Search

1 To identify the roles of endogenous kinins in prevention of myocardial infarction (MI), we performed the permanent ligation of coronary artery in rats. 2 The size of MI 12, 24, and 48 h after coronary ligation in kininogen-deficient Brown Norway Katholiek (BN-Ka) rats was significantly larger (49.7+/-0.2%, 49.6+/-2%, and 51.1+/-1%, respectively) than that of kinin-replete Brown Norway Kitasato (BN-Ki) rats (42+/-2%, 38.5+/-4%, and 41.5+/-1%). 3 Hoe140, a bradykinin (BK) B(2) receptor antagonist injected (1.0 mg kg(-1), i.v.) half an hour before, and every 8 h after, coronary ligation, significantly increased the size of MI in Sprague-Dawley rats. Aprotinin, a kallikrein inhibitor, which was infused intravenously (10,000 Units kg(-1) h(-1)) with an osmotic mini-pump, significantly increased the size of an MI 24 h after ligation. 4 When evaluated using microspheres, the regional myocardial blood flow around the necrotic lesion in BN-Ka rats 6 h after ligation was reduced more than that in BN-Ki rats with MI by 41-46%. The same was true in Hoe140-treated BN-Ki rats. 5 FR190997, a nonpeptide B(2) agonist, which was infused (10 microg kg(-1) h(-1)) into the vena cava of BN-Ka rats for 24 h with an osmotic mini-pump, caused significant reduction in the size of MI (38+/-3%), in comparison with the size in vehicle solution-treated rats (51+/-3%). The size of MI in FR190997-treated BN-Ka rats was the same as in BN-Ki rats. 6 These results suggested that endogenous kinin has the capacity to reduce the size of MI via B(2) receptor signalling because of the increase in regional myocardial blood flow around the ischaemic lesion.

Physiological roles of angiotensin II type 2 receptor (AT(2)) are not well defined. This study was designed to investigate the mechanisms of AT(2)-dependent vascular relaxation by studying vasodilation in pressurized and perfused rat mesenteric arterial segments. Perfusion of angiotensin II in the presence of AT(1) antagonist elicited vascular relaxation, which was completely dependent on AT(2) receptors on endothelium. FR173657 (>1 microM), a bradykinin (BK) B(2)-specific antagonist, significantly suppressed AT(2)-dependent vasodilation (maximum inhibition: 68.5% at 10 microM). Kininogen-deficient Brown Norway Katholiek rats showed a significant reduction in AT(2)-mediated vasodilatory response compared with normal wild-type Brown Norway rats. Indomethacin (>1 microM), aprotinin (10 microM) and soybean trypsin inhibitor (10 microM) also reduced AT(2)-dependent vasodilation. Our results demonstrated that stimulation of AT(2) receptors caused a significant vasodilation through local production of BK in resistant arteries of rat mesentery in a flow-dependent manner. Such vasodilation counterbalances AT(1)-dependent vasoconstriction to regulate the vascular tone.

1. The involvement of bradykinin (BK) B(2) receptor in acute pancreatitis induced by pancreaticobiliary duct ligation was investigated in rats. 2. The activities of amylase and lipase in the serum, the water content of the pancreas, and vacuolization of the acinar cells were significantly increased 2 h after obstruction of the duct in Sprague-Dawley rats. 3. Elevated serum amylase activity, increased pancreatic oedema, and damage of the pancreatic tissue were significantly less marked in plasma kininogen-deficient, B/N-Katholiek rats than in the normal strain, B/N-Kitasato rats 2 h after the ligation. 4. Obstruction of the pancreaticobiliary duct augmented the level of (1-5)-BK (Arg(1)-Pro(2)-Pro(3)-Gly(4)-Phe(5)), a stable BK metabolite, in the blood from 73.0+/-21.7 pg ml(-1) at 0 h to 149.8+/-38.0 pg ml(-1) at 2 h after the induction of pancreatitis in SD rats. 5. Administration of a BK B(2) receptor antagonist, FR173657 (100 mg kg(-1), p.o.) or Hoe140 (100 nmol kg(-1), s.c.), reduced the elevation of amylase and lipase activities in the serum and of pancreatic water content in a dose-dependent manner. The effective attenuation of oedema formation and vacuolization by the antagonists was also confirmed light-microscopically. In contrast, treatment with gabexate mesilate or indomethacin did not cause significant suppression of the pancreatitis. 6. These findings suggest a possible involvement of kinin B(2) receptor in the present pancreatitis model. Furthermore, they point to the potential usefulness of the B(2) receptor in clinical acute pancreatitis.

