Cleaved high molecular weight kininogen inhibits tube formation of endothelial progenitor cells via suppression of matrix metalloproteinase 2

Anti-HK antibody reveals critical roles of a 20-residue HK region for Aβ-induced plasma contact system activation

Alzheimer's disease (AD) is a neurodegenerative disorder and the leading cause of dementia. Vascular abnormalities and neuroinflammation play roles in AD pathogenesis. Plasma contact activation, which leads to fibrin clot formation and bradykinin release, is elevated in many AD patients, likely due to the ability of AD's pathogenic peptide β-amyloid (Aβ) to induce its activation. Since overactivation of this system may be deleterious to AD patients, the development of inhibitors could be beneficial. Here, we show that 3E8, an antibody against a 20-amino acid region of high molecular weight kininogen's (HK) domain 6, inhibits Aβ-induced intrinsic coagulation. Mechanistically, 3E8 inhibits contact system activation by blocking the binding of prekallikrein (PK) and factor XI (FXI) to HK, thereby preventing their activation and the continued activation of factor XII (FXII). The 3E8 antibody can also disassemble HK/PK and HK/FXI complexes in normal human plasma in the absence of a contact system activator due to its strong binding affinity for HK, indicating its prophylactic ability. Furthermore, the binding of Aβ to both FXII and HK is critical for Aβ-mediated contact system activation. These results suggest that a 20-amino acid region of HK's domain 6 plays a critical role in Aβ-induced contact system activation, and this region may provide an effective strategy to inhibit or prevent contact system activation in related disorders.

Intratracheal transplantation of endothelial progenitor cells attenuates smoking-induced COPD in mice

Background

Endothelial progenitor cells (EPCs) might play a protective role in COPD. The aim of this study was to investigate whether intratracheal allogeneic transplantation of bone-marrow-derived EPCs would attenuate the development of smoking-induced COPD in mice.

Methods

Isolated mononuclear cells from the bone marrow of C57BL/6J mice were cultured in endothelial cell growth medium-2 for 10 days, yielding EPCs. A murine model of COPD was established by passive 90-day exposure of cigarette smoke. On day 30, EPCs or phosphate-buffered saline alone was administered into the trachea. On day 90, EPCs or 30 μL phosphate-buffered saline alone was administered into the trachea, and on day 120, inflammatory cells, antioxidant activity, apoptosis, matrix metalloproteinase (MMP)-2, and MMP-9 were measured.

Results

After EPC treatment, the lung function of the mice had improved compared with the untreated mice. Mean linear intercept and destructive index were reduced in the EPCs-treated group compared with the untreated group. In addition, the EPCs-treated mice exhibited less antioxidant activity in bronchoalveolar lavage fluid compared with the untreated mice. Moreover, decreased activities of MMP-2, MMP-9, and TUNEL-positive cells in lung tissues were detected in EPCs-treated mice.

Conclusion

Intratracheal transplantation of EPCs attenuated the development of pulmonary emphysema and lung function disorder probably by alleviating inflammatory infiltration, decelerating apoptosis, inhibiting proteolytic enzyme activity, and improving antioxidant activity.

A stromal interaction molecule 1 variant up-regulates matrix metalloproteinase-2 expression by strengthening nucleoplasmic Ca2+ signaling

Very recent studies hold promise to reveal the role of stromal interaction molecule 1 (STIM1) in non-store-operated Ca2+ entry. Here we showed that in contrast to cytoplasmic membrane redistribution as previously noted, human umbilical vein endothelial STIM1 with a T-to-C nucleotide transition resulting in an amino acid substitution of leucine by proline in the signal peptide sequence translocated to perinuclear membrane upon intracellular Ca2+ depletion, amplified nucleoplasmic Ca2+ signaling through ryanodine receptor-dependent pathway, and enhanced the subsequent cAMP responsive element binding protein activity, matrix metalloproteinase-2 (MMP-2) gene expression, and endothelial tube forming. The abundance of mutated STIM1 and the MMP-2 expression were higher in native human umbilical vein endothelial cells of patients with gestational hypertension than controls and were significantly correlated with blood pressure. These findings broaden our understanding about structure-function bias of STIM1 and offer unique insights into its application in nucleoplasmic Ca2+, MMP-2 expression, endothelial dysfunction, and pathophysiological mechanism(s) of gestational hypertension.

