Abstract-We sought to define the contribution of each of the 2 kinin receptors (bradykinin 1 receptor [B 1 R] and bradykinin 2 receptor [B 2 R]) to the cardioprotection of angiotensin-converting enzyme (ACE) inhibition after acute myocardial infarct. Wild-type mice and gene knockout mice missing either B 1 R or B 2 R were submitted to coronary ligation with or without concurrent ACE inhibition and had evaluation of left ventricular systolic capacity by assessment of fractional shortening (FS). Baseline FS was similar in all of the animals and remained unchanged in sham-operated ones. At 3 weeks after myocardial infarct, in the wild-type group there was a 27% reduction of FS (PϽ0.5) without ACE inhibition and 8% with ACE inhibition; in the B 1 R Ϫ/Ϫ groups the FS was reduced by 24% and was no different (at 28%) with ACE inhibition; in the B 2 R Ϫ/Ϫ groups, however, the FS was decreased by 39% and with ACE inhibition was decreased further by 52%. Analysis of bradykinin receptor gene expression in hearts showed that when one receptor was missing, the other became significantly upregulated; but the B 1 R remained highly overexpressed in the B 2 R Ϫ/Ϫ mice throughout, whereas the overexpressed B 2 R became significantly suppressed in the B 1 R Ϫ/Ϫ mice in a manner quantitatively and directionally similar to that of wild-type mice. We conclude that both bradykinin receptors contribute to the cardioprotective bradykinin-mediated effect of ACE inhibition, not only the B 2 R as believed previously; but, whereas with potentiated bradykinin in the absence of B 1 R, the upregulation of B 2 R is simply insufficient to provide full cardioprotection, in the absence of B 2 R, the upregulated B 1 R actually seems to inflict further tissue damage. T he cardioprotective effect of angiotensin-converting enzyme (ACE) inhibition is now well established, 1 but the multiple mechanisms contributing to this effect are still being investigated, and new aspects and functions of the ACE are being reported. 2 The most important and clinically relevant results of ACE inhibition are diminished formation of angiotensin II and prolonged activity of bradykinin. However, whereas the former has been widely explored in studies ranging from basic research to large outcome clinical trials, the latter remains less well understood.Earlier studies explored the physiopharmacology of bradykinin and defined the bradykinin receptor (BR) 1 (B 1 R) and 2 (B 2 R), which mediate its multiple hemodynamic and metabolic effects 3 mainly via use of peptide analogs with agonistic and antagonistic properties. It has generally been accepted that all of the physiologically significant beneficial hemodynamic and metabolic actions of bradykinin are exerted via activation of the constitutive B 2 R. Indeed, acute or chronic infusion of B 2 R antagonists in animals 4 -6 or humans 7 was shown to partly reverse the antihypertensive effect of ACE inhibitors, to prevent the cardioprotective action of ACE inhibition in animals submitted to cardiac ischemia/reperfusion injury, 8,9...

Human essential hypertension (HTN), a polygenic, multifactorial, and highly heterogeneous disorder of unknown etiology, has been shown to have excess maternal transmission in several studies, suggesting a possible mitochondrial involvement. In an effort to assess the contribution of the mitochondrial genome to HTN we initiated a systematic, extended screening of hypertensive individuals to identify potentially pathogenic mtDNA mutations. We applied our newly developed novel class of tests for the detection of mitochondrial mutation involvement in complex diseases to the hypertension data set from 350 pedigrees of white ethnicity and 98 of African American ethnicity ascertained at HTN clinics associated with Boston Medical Center, and we identified families with a likely mitochondrial involvement. We analyzed the sequence of the entire mitochondrial genome in probands from 20 such pedigrees, consisting of 10 African American and 10 white families. Comparison with the reference "Cambridge" sequence revealed a total of 297 base changes, including 24 in the ribosomal RNA (rRNA) genes, 15 in the transfer RNA (tRNA) genes, and 46 amino acid substitutions, with the remainder involving the noncoding regions or synonymous changes. Among the coding region mutations, 30 are novel, with 13 hypertensive probands carrying at least one novel variant, usually in combination with the previously described common polymorphisms, several of which are associated with cardiovascular and renal pathologies. These data will serve as a starting point for large-scale case-control association studies.