1. Proinflammatory potency of the nonpeptide bradykinin (BK) B(2) receptor agonist FR190997 (8-[2,6-dichloro-3-[N-[(E)-4-(N-methylcarbamoyl)cinnamidoacetyl]-N-methylamino]benzyloxy]-2-methyl-4-(2-pyridylmethoxy)quinoline) was investigated. 2. Intradermal injection of FR190997 (0.03 - 3 nmol site(-1)) into dorsal skin of rats increased vascular permeability in a dose-dependent manner. The effect was less than that of BK, but it was long-acting and was inhibited by treatment with FR173657 (3 mg kg(-1), p.o.). Captopril (10 mg kg(-1), i.p.) did not enhance the plasma extravasation by FR190997 (0.3 nmol site(-1)) in the presence of soybean trypsin inhibitor (SBTI, 30 microg site(-1)). 3. Subcutaneous injection of FR190997 (3 nmol site(-1)) into the hindpaw of mice markedly induced paw swelling. The oedema lasted up to 3 h after the injection. Administration of indomethacin or NS-398 (10 mg kg(-1), i.p.) significantly reduced it at 3 h after the injection. 4. Simultaneous i.p. injection of prostaglandin (PG) E(2) (1 nmol site(-1)) or beraprost sodium (0.5 nmol site(-1)) with FR190997 (5 nmol site(-1)) greatly enhanced frequency of writhing reactions in mice. 5. FR190997 (0.3 - 30 nmol kg(-1), i.v.) showed less increase in airway opening pressure (Pao) in the guinea-pig after i.v. injection. Furthermore, FR190997 (0.03 - 30 nmol) resulted in a very weak contraction of tracheal ring strips and lung parenchymal sections in vitro. 6. In mice sponge implants, topical application of FR190997 increased angiogenesis and granulation with enhanced expressions of basic fibroblast growth factor (bFGF) and vascular endothelial growth factor (VEGF) mRNAs. 7. These results indicate that FR190997 has proinflammatory long-lasting characteristics and it might be 'a stable tool' for studying the role of BK B(2) receptor in vivo.

We have previously reported that the renal kallikrein-kinin system suppressed the development of deoxycorticosterone acetate (DOCA)-salt hypertension. Kinins were degraded in the kidney mainly by carboxypeptidase Y (CPY)-like kininase. Blockade of renal kinin degradation may reduce hypertension in the developmental stage. We constructed an antisense oligonucleotide against rat CPY homologue (5'-CAT-CTC-TGC-TTC-CTT-GTG-TC-3', AS) and its randomized control oligonucleotide (5'-TCC-TTC-CTG-CTT-GAG-TTC-CT-3', RC), and prepared an HVJ-liposome complex that prolongs and increases the effectiveness of the antisense oligonucleotide. Antisense oligonucleotide was transfected (25 nmole rat(-1), in terms of nucleotide) into the kidney from the renal artery. Blood pressure was measured through a catheter inserted into the abdominal aorta. Mean blood pressure (MBP) in DOCA-salt treated (for 2 weeks) Sprague Dawley strain rats was 130+/-3 mmHg (n=11), and was reduced significantly (P<0.05) more by AS transfection (122+/-4 mmHg, n=6) than by RC treatment (137+/-6 mmHg, n=5) 4 days after the transfection. This reduction in MBP was accompanied by increased urinary sodium excretion (AS, 8.4+/-1.5 mmole day(-1); RC, 4.6+/-0.5 mmole day(-1), P<0.05) and a reduction in urinary CPY-like kininase activity. Ebelactone B (5 mg kg(-1), twice a day, p.o.), an inhibitor for urinary CPY-like kininase, also reduced MBP and induced natriuresis to the same degree as AS. Lisinopril, an inhibitor for angiotensin converting enzyme (ACE) failed to reduce the elevated MBP. These results suggest that CPY-like kininase may have more contribution than ACE to degrade kinin in the kidney, and that knockdown of CPY-like kininase in the kidney may partly prevent rat DOCA-salt hypertension.

