) and eicosanoids were also measured during reactive hyperemia before and after aspirin administration. RESULTS Flow-mediated dilatation was more impaired in the non-ACE group than in the ACE group (8.3 +/- 3.8%, 5.7 +/- 1.7%, respectively, p<0.04). Glyceryl trinitrate-induced dilatation was similar in the ACE group, the non-ACE group, and in the control subjects. In the ACE group, FMD was reduced after administration of aspirin (5.3 +/- 4.2%, p<0.05). The percent change in FMD after administration of aspirin correlated significantly with percent change in cGMP (r=0.77, p<0.03; y-intercept, -62.1%, p<0.01). After aspirin administration, levels of thromboxane B2 and 6-keto-prostaglandin(1alpha) were significantly decreased compared with those before aspirin administration in all groups. CONCLUSIONS Cyclooxygenase inhibition may reduce the beneficial effect on endothelium-dependent vasodilatation induced by ACE inhibitors. The results suggested that prostacyclin in addition to nitric oxide plays a significant role in the restoration of endothelial function in hypertensive patients treated with ACE inhibitors.
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Affiliation(s)
- Hiroshi Yamanari
- Department of Cardiovascular Medicine, Okayama University Medical School, Okayama, Japan.
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Iyer SN, Yamada K, Diz DI, Ferrario CM, Chappell MC. Evidence that prostaglandins mediate the antihypertensive actions of angiotensin-(1-7) during chronic blockade of the renin-angiotensin system. J Cardiovasc Pharmacol 2000; 36:109-17. [PMID: 10892668 DOI: 10.1097/00005344-200007000-00015] [Citation(s) in RCA: 68] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
Prostaglandins are known to participate in the antihypertensive actions of angiotensin-converting enzyme (ACE) inhibition and angiotensin type 1 (AT1)-receptor antagonism. Because angiotensin-(1-7) [Ang-(1-7)] is markedly elevated after prolonged ACE-inhibitor treatment, we determined whether the antihypertensive effects of Ang-(1-7) were mediated by release of prostaglandins. Male spontaneously hypertensive rats (SHRs, 10 weeks) were treated for 9 days with either lisinopril (20 mg/kg) or losartan (10 mg/kg) or a combination of both drugs. Rats were implanted with catheters in the carotid artery and jugular vein to record blood pressure and to infuse drug solutions, respectively. Neutralization of circulating Ang-(1-7) by monoclonal antibody resulted in a dose-dependent increase in blood pressure in SHRs treated with either lisinopril or losartan. Administration of CGS 24592 to block Ang-(1-7) formation also resulted in an increase in blood pressure that was comparable to antibody infusion. However, Ang-(1-7) blockade evoked a greater elevation in blood pressure in the lisinopril and lisinopril/losartan-treated rats in comparison to those treated with losartan alone. Acute treatment with the cyclooxygenase (COX) inhibitor indomethacin increased blood pressure to a similar extent to that of CGS 24592, as well as blocked the increase in pressure with the neprilysin inhibitor in the lisinopril/losartan group. In the losartan-treated animals, however, indomethacin increased blood pressure by a larger extent than that of the Ang-(1-7) antibody or CGS 24592, and CGS 24592 did not abolish the subsequent pressor response to indomethacin in these animals. In contrast to the antibody or neprilysin inhibitor, administration of the Ang-(1-7) antagonist D-[Ala7]-Ang-(1-7) increased blood pressure to a similar extent in lisinopril or losartan treatments. Moreover, D-[Ala7]-Ang-(1-7) increased blood pressure to a comparable extent as indomethacin and blocked any further increase with the COX inhibitor in the losartan-treated SHRs. High-resolution emulsion autoradiography revealed 125I-[Sarcosine1, Threonine8]-Ang II (Sarthran) binding in the mesenteric artery and thoracic aorta in the presence of both LOS and the AT2 antagonist PD123319. The non-AT1/non-AT2 Sarthran binding was displaced by Ang-(1-7), DALA, or Ang II. These studies suggest that vasodilatory eicosanoids mediate the antihypertensive effects of endogenous Ang-(1-7) in both LIS and LIS/LOS therapies. Furthermore, in the presence of AT1-receptor blockade, Ang II may interact with a DALA-sensitive site to promote eicosanoid release.