Contact pathway of coagulation and inflammation

The contact system, also named as plasma kallikrein-kinin system, consists of three serine proteinases: coagulation factors XII (FXII) and XI (FXI), and plasma prekallikrein (PK), and the nonenzymatic cofactor high molecular weight kininogen (HK). This system has been investigated actively for more than 50 years. The components of this system and their interactions have been elucidated from in vitro experiments, which indicates that this system is prothrombotic by activating intrinsic pathway, and proinflammatory by producing bioactive peptide bradykinin. Although the activation of the contact system have been implicated in various types of human disease, in only a few instances is its role clearly defined. In the last 10 years, our understanding of the contact system, particularly its biology and (patho)physiology has greatly increased through investigations using gene-modified animal models. In this review we will describe a revitalized view of the contact system as a critical (patho)physiologic mediator of coagulation and inflammation.

Hyperhomocysteinemia suppresses bone marrow CD34+/VEGF receptor 2+ cells and inhibits progenitor cell mobilization and homing to injured vasculature-a role of β1-integrin in progenitor cell migration and adhesion

Hyperhomocysteinemia (HHcy) impairs re-endothelialization and accelerates vascular remodeling. The role of CD34(+)/VEGF receptor (VEGFR) 2(+) progenitor cells (PCs) in vascular repair in HHcy is unknown. We studied the effect of HHcy on PCs and its role in vascular repair in severe HHcy (∼150 μM), which was induced in cystathionine-β synthase heterozygous mice fed a high-methionine diet for 8 weeks. Vascular injury was introduced by carotid air-dry endothelium denudation. CD34(+)/VEGFR2(+) cells were examined by flow cytometry. HHcy reduced bone marrow (BM) CD34(+)/VEGFR2(+) cells and suppressed replenishment of postinjury CD34(+)/VEGFR2(+) cells in peripheral blood (PB). Donor green fluorescent protein-positive PC homing to the injured vessel was reduced in HHcy after CD34(+) PCs from enhanced green fluorescent protein mice were adoptively transferred following carotid injury. CD34(+) PC transfusion partially reversed HHcy-suppressed re-endothelialization and HHcy-induced neointimal formation. Furthermore, homocysteine (Hcy) inhibited proliferation, adhesion, and migration and suppressed β1-integrin expression and activity in human CD34(+) endothelial colony-forming cells (ECFCs) isolated from PBs in a dose-dependent manner. A functional-activating β1-integrin antibody rescued Hcy-suppressed adhesion and migration in CD34(+) ECFCs. In conclusion, HHcy reduces BM CD34(+)/VEGFR2(+) generation and suppresses CD34(+)/VEGFR2(+) cell mobilization and homing to the injured vessel via β1-integrin inhibition, which partially contributes to impaired re-endothelialization and vascular remodeling.

Novel role of kallistatin in vascular repair by promoting mobility, viability, and function of endothelial progenitor cells

Background

Kallistatin exerts pleiotropic activities in inhibiting inflammation, apoptosis, and oxidative stress in endothelial cells. Because endothelial progenitor cells (EPCs) play a significant role in vascular repair, we investigated whether kallistatin contributes to vascular regeneration by enhancing EPC migration and function.

Methods and Results

We examined the effect of endogenous kallistatin on circulating EPCs in a rat model of vascular injury and the mechanisms of kallistatin on EPC mobility and function in vitro. In deoxycorticosterone acetate–salt hypertensive rats, we found that kallistatin depletion augmented glomerular endothelial cell loss and diminished circulating EPC number, whereas kallistatin gene delivery increased EPC levels. In cultured EPCs, kallistatin significantly reduced tumor necrosis factor‐α–induced apoptosis and caspase‐3 activity, but kallistatin's effects were blocked by phosphoinositide 3‐kinase inhibitor (LY294002) and nitric oxide (NO) synthase inhibitor (l‐NAME). Kallistatin stimulated the proliferation, migration, adhesion and tube formation of EPCs; however, kallistatin's actions were abolished by LY294002, l‐NAME, endothelial NO synthase–small interfering RNA, constitutively active glycogen synthase kinase‐3β, or vascular endothelial growth factor antibody. Kallistatin also increased Akt, glycogen synthase kinase‐3β, and endothelial NO synthase phosphorylation; endothelial NO synthase, vascular endothelial growth factor, and matrix metalloproteinase‐2 synthesis and activity; and NO and vascular endothelial growth factor levels. Kallistatin's actions on phosphoinositide 3‐kinase–Akt signaling were blocked by LY294002, l‐NAME, and anti–vascular endothelial growth factor antibody.