Kintsurashvili, Ekaterina, Arvi Duka, Ivana Ignjacev, Gregory Pattakos, Irene Gavras, and Haralambos Gavras. Age-related changes of bradykinin B1 and B2 receptors in rat heart. Am J Physiol Heart Circ Physiol 289: H202-H205, 2005. First published February 11, 2005 doi:10.1152/ajpheart.01287.2004.-Aging is a major risk factor for the development of vascular diseases, such as hypertension and atherosclerosis, that leads to end organ damage and especially heart failure. Bradykinin has been demonstrated to have a cardioprotective role by affecting metabolic processes and tissue perfusion under conditions of myocardial ischemia. Its actions are exerted via the bradykinin B1-and B2-type receptors (B1Rs and B2Rs), but the functional status of these receptors during the aging process is poorly understood. This study aims to investigate whether changes in B1R and B 2R gene and protein expression in rat heart are associated with the age-related alterations of cardiac structure and function. Using real-time PCR, we found that B 1R mRNA expression increased 2.9-fold in hearts of older rats (24 mo of age) compared with younger rats (3 mo of age), whereas B 2R gene expression remained unchanged. Western blot analysis showed that expression of B2R at the protein level is approximately twofold higher in young rats compared with old rats, whereas the B 1R protein is approximately twofold higher in old rats compared with young rats. The present results provide clear functional and molecular evidence that indicate agerelated changes of bradykinin B 1Rs and B2Rs in heart. Because the cardioprotective actions of bradykinin are physiologically mediated via the B 2Rs, whereas the B1Rs become induced by tissue damage, these results suggest that age-related decreases in B2R protein levels may leave the heart vulnerable to ischemic damage, and increases in B 1R expression and activity may represent a compensatory reaction in aging hearts.

With inhibition or absence of the bradykinin B 2 receptor (B2R), B1R is upregulated and assumes some of the hemodynamic properties of B 2R, indicating that both participate in the maintenance of normal vasoregulation or to development of hypertension. Herein we further evaluate the role of bradykinin in normal blood pressure (BP) regulation and its relationship with other vasoactive factors by selectively blocking its receptors. Six groups of Wistar rats were treated for 3 wk: one control group with vehicle alone, one with concurrent administration of B 1R antagonist R-954 (70 g ⅐ kg Ϫ1 ⅐ day Ϫ1 ) and B2R antagonist HOE-140 (500 g ⅐ kg Ϫ1 ⅐ day Ϫ1 ), one with R-954 alone, one with HOE 140 alone, one with concurrent administration of both R-954 and HOE-140 plus the angiotensin antagonist losartan (5 mg ⅐ kg Ϫ1 ⅐ day Ϫ1 ), and one with only losartan. BP was measured continuously by radiotelemetry. Only combined administration of B 1R and B2R antagonists produced a significant BP increase from a baseline of 107-119 mmHg at end point, which could be partly prevented by losartan and was not associated with change in catecholamines, suggesting no involvement of the sympathoadrenal system. The impact of blockade of bradykinin on other vasoregulating systems was assessed by evaluating gene expression of different vasoactive factors. There was upregulation of the eNOS, AT1 receptor, PGE2 receptor, and tissue kallikrein genes in cardiac and renal tissues, more pronounced when both bradykinin receptors were blocked; significant downregulation of AT 2 receptor gene in renal tissues only; and no consistent changes in B 1R and B2R genes in either tissue. The results indicate that both B 1R and B2R contribute to the maintenance of normal BP, but one can compensate for inhibition of the other, and the chronic inhibition of both leads to significant upregulation in the genes of related vasoactive systems. bradykinin inhibition; angiotensin II; vasoactive factors; gene expression DESPITE A LARGE BODY OF LITERATURE on kinins, the role of bradykinin in normal blood pressure (BP) regulation and the specific functions mediated by its B 1 and B 2 type receptors are still insufficiently understood.It has long been accepted that under normal conditions the cardiovascular and renal effects of bradykinin are exerted via the B 2 receptors, which are constitutively abundant in cardiac, renal, and vascular tissues and act by activating the vasoactive components of the prostaglandin-NO cascade (34), whereas the B 1 receptors are inducible by stimuli such as tissue damage, bacterial lipopolysaccharides, etc., and are mostly involved in inflammatory and nociceptive reactions (35,28).Pharmacological experiments using selective antagonists of the B 2 receptor in normotensive rats have given contradictory results: whereas some demonstrated an acute or chronic increase in BP (7, 24), others failed to show change in normal BP (3, 23), although they did show exacerbation of salt-induced (25) or angiotensin-induced hypertension (26) during B 2 recepto...