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Affiliation(s)
- S N Iyer
- Hypertension and Vascular Disease Center, Wake Forest University School of Medicine, Winston-Salem, North Carolina 27157-1032, USA
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Yamamoto M, Fukui M, Shou I, Wang LN, Sekizuka K, Suzuki S, Shirato I, Tomino Y. Effects of treatment with angiotensin-converting enzyme inhibitor (ACEI) or angiotensin II receptor antagonist (AIIRA) on renal function and glomerular injury in subtotal nephrectomized rats. J Clin Lab Anal 1998; 11:53-62. [PMID: 9021525 PMCID: PMC6760726 DOI: 10.1002/(sici)1098-2825(1997)11:1<53::aid-jcla9>3.0.co;2-l] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
The aim of this study was to determine if treatment with angiotensin-converting enzyme inhibitors (ACEI) or angiotensin II receptor antagonists (AIIRA) might decrease urinary albumin excretion and prevent glomerular enlargement and glomerulosclerosis in subtotal (5/6) nephrectomized rats. Morphometric image analysis of glomeruli was also performed in the subtotal nephrectomized rats. The nephrectomized rats were treated with ACEI (enalapril 100 mg/l), AIIRA (L-158,809 10 mg/l) or TRX (reserpine 5 mg/ l, hydralazine 80 mg/l, and hydrochlorothiazide 25 mg/l) and euthanized at 16 weeks after renal ablation. Treatments were started at 2 weeks (early treatment: Group I) or 8 weeks (later treatment: Group II) after the ablation. ACEI and AIIRA treatments were equally and significantly effective in limiting albuminuria and progression of glomerular sclerosis. TRX was also as effective in decreasing urinary albumin excretion and preserving the renal function as ACEI or AIIRA in Group I. The improvement of albuminuria, glomerular enlargement and sclerosis after these treatments in Group II was significantly less than that in Group I. It appears that the early treatment with angiotensin converting enzyme inhibitor, angiotensin II receptor antagonist or reserpine, hydralazine and hydrochlorothiazide (TRX) may prevent glomerular injury in human patients with renal hypertension.
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Affiliation(s)
- M Yamamoto
- Department of Medicine, Juntendo University School of Medicine, Tokyo, Japan
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Partovian C, Benetos A, Pommiès JP, Mischler W, Safar ME. Effects of a chronic high-salt diet on large artery structure: role of endogenous bradykinin. THE AMERICAN JOURNAL OF PHYSIOLOGY 1998; 274:H1423-8. [PMID: 9612345 DOI: 10.1152/ajpheart.1998.274.5.h1423] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Bradykinin activity could explain the blood pressure increase during NaCl loading in hypertensive animals, but its contribution on vascular structure was not evaluated. We determined cardiac mass and large artery structure after a chronic, 4-mo, high-salt diet in combination with bradykinin B2-receptor blockade by Hoe-140. Four-week-old rats were divided into eight groups according to strain [spontaneously hypertensive rats (SHR) vs. Wistar-Kyoto (WKY) rats], diet (0.4 vs. 7% NaCl), and treatment (Hoe-140 vs. placebo). In WKY rats, a high-salt diet significantly increased intra-arterial blood pressure with minor changes in arterial structure independently of Hoe-140. In SHR, blood pressure remained stable but 1) the high-salt diet was significantly associated with cardiovascular hypertrophy and increased arterial elastin and collagen, and 2) Hoe-140 alone induced carotid hypertrophy. A high-salt diet plus Hoe-140 acted synergistically on carotid hypertrophy and elastin content in SHR, suggesting that the role of endogenous bradykinin on arterial structure was amplified in the presence of a high-salt diet.