Conclusions

Endogenous kallistatin plays a novel role in protection against vascular injury in hypertensive rats by promoting the mobility, viability, and vasculogenic capacity of EPCs via enhancing NO and vascular endothelial growth factor levels through activation of phosphoinositide 3‐kinase–Akt signaling. Kallistatin therapy may be a promising approach in the treatment of vascular diseases.

Cleaved high molecular weight kininogen stimulates JNK/FOXO4/MnSOD pathway for induction of endothelial progenitor cell senescence

OBJECTIVE

Recently we have reported that cleaved high molecular weight kininogen (HKa) accelerates the onset of endothelial progenitor cells (EPCs) senescence by induction of reactive oxygen species (ROS). However, the mechanisms by which HKa induces production of ROS remain unknown. In this study, we have shown that HKa induces EPC senescence via stimulation of c-Jun N-terminal kinases (JNK)-related pathway.

METHODS AND RESULTS

Treatment of human EPCs with HKa for 72h stimulated JNK phosphorylation at Thr183/Tyr185, and FOXO4 phosphorylation at Thr451, Concomitantly, upregulated the expression of MnSOD at protein and mRNA levels in a concentration-dependent manner. HKa increased intracellular level of H2O2, without affecting the expression of catalase. To narrow down the functional domain of HKa, recombinant proteins of human HK heavy chain (HC, 19-380aa) and light chain (LC, 390-644aa) were generated. HC, but not LC, increased senescence of EPCs and intracellular ROS levels, to a similar extent with HKa. Moreover, HC at 50 nM increased FOXO4 phosphorylation at Thr451 and the protein level of MnSOD in EPCs.

CONCLUSION

These results demonstrate that HKa accelerates the onset of EPC senescence by stimulating JNK/FOXO4/MnSOD pathway, its effect is mediated by the HC.

Influence of growth factors and cytokines on angiogenic function of endothelial progenitor cells: a review of in vitro human studies

Growth factors and cytokines released at sites of injury and inflammation play an important role in stimulating endothelial progenitor cell (EPC) migration to these sites. A comparative analysis of the literature shows under neutral in vitro conditions (pH 7.4), several growth factors and cytokines influenced favorably indices of EPC angiogenic function. They included SDF-1, VEGF, PlGF, FGF-2, NGF and IL-1β. Others, e.g. TNF-α, have an unfavorable influence. SDF-1 and VEGF in combination increased chemotactic cell migration and reduced apoptosis caused by serum starvation. Under acidic conditions (pH 6.5), the biological activity of certain growth factors may be impaired, although TPO, SCF and IL-3 were each able to rescue EPCs from acidic exposure apoptosis, a combination of these three factors stimulated cell proliferation and prevented apoptosis. Possible combinations of growth factors and cytokines together with EPC transplantation may provide for a greater extent of vessel repair and new vessel formation.

Endothelial colony-forming cells derived from pregnancies complicated by intrauterine growth restriction are fewer and have reduced vasculogenic capacity

CONTEXT

Endothelial colony-forming cells (ECFCs) are the only putative endothelial progenitor cells capable of vasculogenesis, and their dysfunction may represent a risk factor for cardiovascular disease. Intrauterine growth restriction (IUGR) is a pregnancy-related disorder associated with long-term cardiovascular risk.

OBJECTIVE

Our objective was to determine whether ECFCs derived from pregnancies complicated by IUGR exhibit altered vasculogenic potential.

DESIGN AND SETTING

This was a prospective cohort study; patients were recruited at St. Mary's Hospital, Manchester, United Kingdom.

PARTICIPANTS

Twenty-three women with normal pregnancies and 13 women with IUGR-complicated pregnancies at gestational ages above 37 weeks were included.

MAIN OUTCOME MEASURES

Vasculogenic capacity of rigorously characterized ECFCs was investigated in vivo by measuring blood vessel formation in collagen/fibronectin gels implanted in mice; proliferative, migratory, and chemotactic abilities were assessed in cell culture. Placental uptake of fetal ECFCs, assessed by differences in arterial and venous cord blood content, was determined by flow cytometry.