The angiotensin-converting enzyme (ACE) is a membrane-bound peptidyl dipeptidase known to act on a variety of peptide substrates in the extracellular space. Its most notable functions are the formation of angiotensin II and the degradation of bradykinin. In the current experiments, we found that exogenous ACE added to vascular smooth muscle cell culture strongly induces and upregulates the genes of bradykinin receptors B 1 and B2. This transcriptional regulatory property of ACE was shown to be unrelated to its known enzymatic properties. Indeed, ACE at 3.75 g/ml added in the culture medium of vascular smooth muscle cells was found to cause marked upregulation of the mRNA expression of the genes for the B 1 and B2 receptors of bradykinin by 22-and 11-fold, respectively. This phenomenon was not altered by the addition of specific angiotensin II antagonists for the AT 1 or AT2 receptors. Moreover, the ACE inhibitor captopril, which inhibited ACE enzymatic activity, did not block its effect at the bradykinin receptor gene transcription level. Expression of both receptor genes was completely abolished by actinomycin D. Furthermore, transcriptional upregulation was inhibited by curcumin, suggesting involvement of different transcriptional factors in this phenomenon. Electrophoretic mobility shift assay revealed increase in NF-B and activator protein-1 protein binding for consensus sequences, between ACEtreated cells versus untreated cells. The data indicate a novel biological function of the ACE unrelated to its well-known enzymatic function as a peptidyl dipeptidase. vascular smooth muscle cells; peptidyl dipeptidase; nuclear factor-B; activator protein-1 ANGIOTENSIN-CONVERTING ENZYME (ACE) inhibition is one of the most important advances in cardiovascular pharmacology in the last 35 years. After the first small clinical studies suggested the therapeutic potential of ACE inhibitors for the treatment of hypertension (9, 10) and heart failure (11), this class of drugs became the object of numerous large outcome trials that demonstrated their cardioprotective and nephroprotective properties and are now the most widely prescribed agents for these conditions. Yet, whereas the clinical benefits of ACE inhibition are well established, the multiple functions of ACE and the mechanisms by which its inhibitors exert these benefits are still being investigated.The ACE is a membrane-bound enzyme that acts on a variety of peptide substrates. Skidgel and Erdos (32) have clarified that the peptidyl dipeptidase, which cleaves off HisLeu from angiotensin I to form angiotensin II, is identical to kininase II, which cleaves off Phe-Arg from bradykinin to form inactive residue. Therefore, its inhibition will block the generation of angiotensin II and potentiate the actions of bradykinin. A large body of literature is devoted to dissection of angiotensin-mediated and bradykinin-mediated effects of ACE inhibition, as well as to other aspects of ACE-related functions.In a previous series of experiments studying the interactions of these two...

Abstract-Bradykinin normally exerts its vasodilatory effect via the B 2 receptor (B 2 R), but in this receptor's absence, the B 1 receptor becomes expressed and activated. To explore the mechanism of B 1 R-mediated vasodilation, 8 groups of B 2 R gene-knockout mice received a 2-week infusion of a B 1 R antagonist (300 g · kg Ϫ1 · d Ϫ1 ) or vehicle (groups 1 and 2), B 1 R antagonist or vehicle plus NO inhibition with N-nitro-L-arginine methyl ester (groups 3 and 4), B 1 R antagonist or vehicle plus cyclooxygenase inhibition with indomethacin (groups 5 and 6), or B 1 R antagonist or vehicle plus blockade of vasoconstricting prostaglandin (PG) H 2 and thromboxane A 2 (TxA 2 ) with SQ29548 (groups 7 and 8). The B 1 R antagonist produced significant (PϽ0.05) blood pressure increases of 17.7Ϯ3.1 mm Hg in group 1 and 10.4Ϯ3 mm Hg in group 3, whereas their vehicle-treated respective control groups 2 and 4 had no significant blood pressure changes. Indomethacin abolished the capacity of the B 1 R antagonist to raise blood pressure, as did blockade of the receptors of PGH 2 and TxA 2 . Injection with the B 1 R agonist produced a hypotensive response (12Ϯ1.3 mm Hg), which was further accentuated by TxA 2 blockade (21.7Ϯ4.1 mm Hg). Analysis of B 1 R gene expression by reverse transcription-polymerase chain reaction (PCR) in cardiac and renal tissues revealed marked expression at baseline, with further upregulation by 1.5-to 2-fold after various manipulations. Expression of the TxA 2 receptor gene in renal tissue by quantitative real-time PCR was significantly lower in mice treated with the B 1 R antagonist, consistent with increased levels of agonist for this receptor. The data confirm that the B 1 R becomes markedly expressed in the absence of B 2 R and suggest that it contributes to vasodilation by inhibiting a vasoconstricting product of the arachidonic acid cascade acting via the PGH 2 /TxA 2 receptor. [3][4][5] whereas their blockade by selective B 2 R antagonists causes a small but significant hypertensive effect. 6 The B 1 Rs are normally not expressed under physiologic conditions but are inducible by inflammation, lipopolysaccharides, cytokines, vascular trauma, etc. 7-9 Once induced, the B 1 Rs also mediate vasodilation. Indeed, the selective B 1 R agonist des-Arg(9)-bradykinin was shown to reduce blood pressure in rabbits pretreated with lipopolysaccharides, but not in controls, 10 and to relax an in vitro preparation of rabbit mesenteric arteries. 11 In previous studies, we have shown that the normally nonexpressed B 1 R gene becomes expressed in B 2 R geneknockout mice, in which the B 1 R assume some of the hemodynamic properties of the B 2 R and is further upregulated in response to hypertensive maneuvers. 12 These findings suggest a role for the B 1 R in vascular tone regulation, but the extent to which these receptors are involved and the mechanism of B 1 R-mediated vasodilation are not clearly understood. The current study was designed to explore this mechanism. For this purpose, we used B 2 R gene-knockout...