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Affiliation(s)
- C Partovian
- Department of Internal Medicine, Broussais Hospital, Paris, France
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Hayashi K, Koyama M, Kido H, Egi Y, Kubo Y, Shinyama H, Iwamoto M, Nakamura N, Kagitani Y. Preventative and therapeutic effects of AE0047 on renal injury in stroke-prone spontaneously hypertensive rats. Clin Exp Pharmacol Physiol 1997; 24:831-40. [PMID: 9363365 DOI: 10.1111/j.1440-1681.1997.tb02699.x] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
1. The present study was designed to investigate the preventative and therapeutic effects of AE0047 on renal injury compared with those of nitrendipine in stroke-prone spontaneously hypertensive rats (SHRSP). 2. In the preventative study, drug administration was started before the appearance of renal injury, such as proteinuria. Treatment for 6 weeks with AE0047 (1 and 3 mg/kg, p.o.) led to a dose-related reduction in systolic blood pressure (SBP). Nitrendipine, at doses of 10 and 30 mg/kg, also lowered SBP to a similar degree to that seen with AE0047 at 1 and 3 mg/kg, respectively. 3. In the vehicle-administered SHRSP group, urinary excretion of protein (Uprotein V) increased progressively from 14 weeks of age for another 6 weeks. AE0047 at both doses maintained Uprotein V within normal levels throughout the experimental period. However, the elevation of Uprotein V was only inhibited in the 30 mg/kg nitrendipine-treated group. Urinary N-acetyl-beta-D-glucosaminide (NAG) activity in the vehicle-treated SHRSP group was elevated. Urinary NAG activity remained at a low level only in AE0047-treated groups. 4. Histopathological examination revealed severe lesions (i.e. fibrinoid necrosis, proliferative vasculitis and glomerular lesions) of the kidney in SHRSP. AE0047 treatment at each dose attenuated the development of renal lesions in SHRSP. In contrast, nitrendipine, at 10 mg/kg, was ineffective against the development of renal lesions. Although nitrendipine at 30 mg/kg suppressed the development of renal lesions, this effect was still weaker than that seen with AE0047 at 1 mg/kg. 5. In the therapeutic study, drugs were administered to 17-week-old SHRSP with moderate renal damage for 10 days. Treatment with AE0047 (1 and 3 mg/kg) produced dose-dependent decreases in Uprotein V. In the nitrendipine-treated group, Uprotein V tended to decrease but the changes were not significant. 6. Histopathological studies revealed that 3 mg/kg AE0047 improved renal lesions, such as fibrinoid necrosis, proliferative vasculitis and glomerular lesions, whereas 30 mg/kg nitrendipine did not. 7. Taken together, the results indicate that AE0047 is capable of preventing proteinuria as well as renal lesions, in part via a mechanism independent of its depressor action on SBP. Furthermore, AE0047 improves proteinuria and renal lesions in proteinuria-established SHRSP. Thus, AE0047 may have therapeutic potential in suppressing either the development or the progression of renal disease in hypertensive patients.
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Affiliation(s)
- K Hayashi
- Pharmacology Laboratories, Green Cross Corporation, Osaka, Japan.
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8
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Benetos A, Levy BI, Lacolley P, Taillard F, Duriez M, Safar ME. Role of angiotensin II and bradykinin on aortic collagen following converting enzyme inhibition in spontaneously hypertensive rats. Arterioscler Thromb Vasc Biol 1997; 17:3196-201. [PMID: 9409311 DOI: 10.1161/01.atv.17.11.3196] [Citation(s) in RCA: 56] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
We previously showed that chronic angiotensin-converting enzyme (ACE) inhibition prevented the increase in aortic collagen in spontaneously hypertensive rats (SHRs) independently of blood pressure reduction. The aim of the present study was to determine whether the effects of ACE inhibition on aortic fibrosis were due to inhibition of angiotensin II formation, preservation of bradykinin, or a combination of both. Four week-old SHRs were treated for 4 months with the ACE inhibitor quinapril, quinapril with the bradykinin B2 receptor antagonist Hoe 140, or the angiotensin II AT1 receptor antagonist CI996. Control SHR and Wistar-Kyoto (WKY) rats received a placebo for the same period of time. At the end of the treatment, as compared to conscious SHR and WKY controls, quinapril completely prevented the development of hypertension, whereas quinapril-Hoe 140 and the AT1 receptor antagonist produced only a partial reduction of blood pressure. In relation with blood pressure changes, aortic hypertrophy was significantly prevented by quinapril but not by quinapril-Hoe 140 or CI996. In contrast, aortic collagen accumulation was completely prevented by all three treatments. The study provides evidence that in young live SHRs, the prevention of aortic collagen accumulation is independent of blood pressure changes and bradykinin preservation and involves exclusively angiotensin II inhibition through AT1 receptors.