RESULTS

In vivo, IUGR ECFCs formed fewer blood vessels (P < .001) and capillaries (P = .001) compared with normal pregnancy-derived ECFCs. In culture conditions, IUGR ECFCs had reduced proliferation (P = .01) and migration (P = .007) and diminished chemotactic abilities to stromal cell-derived factor 1 (P = .007) coupled with reduced hypoxia-induced matrix metalloproteinase-2 release (P = .02). Finally, in IUGR pregnancies, the number of ECFCs was lower in arterial cord blood (P = .002) and placental uptake of cells was reduced (P < .001).

CONCLUSIONS

ECFCs derived from IUGR cord blood are rarefied and dysfunctional, resulting in diminished vasculogenic potential; this could be a cause of placental dysfunction in IUGR, with long-term postnatal implications for cardiovascular function in offspring.

Kallikrein gene-modified EPCs induce angiogenesis in rats with ischemic hindlimb and correlate with integrin αvβ3 expression

Background

Human tissue kallikrein (hTK) plays an essential role in the physiological and pathological mechanisms of blood vessels. This study aimed to determine whether angiogenesis induced by endothelial progenitor cells (EPCs) transduced with the adenovirus-mediated hTK gene could improve blood flow in rat hindlimb ischemia in vivo and to establish a promising mechanism in vitro.

Methods

EPCs transduced with adenovirus encoding hTK-162 (i.e., Ad/hTK-transduced EPCs or Ad/GFP-transduced EPCs) were administered to Wister rats with hindlimb ischemia through therapeutic neovascularization. Muscular capillary density (MCD), blood flow (BF), and the number of myofibers were measured at days 7, 14, and 21 after treatment. Expressions of integrin αvβ3 and endothelial nitric oxide synthase (eNOS) were detected on the surface of EPCs.

Results

MCD, BF, and the number of myofibers in rats with Ad/hTK-transduced EPCs remarkably increased at day 21 after treatment compared with rats with Ad/GFP-transduced EPCs or the control group (P<0.01). Expressions of integrin αvβ3 and eNOS protein on the surface of EPCs also increased in rats with Ad/hTK-transduced EPCs. The levels of integrin αvβ3 expression were reduced by PI3K and eNOS blockade, and the inhibitor of integrin αvβ3 abrogated the migration and adhesion of hTK-transduced EPCs (P<0.05).

Conclusion

hTK gene delivery in vivo improves the natural angiogenic response to ischemia. The ability of hTK gene-transduced EPCs can be enhanced in vitro, in which integrin αvβ3 plays a role in the process.

Role of plasma kallikrein-kinin system activation in synovial recruitment of endothelial progenitor cells in experimental arthritis

OBJECTIVE

To examine whether activation of the plasma kallikrein-kinin system (KKS) mediates synovial recruitment of endothelial progenitor cells (EPCs) in arthritis.

METHODS

EPCs were isolated from Lewis rat bone marrow, and expression of progenitor cell-lineage markers and functional properties were characterized. EPCs were injected intravenously into Lewis rats with arthritis, and their recruitment and formation of de novo blood vessels in inflamed synovium were evaluated. The role of plasma KKS was examined using a plasma kallikrein inhibitor (EPI-KAL2) and an antikallikrein antibody (13G11). A transendothelial migration assay was used to determine the role of bradykinin and its receptor in EPC mobilization.

RESULTS

EPCs from Lewis rats exhibited a strong capacity to form tubes and vacuoles and expressed increased levels of bradykinin type 2 receptor (B2R) and progenitor cell markers CD34 and Sca-1. In Lewis rats with arthritis, EPCs were recruited into inflamed synovium at the acute phase of disease and formed de novo blood vessels. Inhibition of plasma kallikrein by EPI-KAL2 and 13G11 significantly suppressed synovial recruitment of EPCs and hyperproliferation of synovial cells. Bradykinin stimulated transendothelial migration of EPCs in a concentration-dependent manner. This was mediated by B2R, as demonstrated by the finding that knockdown of B2R with silencing RNA completely blocked bradykinin-stimulated transendothelial migration. Moreover, bradykinin selectively up-regulated expression of the homing receptor CXCR4 in EPCs.

CONCLUSION

These observations demonstrate a novel role of plasma KKS activation in the synovial recruitment of EPCs in arthritis, acting via kallikrein activation and B2R-dependent mechanisms. B2R might be involved in the mobilization of EPCs via up-regulation of CXCR4.