Objective: In previous studies using serial analysis of gene expression for elucidation of the molecular pathways of angiotensin II (Ang II)-induced hypertensive/ischemic cardiomyopathy in mice, we found that a hitherto unknown transcript, designated initially as 2310008C07Rik, an unknown expressed sequence tag (EST), was highly significantly upregulated in myocardial tissue. The current experiments were designed to further characterize this gene and to evaluate its expression in various types of hypertension. Methods:Mice rendered hypertensive by Ang II infused intravenously at 30 ng/min for 6 h or by osmotic minipump at 0.9 g/h for 7 or 14 days, were compared to saline-infused normotensive controls and to mice with hypertension induced by subtotal nephrectomy and 1% saline as drinking water. At end point, mice were euthanized, their tissues processed for gene expression analysis, and results were confirmed by ribonuclease protection assay. Results:The Ang II-infused mice developed systolic blood pressure (BP) of 134 Ϯ 7, 158 Ϯ 13, and 149 Ϯ 15 mm Hg at 6 h, 7days, and 14 days, respectively, compared to 102 Ϯ 9, 110 Ϯ 8, and 114 Ϯ 7 mm Hg in their respective controls and subtotally nephrectomized salt-fed mice had end point blood pressure of 153 Ϯ 5 v 112 Ϯ 7 mm Hg in controls. Through sequencing and expression analysis we found that the unknown transcript is part of the cardiomyopathy associated 3 (Cmya3) gene, being overexpressed in Ang II-induced but not salt-induced hypertension. Conclusions:The highly expressed 2310008C07Rik EST was found to be part of Cmya3 and its upregulation is due to Ang II-induced myocardial damage and not to BP elevation per se. Am

Aims  The aim of this study was to determine the contemporary use of reperfusion therapy in the European Society of Cardiology (ESC) member and affiliated countries and adherence to ESC clinical practice guidelines in patients with ST-elevation myocardial infarction (STEMI). Methods and results  Prospective cohort (EURObservational Research Programme STEMI Registry) of hospitalized STEMI patients with symptom onset <24 h in 196 centres across 29 countries. A total of 11 462 patients were enrolled, for whom primary percutaneous coronary intervention (PCI) (total cohort frequency: 72.2%, country frequency range 0–100%), fibrinolysis (18.8%; 0–100%), and no reperfusion therapy (9.0%; 0–75%) were performed. Corresponding in-hospital mortality rates from any cause were 3.1%, 4.4%, and 14.1% and overall mortality was 4.4% (country range 2.5–5.9%). Achievement of quality indicators for reperfusion was reported for 92.7% (region range 84.8–97.5%) for the performance of reperfusion therapy of all patients with STEMI <12 h and 54.4% (region range 37.1–70.1%) for timely reperfusion. Conclusions  The use of reperfusion therapy for STEMI in the ESC member and affiliated countries was high. Primary PCI was the most frequently used treatment and associated total in-hospital mortality was below 5%. However, there was geographic variation in the use of primary PCI, which was associated with differences in in-hospital mortality.