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MESH Headings
- Angiotensin II/antagonists & inhibitors
- Angiotensin II/physiology
- Angiotensin Receptor Antagonists
- Angiotensin-Converting Enzyme Inhibitors/administration & dosage
- Angiotensin-Converting Enzyme Inhibitors/pharmacology
- Angiotensin-Converting Enzyme Inhibitors/therapeutic use
- Animals
- Aorta, Thoracic/drug effects
- Aorta, Thoracic/metabolism
- Aorta, Thoracic/pathology
- Bradykinin/administration & dosage
- Bradykinin/analogs & derivatives
- Bradykinin/antagonists & inhibitors
- Bradykinin/pharmacology
- Bradykinin/physiology
- Bradykinin/therapeutic use
- Bradykinin Receptor Antagonists
- Collagen/metabolism
- Drug Therapy, Combination
- Hemodynamics/drug effects
- Hypertension/drug therapy
- Hypertension/genetics
- Hypertension/metabolism
- Hypertension/prevention & control
- Hypertrophy
- Imidazoles/administration & dosage
- Imidazoles/pharmacology
- Imidazoles/therapeutic use
- Isoquinolines/administration & dosage
- Isoquinolines/pharmacology
- Isoquinolines/therapeutic use
- Male
- Quinapril
- Rats
- Rats, Inbred SHR
- Rats, Inbred WKY
- Receptor, Angiotensin, Type 1
- Receptor, Angiotensin, Type 2
- Receptor, Bradykinin B2
- Tetrahydroisoquinolines
- Tetrazoles/administration & dosage
- Tetrazoles/pharmacology
- Tetrazoles/therapeutic use
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Stier CT, Chander PN, Belmonte A, Inamdar RS, Mistry M. Beneficial action of beraprost sodium, a prostacyclin analog, in stroke-prone rats. J Cardiovasc Pharmacol 1997; 30:285-93. [PMID: 9300310 DOI: 10.1097/00005344-199709000-00003] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Beraprost sodium is a stable analog of the vasodilator, platelet antiaggregatory eicosanoid, prostacyclin. Experiments were performed to determine whether long-term therapy with beraprost produces vascular protective effects in saline-drinking stroke-prone spontaneously hypertensive rats (SHRSPs). Oral beraprost at 30, 100, or 300 micrograms/kg/day starting at 8.4 weeks of age did not affect the progressive increase of systolic blood pressure (measured by tail-cuff plethysmography) in these rats. Additional experiments in SHRSPs, prepared for continuous monitoring of blood pressure by radiotelemetry, revealed that oral beraprost administration reduced mean arterial pressure but that these hypotensive responses were not sustained (< 4 h). In all SHRSPs receiving oral beraprost, proteinuria and cerebrovascular lesions developed. In contrast, continuous subcutaneous infusion of beraprost at 2.8 mg/kg/day from age 8.3-12.3 weeks reduced systolic blood pressure and markedly diminished the development of renal lesions and the occurrence of stroke in saline-drinking SHRSPs. Beraprost at 0.9 mg/kg/day reduced blood pressure less than did 2.8 mg/kg/day and provided partial protection against cerebral and renal lesions after a 4-week infusion period. These results indicate that long-term subcutaneous infusion of beraprost can protect saline-drinking SHRSPs against stroke and renal damage. This effect is not readily dissociated from the ability of beraprost to reduce blood pressure in SHRSPs.
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Affiliation(s)
- C T Stier
- Department of Pharmacology, New York Medical College, Valhalla 10595, USA
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10
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Abstract
Advances in molecular medicine and pharmacology have allowed clinicians to critically reassess the renin-angiotensin system. Angiotensin II (AII) participates in the control of cardiovascular function and electrolyte balance, and plays a part in the regulation of cellular oncogenes and the expression of growth factors. The expression of the proteins of the renin-angiotensin system in organs other than the kidneys suggests that these diverse actions are associated with the peptide in the local environment. Tissue renin-angiotensin activity has prompted the investigation of alternate pathways for the production of AII and characterization of novel forms of angiotensin peptides that counteract the vasoconstrictor and proliferative actions of AII. The heptapeptide angiotensin-(1-7) appears to be critically involved in regulating the angiotensinogen activity of AII through stimulation of vasodilator prostaglandins and release of nitric oxide. Study in this area has been accelerated by the identification of receptors that convey the actions of angiotensin peptides at the cellular level and the pharmacologic characterization of agents that inhibit the ability of AII to bind to target receptors. The introduction of a new class of orally active AII-receptor blockers has provided a specific test of the role of AII in the development of essential hypertension and the potential for improved therapy for hypertension and cardiac and vascular sequelae.