Endothelial progenitor cells: current development of their paracrine factors in cardiovascular therapy

Endothelial progenitor cells were initially considered to radically alter the concepts of adult tissue angiogenesis for their contribution of incorporation into new blood vessels. Nevertheless, controversy arises over their mechanism of action due to rare cell population and decreased number and impaired activity under pathological changes. Recent studies show that endothelial progenitor cells also function in a paracrine manner by secreting multiple cytokines and growth factors, but the beneficial paracrine signals remain partially unidentified. In this review, we provide an overview of varieties and signal pathways of factors secreted by endothelial progenitor cells and further present the prospect of new ways to encourage cardiovascular protection such as neovascularization, reendothelialization of larger vessels, and myocardial remodeling based on the paracrine factors.

Anti-angiogenic and tumor-suppressive roles of candidate tumor-suppressor gene, Fibulin-2, in nasopharyngeal carcinoma

Fibulin-2 (FBLN2) has been identified as a candidate tumor-suppressor gene in nasopharyngeal carcinoma (NPC). Originally identified through a chromosome 3 NotI genomic microarray screen, it shows frequent deletion or methylation in NPC. FBLN2 is located on chromosome 3p25.1 and is associated with tumor development through its important interactions with the extracellular matrix (ECM) proteins. FBLN2 encodes two isoforms. The short isoform (FBLN2S) is expressed abundantly in normal tissues, but is dramatically downregulated in NPC, while the long isoform (FBLN2L) is either not detectable or is expressed only at low levels in both normal and tumor tissues. Reintroduction of this FBLN2S inhibited cell proliferation, migration, invasion and angiogenesis in vitro. Furthermore, in vivo studies in nude mice show its expression is associated with tumor and angiogenesis suppression. FBLN2-associated angiogenesis occurs via concomitant downregulation of vascular endothelial growth factor and matrix metalloproteinase 2. This study provides compelling evidence that FBLN2S has an important tumor-suppressive and anti-angiogenic role in NPC.

Cleaved high-molecular-weight kininogen accelerates the onset of endothelial progenitor cell senescence by induction of reactive oxygen species

OBJECTIVE

Cleaved high-molecular-weight kininogen (HKa), an activation product of the plasma kallikrein-kinin system, inhibits endothelial cell functions. We questioned whether HKa affects the function of endothelial progenitor cells (EPCs) and accelerates their senescence.

METHODS AND RESULTS

Treatment with HKa for 2 weeks markedly inhibited the formation of large colonies and proliferation of EPCs on collagen surfaces, whereas HKa did not affect collagen-mediated EPC adhesion and survival. Concomitantly, treated EPCs displayed flattened and giant cell morphological changes and formation of intracellular vacuoles. As determined by acidic β-galactosidase staining, HKa increased senescent EPCs by 2- and >3-fold after culture for 1 and 2 weeks, respectively. In addition, HKa suppressed the telomerase activity of EPCs. HKa concentration-dependently increased the generation of intracellular reactive oxygen species (ROS) and markedly upregulated p38 kinase phosphorylation and prosenescence molecule p16(INK4a) expression. SB203580, a p38 inhibitor, attenuated the level of HKa-enhanced p16(INK4a) expression. Either quenching of ROS or inhibition of p38 kinase prevented HKa-induced EPC senescence.

CONCLUSIONS

HKa accelerates the onset of EPC senescence by activating the ROS-p38 kinase-p16(INK4a) signaling cascade. This novel activity of HKa points out the likelihood of HKa serving as an endogenous inducer of EPC senescence.

Highly selective hydrolysis of kinins by recombinant prolylcarboxypeptidase

We have previously cloned a cDNA encoding human prolylcarboxypeptidase (PRCP) and expressed the cDNA in the Schneider 2 (S2) drosophila cell line. Here, we further characterized this recombinant enzyme. Investigations were performed to determine whether recombinant PRCP (rPRCP) metabolizes kinins (BK 1-9 and BK 1-8). The metabolites of these kinins were identified by LC/MS. rPRCP metabolized BK 1-8 to BK 1-7, whereas rPRCP was ineffective in metabolizing BK 1-9. The hydrolysis of BK 1-8 by rPRCP was dose- and time-dependent. A homology model of PRCP was developed based upon the sequence of dipeptidyl-peptidase 7 (DPP7, PDB ID: 3JYH), and providentially, the structure of PRCP (PDB ID: 3N2Z) was characterized during the course of our investigation. Docking studies of bradykinin oligopeptides were performed both from the homology model, and from the crystal structure of PRCP. These docking studies may provide a better understanding of the contribution of specific residues involved in substrate selectivity of human PRCP.