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Affiliation(s)
- C M Ferrario
- Hypertension Center, Bowman Gray/Baptist Hospital Medical Center, Wake Forest University, Winston-Salem, NC 27157, USA
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11
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Sharma JN, Uma K, Noor AR, Rahman AR. Blood pressure regulation by the kallikrein-kinin system. GENERAL PHARMACOLOGY 1996; 27:55-63. [PMID: 8742494 DOI: 10.1016/0306-3623(95)00028-3] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
1. The kallikrein-kinin system has a significant role in regulating arterial blood pressure. 2. Reduced formation of the kinin compontents may cause hypertensive diseases. This is because of the fact that this system is responsible for vasodilatation, reduction in total peripheral resistance, natriuresis, diuresis, increasing renal blood flow and releasing various vasodilator agents. 3. Reduced kinin-kallikrein generation in hypertensive subjects may also be associated with genetic and environmental defects. 4. The kallikrein-kinin system when administered to hypertensive patients can lower their raised blood pressure to normotensive levels. 5. The mode of action of angiotensin-converting enzyme inhibitors principally may be dependent on the kinin system protection.
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Affiliation(s)
- J N Sharma
- Department of Pharmacology, Universiti Sains Malaysia, Kelantan
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Liu YH, Yang XP, Sharov VG, Sigmon DH, Sabbath HN, Carretero OA. Paracrine systems in the cardioprotective effect of angiotensin-converting enzyme inhibitors on myocardial ischemia/reperfusion injury in rats. Hypertension 1996; 27:7-13. [PMID: 8591891 DOI: 10.1161/01.hyp.27.1.7] [Citation(s) in RCA: 88] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
After transient episodes of ischemia, benefits of thrombolytic or angioplastic therapy may be limited by reperfusion injury. Angiotensin-converting enzyme inhibitors protect the heart against ischemia/reperfusion injury, an effect mediated by kinins. We examined whether the protective effect of the angiotensin-converting enzyme inhibitor ramiprilat on myocardial ischemia/reperfusion is due to kinin stimulation of prostaglandin and/or nitric oxide release. The left anterior descending coronary artery of Lewis inbred rats was occluded for 30 minutes, followed by 120 minutes of reperfusion. Immediately before reperfusion rats were treated with vehicle, ramiprilat, or the angiotensin II type 1 receptor antagonist losartan. We tested whether pretreatment with the kinin receptor antagonist Hoe 140, the nitric oxide synthase inhibitor NG-nitro-L-arginine methyl ester, or the cyclooxygenase inhibitor indomethacin blocked the effect of ramiprilat on infarct size and reperfusion arrhythmias. In controls, infarct size as a percentage of the area at risk was 79 +/- 3%; ramiprilat reduced this to 49 +/- 4% (P < .001), but losartan had little effect (74 +/- 6%, P = NS). Pretreatment with Hoe 140, NG-nitro-L-arginine methyl ester, or indomethacin abolished the beneficial effect of ramiprilat. Compared with the 30-minute ischemia/120-minute reperfusion group, nonreperfused hearts with 30 minutes of ischemia had significantly smaller infarct size as a percentage of the area at risk, whereas in the 150-minute ischemia group it was significantly larger. This suggests that reperfusion caused a significant part of the myocardial injury, but it also suggests that compared with prolonged ischemia, reperfusion salvaged some of the myocardium. Ventricular arrhythmias mirrored the changes in infarct size. Thus, angiotensin-converting enzyme inhibitors protect the myocardium against ischemia/reperfusion injury and arrhythmias; these beneficial effects are mediated primarily by a kinin-prostaglandin-nitric oxide pathway, not inhibition of angiotensin II formation.
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Affiliation(s)
- Y H Liu
- Department of Medicine, Henry Ford Hospital, Detroit, MI 48202-2689, USA
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Cachofeiro V, Maeso R, Rodrigo E, Navarro J, Ruilope LM, Lahera V. Nitric oxide and prostaglandins in the prolonged effects of losartan and ramipril in hypertension. Hypertension 1995; 26:236-43. [PMID: 7635531 DOI: 10.1161/01.hyp.26.2.236] [Citation(s) in RCA: 46] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
We investigated the role of endogenous nitric oxide, kinins, and prostaglandins in the vasodepressor and renal excretory effects of the angiotensin II receptor antagonist losartan and the angiotensin-converting enzyme inhibitor ramipril administered for 1 week to spontaneously hypertensive rats. To this end, either losartan (10 mg/kg per day) or ramipril (2.5 mg/kg per day) was administered in drinking water with or without simultaneous administration of (1) the nitric oxide synthesis inhibitor Ng-nitro-L-arginine methyl ester (L-NAME, 6 mg/kg per day), (2) the cyclooxygenase inhibitor indomethacin (5 mg/kg per day), (3) the bradykinin B2 receptor antagonist Hoe 140 (0.5 mg/kg per day SC), or (4) L-NAME plus indomethacin. Both losartan and ramipril significantly reduced blood pressure as measured by the tail-cuff method. L-NAME increased blood pressure when administered solely or in combination with losartan. However, L-NAME attenuated the hypotensive effect of ramipril. Indomethacin did not affect blood pressure but it reduced the antihypertensive action of losartan and ramipril. Indomethacin administration did not potentiate the increase in blood pressure induced by L-NAME. However, the concurrent administration of both inhibitors almost totally blunted the vasodepressor action of ramipril. By contrast, losartan administration in the presence of L-NAME and indomethacin increased blood pressure to a level similar to that after losartan plus L-NAME. Hoe 140 did not modify either blood pressure or the hypotensive effects of losartan or ramipril. Increases in diuresis and water intake were observed during ramipril administration. Both effects were blunted only with the concurrent administration of L-NAME and indomethacin.(ABSTRACT TRUNCATED AT 250 WORDS)
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Affiliation(s)
- V Cachofeiro
- Department of Physiology, Complutense University, Medical School, Madrid, Spain
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14
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Abstract
Clinical observations demonstrate an enhanced risk for myocardial infarction in patients with sustained activation of the local and/or systemic renin-angiotensin system, such as a high renin-sodium profile or a heritably enhanced expression of angiotensin converting enzyme. Chronic renin-angiotensin system blockade by angiotensin converting enzyme inhibition in patients with moderate heart failure reduces the rate of myocardial infarction and reinfarction. Preliminary experimental evidence suggests that these clinical observations may be partially explained by a proatherogenic effect of an activated renin-angiotensin system, which can downregulate the endothelial releasability of nitric oxide. Nitric oxide exerts many potentially antiatherogenic effects on endothelium, platelets and low density lipoproteins and indirectly on monocytes and leukocytes. Hypertension-induced chronic distension of elastic arteries upregulates the local renin-angiotensin system in these arteries and thereby downregulates nitric oxide releasability. Enhanced local synthesis of the trophic factor angiotensin-II and reduced releasability of the antitrophic factor nitric oxide appear to cooperate in the trophic adaptation of the distended vessel wall to the enhanced load, but with the disadvantage of enhanced susceptibility for atheroma development due to reduced releasability of nitric oxide. Chronic blockade of the renin angiotensin system by angiotensin converting enzyme inhibitors or by angiotensin receptor type-1 antagonists normalizes a reduced endothelial releasability of nitric oxide in several models, partially by a bradykinin-dependent mechanism. This endothelial protection proved to attenuate the progression of atherosclerosis in experimental models. The antiatherogenic potential of renin angiotensin system blockade in humans is presently under study.
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Affiliation(s)
- J Holtz
- Institut für Pathophysiologie Martin-Luther-Universität Halle-Wittenberg
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15
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Farhy RD, Carretero OA, Ho KL, Scicli AG. Role of kinins and nitric oxide in the effects of angiotensin converting enzyme inhibitors on neointima formation. Circ Res 1993; 72:1202-10. [PMID: 7684331 DOI: 10.1161/01.res.72.6.1202] [Citation(s) in RCA: 133] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
Marked neointima formation occurs after balloon injury to the intima of rat arteries. Angiotensin II has been implicated as a growth factor in this process, since angiotensin converting enzyme (ACE) inhibitors block neointima formation after injury. However, ACE is an important kininase, and its inhibitors may act in part by a kinin-mediated mechanism. Kinins are also known to stimulate synthesis of endothelium-derived relaxing factor/nitric oxide (EDRF/NO) and prostacyclin, both of which have antigrowth effects. To determine whether the effect of ACE inhibitors on neointima formation is due to blockade of angiotensin II synthesis alone and/or inhibition of kinin inactivation, we followed two approaches. First, we compared the inhibition of neointima formation induced by the AT1-type angiotensin II receptor antagonist losartan with that caused by the ACE inhibitor ramipril. We also studied whether a kinin receptor antagonist, Hoe 140, blocks the effect of two different ACE inhibitors, ramipril and enalapril, on neointima formation. In addition, we studied whether the effect of ramipril is blocked by an NO synthesis inhibitor, N omega-nitro-L-arginine-methyl ester (L-NAME). Although both ramipril and losartan significantly reduced neointima formation, ramipril had a more marked effect (p < 0.05 for ramipril versus losartan). The kinin antagonist Hoe 140 reduced the inhibitory effect of ramipril and enalapril by 73% and 62%, respectively. The remaining effect of the ACE inhibitors was now similar to that of losartan. Inhibition of neointima formation by ramipril was also blocked by the NO synthesis inhibitor L-NAME.(ABSTRACT TRUNCATED AT 250 WORDS)
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Affiliation(s)
- R D Farhy
- Hypertension and Vascular Research Division, Ford Hospital, Detroit, MI 48202
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16
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Abstract
Kinins contribute to the acute inflammatory response and are implicated in the pathophysiology of inflammatory disease. The development of therapeutically viable agents that counteract the effects of kinins is, therefore, potentially very rewarding. Since kinin actions are generally mediated via an interaction with cell-surface receptors, one approach is the development of site-specific receptor antagonists. The emphasis in this review is to outline our current understanding of the properties of bradykinin receptors and the potential therapeutic applications for drugs acting at these sites. As a result of the recent introduction of potent bradykinin receptor antagonists and the cloning of bradykinin receptor genes, considerable advances in kinin research can now be confidently anticipated.