Regulation of matrix metalloproteinase activity in health and disease

The activity of matrix metalloproteinases (MMPs) is regulated at several levels, including enzyme activation, inhibition, complex formation and compartmentalization. Regulation at the transcriptional level is also important, although this is not a subject of the present minireview. Most MMPs are secreted and have their function in the extracellular environment. This is also the case for the membrane-type MMPs (MT-MMPs). MMPs are also found inside cells, both in the nucleus, cytosol and organelles. The role of intracellular located MMPs is still poorly understood, although recent studies have unraveled some of their functions. The localization, activation and activity of MMPs are regulated by their interactions with other proteins, proteoglycan core proteins and/or their glycosaminoglycan chains, as well as other molecules. Complexes formed between MMPs and various molecules may also include interactions with noncatalytic sites. Such exosites are regions involved in substrate processing, localized outside the active site, and are potential binding sites of specific MMP inhibitors. Knowledge about regulation of MMP activity is essential for understanding various physiological processes and pathogenesis of diseases, as well as for the development of new MMP targeting drugs.

Targeting stem cell niches and trafficking for cardiovascular therapy

Regenerative cardiovascular medicine is the frontline of 21st-century health care. Cell therapy trials using bone marrow progenitor cells documented that the approach is feasible, safe and potentially beneficial in patients with ischemic disease. However, cardiovascular prevention and rehabilitation strategies should aim to conserve the pristine healing capacity of a healthy organism as well as reactivate it under disease conditions. This requires an increased understanding of stem cell microenvironment and trafficking mechanisms. Engagement and disengagement of stem cells of the osteoblastic niche is a dynamic process, finely tuned to allow low amounts of cells move out of the bone marrow and into the circulation on a regular basis. The balance is altered under stress situations, like tissue injury or ischemia, leading to remarkably increased cell egression. Individual populations of circulating progenitor cells could give rise to mature tissue cells (e.g. endothelial cells or cardiomyocytes), while the majority may differentiate to leukocytes, affecting the environment of homing sites in a paracrine way, e.g. promoting endothelial survival, proliferation and function, as well as attenuating or enhancing inflammation. This review focuses on the dynamics of the stem cell niche in healthy and disease conditions and on therapeutic means to direct stem cell/progenitor cell mobilization and recruitment into improved tissue repair.

A Novel Category of Anti-Hypertensive Drugs for Treating Salt-Sensitive Hypertension on the Basis of a New Development Concept

Terrestrial animals must conserve water and NaCl to survive dry environments. The kidney reabsorbs 95% of the sodium filtered from the glomeruli before sodium reaches the distal connecting tubules. Excess sodium intake requires the renal kallikrein-kinin system for additional excretion. Renal kallikrein is secreted from the distal connecting tubule cells of the kidney, and its substrates, low molecular kininogen, from the principal cells of the cortical collecting ducts (CD). Formed kinins inhibit reabsorption of NaCl through bradykinin (BK)-B₂ receptors, localized along the CD. Degradation pathway of BK by kinin-destroying enzymes in urine differs completely from that in plasma, so that ACE inhibitors are ineffective. Urinary BK is destroyed mainly by a carboxypeptidase-Y-like exopeptidase (CPY) and partly by a neutral endopeptidase (NEP). Inhibitors of CPY and NEP, ebelactone B and poststatin, respectively, were found. Renal kallikrein secretion is accelerated by potassium and ATP-sensitive potassium (KATP) channel blockers, such as PNU-37883A. Ebelactone B prevents DOCA-salt hypertension in rats. Only high salt intake causes hypertension in animals deficient in BK-B2 receptors, tissue kallikrein, or kininogen. Hypertensive patients, and spontaneously hypertensive rats, excrete less kallikrein than normal subjects, irrespective of races, and become salt-sensitive. Ebelactone B, poststatin, and KATP channel blockers could become novel antihypertensive drugs by increase in urinary kinin levels. Roles of kinin in cardiovascular diseases were discussed.