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Affiliation(s)
- J M Hall
- Pharmacology Group, King's College London, U.K
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17
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Sigmon DH, Carretero OA, Beierwaltes WH. Angiotensin dependence of endothelium-mediated renal hemodynamics. Hypertension 1992; 20:643-50. [PMID: 1330922 DOI: 10.1161/01.hyp.20.5.643] [Citation(s) in RCA: 67] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Endothelium-derived relaxing factor has been shown to regulate renal blood flow, and inhibition of its synthesis increases blood pressure and renal vascular resistance and decreases renal blood flow. Using the substrate antagonist NW-nitro-L-arginine methyl ester (L-NAME), we tested whether renal vasoconstriction induced by endothelium-derived relaxing factor synthesis inhibition could be mediated in part by angiotensin II. In 14 control rats, 10 mg/kg body wt L-NAME increased blood pressure from 106 +/- 6 to 126 +/- 6 mm Hg (p < 0.001), increased renal vascular resistance by 74% (from 19.3 +/- 2.6 to 33.6 +/- 2.9 resistance units), and decreased renal blood flow by 34% (from 5.9 +/- 0.5 to 3.9 +/- 0.3 ml.min-1.g kidney wt-1, p < 0.005). When six rats were treated with 10 mg/kg body wt of the angiotensin receptor antagonist DuP 753, L-NAME increased blood pressure from 84 +/- 4 to 106 +/- 4 mm Hg (p < 0.001); however, renal vascular resistance increased by only 27% (from 13 +/- 2 to 17 +/- 3 resistance units, p < 0.01; p < 0.05 different from control value) and renal blood flow was unchanged. Likewise, after pretreatment of six rats with 32 micrograms/100 g body wt of the angiotensin converting enzyme inhibitor enalaprilat, L-NAME increased blood pressure from 88 +/- 5 to 124 +/- 6 mm Hg (p < 0.001) and renal vascular resistance by 54% (from 12 +/- 1 to 18 +/- 3 resistance units, p < 0.01; p < 0.05 different from control value) but renal blood flow was unchanged.(ABSTRACT TRUNCATED AT 250 WORDS)
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Affiliation(s)
- D H Sigmon
- Hypertension and Vascular Research Division, Henry Ford Hospital, Detroit, Mich. 48202-2689
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18
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Herman AG. Differences in structure of angiotensin-converting enzyme inhibitors might predict differences in action. Am J Cardiol 1992; 70:102C-108C. [PMID: 1329464 DOI: 10.1016/0002-9149(92)91366-c] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Angiotensin-converting enzyme (ACE) inhibitors probably work by inhibition of tissue-located ACE, and they differ with regard to their relative ability to inhibit ACE in different organs. This apparent tissue selectivity may stem from either differences in tissue bioavailability or from a different affinity for the enzyme. The affinity of the ACE inhibitor for a particular enzyme is not only determined by the structure of the inhibitor, but also by the structure of the enzyme. ACE enzymes from different tissues may be slightly different, and this may have some bearing on the relative affinities of different ACE inhibitors for ACE from different tissues. The duration of inhibition in a particular tissue reflects not only the affinity of that inhibitor for the tissue enzyme, but also reflects the ease or difficulty with which the active ACE inhibitor is released from that tissue. Whether the beneficial effects of ACE inhibitors on experimentally induced myocardial infarction and reperfusion arrhythmias are due to the presence of a sulfhydryl group or are mainly related to the ACE inhibitor-mediated bradykinin potentiation remains a matter of controversy.
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Affiliation(s)
- A G Herman
- Division of Pharmacology, University of Antwerp (UIA), Wilrijk, Belgium
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19
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Lafayette RA, Mayer G, Park SK, Meyer TW. Angiotensin II receptor blockade limits glomerular injury in rats with reduced renal mass. J Clin Invest 1992; 90:766-71. [PMID: 1522231 PMCID: PMC329928 DOI: 10.1172/jci115949] [Citation(s) in RCA: 259] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
The effects of angiotensin II (AII) blockade were compared with the effects of angiotensin converting enzyme inhibition in rats with reduced nephron number. Rats were subjected to five-sixths renal ablation and divided into four groups with similar values for blood pressure and serum creatinine after 2 wk. Group 1 then served as untreated controls, while group 2 received the AII receptor antagonist MK954 (which has previously been designated DuP753), group 3 received the converting enzyme inhibitor enalapril, and group 4 received a combination of reserpine, hydralazine, and hydrochlorothiazide. Micropuncture and morphologic studies were performed 10 wk later. Converting enzyme inhibition, AII receptor blockade, and the combination regimen were equally effective in reversing systemic hypertension (time-averaged systolic blood pressure: group 1, 185 +/- 5 mmHg; group 2, 125 +/- 2 mmHg; group 3, 127 +/- 2 mmHg; group 4, 117 +/- 4 mmHg). Micropuncture studies showed that glomerular transcapillary pressure was reduced significantly by converting enzyme inhibition and by AII blockade but not by the combination regimen (delta P: group 1, 49 +/- 1 mmHg; group 2, 42 +/- 1 mmHg; group 3, 40 +/- 2 mmHg, group 4, 47 +/- 1 mmHg). Reduction of systemic blood pressure was associated with the development of markedly less proteinuria and segmental glomerular sclerosis in rats receiving enalapril and MK954 but not in rats receiving the combination regimen (prevalence of glomerular sclerotic lesions: group 1, 41 +/- 4%; group 2, 9 +/- 1%; group 3, 9 +/- 1%; group 4, 33 +/- 6%). These results indicate that the effects of converting enzyme inhibition on remnant glomerular function and structure depend on reduction in AII activity and are not attributable simply to normalization of systemic blood pressure.
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Affiliation(s)
- R A Lafayette
- Department of Medicine, Stanford University, California 94305
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20
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Cachofeiro V, Sakakibara T, Nasjletti A. Kinins, nitric oxide, and the hypotensive effect of captopril and ramiprilat in hypertension. Hypertension 1992; 19:138-45. [PMID: 1737647 DOI: 10.1161/01.hyp.19.2.138] [Citation(s) in RCA: 98] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
We investigated the role of kinins in the acute depressor effect of captopril and ramiprilat in spontaneously hypertensive rats. Since the vasodepressor action of kinins may be linked to the generation of prostaglandins and endothelium-derived relaxing factors, we also investigated the role of prostaglandins and nitric oxide in the blood pressure reduction caused by angiotensin converting enzyme inhibitors. To this end, we contrasted the hypotensive effects of captopril (10 mg/kg i.v.), ramiprilat (2 mg/kg i.v.), and the angiotensin II antagonist DuP 753 (30 mg/kg i.v.) in spontaneously hypertensive rats with and without pretreatment with a kinin antagonist (D-Arg-Arg-Pro-Hyp-Gly-Thi-Ser-D-Phe-Thi-Arg-trifluoroacetic acid) (200 micrograms/kg/min i.v.), an inhibitor of nitric oxide synthesis (NG-monomethyl-L-arginine) (15 mg/kg + 10 mg/kg/hr i.v.), or an inhibitor of prostaglandin synthesis (indomethacin) (10 mg/kg i.v.). The kinin antagonist did not affect blood pressure in spontaneously hypertensive rats but did attenuate the hypotensive effect of captopril and ramiprilat; the kinin antagonist did not minimize the depressor action of DuP 753. The nitric oxide synthesis inhibitor increased blood pressure in spontaneously hypertensive rats and attenuated the hypotensive effect of captopril, ramiprilat, and DuP 753, but it did not impede the hypotensive effect of sodium nitroprusside. Pretreatment of hypertensive rats with indomethacin did not modify the acute hypotensive effect of ramiprilat or captopril. These data suggest a contribution of endogenous kinins and nitric oxide to the acute antihypertensive effect of captopril and ramiprilat in spontaneously hypertensive rats and of nitric oxide to the hypotensive effect of DuP 753.
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Affiliation(s)
- V Cachofeiro
- Department of Pharmacology, New York Medical College, Valhalla 10595
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