Angiogenesis is reportedly enhanced by prostaglandins (PGs). In the present study, we investigated whether or not cyclo-oxygenase (COX)-2 mediated angiogenesis in chronic and proliferate granuloma. In rat sponge implants, angiogenesis was gradually developed over a 14-day experimental period as granuloma formed. This angiogenesis was enhanced by topical injections of human recombinant basic fibroblast growth factor (bFGF). In sponge granuloma, mRNA of COX-1 was constitutively expressed, whereas that of COX-2 was increased with neovascularization in parallel with that of vascular endothelial growth factor (VEGF). Topical injections of bFGF increased the expression of COX-2 mRNA. bFGF-stimulated angiogenesis was inhibited by indomethacin or selective COX-2 inhibitors, NS-398, nimesulide, and JTE-522. The levels of PGE(2) and 6-keto-PGF(1alpha) in the sponge granuloma were increased with bFGF 13 fold and 9 fold, respectively, and these levels were markedly reduced by NS-398. The expression of VEGF mRNA in the granuloma was also enhanced by bFGF, and was reduced by NS-398. Topical injections of PGE(2) and beraprost sodium, a PGI(2) analogue, increased the expression of VEGF mRNA, with angiogenesis enhancement. The enhanced angiogenesis by bFGF was significantly inhibited by topical injections of VEGF anti-sense oligonucleotide. These results suggested that COX-2 may enhance bFGF-induced neovascularization in sponge granuloma by PG-mediated expression of VEGF, and that a COX-2 inhibitor would facilitate the management of conditions involving angiogenesis.

The effect of prolonged administration of a carboxypeptidase Y-like kininase inhibitor, ebelactone B (EB) (2-ethyl-3, 11-dihydroxy-4, 6, 8, 10, 12-pentamethyl-9-oxo-6-tetradecenoic 1, 3-lactone), on the development of deoxycorticosterone acetate (DOCA)-salt hypertension was tested. The systolic blood pressure (SBP) of non-treated 6-week-old Sprague-Dawley strain rats was gradually increased by DOCA-salt treatment from 137+/-2 mmHg (n=11) to 195+/-7 mmHg at 10 weeks of age. With daily oral administration of lisinopril (5 mg kg(-1), twice a day), which is an inhibitor of angiotensin converting enzyme, a major kininase in plasma, the development of hypertension was not suppressed. By contrast, administration of EB (5 mg kg(-1), twice a day), completely inhibited the development of hypertension (SBP: 146+/-1 mmHg, n=5, 10 weeks old). The reduced SBP at 10 weeks of age was equal to the SBP before any treatment (142+/-1 mmHg, n=5). Direct determination of mean blood pressure (MBP) in conscious, unrestrained rats confirmed that MBP elevation was completely inhibited by EB. Continuous subcutaneous infusion (5 mg kg(-1) day(-1)) of HOE140, a bradykinin B2 receptor antagonist, restored the elevation of SBP, which was suppressed by EB. The weights of left ventricle of DOCA-salt treated rats 10-weeks-old (0.36+/-0.02 g 100 g body weight(-1), n=11) was significantly reduced by EB (0.27+/-0.01, n=5), as were the sodium levels in serum, cerebrospinal fluid and erythrocyte. These findings suggested that EB is effective in preventing salt-related hypertension presumably by eliminating sodium retention.

1. Subcutaneous injection of sodium deoxycholic acid into the anterior of the back of male ddY mice elicited dose-dependent scratching of the injected site with the forepaws and hindpaws. 2. Up to 100 microg of sodium deoxycholic acid induced no significant increase in vascular permeability at the injection site as assessed by a dye leakage method. 3. Bradykinin (BK) B2 receptor antagonists, FR173657 and Hoe140, significantly decreased the frequency of scratching induced by sodium deoxycholic acid. 4. Treatment with aprotinin to inhibit tissue kallikrein reduced the scratching behaviour induced by sodium deoxycholic acid, whereas treatment with soybean trypsin inhibitor to inhibit plasma kallikrein did not. 5. Although injection of kininase II inhibitor, lisinopril together with sodium deoxycholic acid did not alter the scratching behaviour, phosphoramidon, a neutral endopeptidase inhibitor, significantly increased the frequency of scratching. 6. Homogenates of the skin excised from the backs of mice were subjected to gel-filtration column chromatography followed by an assay of kinin release by trypsin from each fraction separated. Less kinin release from the fractions containing kininogen of low molecular weight was observed in the skin injected with sodium deoxycholic acid than in normal skin. 7. The frequency of scratching after the injection of sodium deoxycholic acid in plasma kininogen-deficient Brown Norway Katholiek rats was significantly lower than that in normal rats of the same strain, Brown Norway Kitasato rats. 8. These results indicate that BK released from low-molecular-weight kininogen by tissue kallikrein, but not from high-molecular-weight kininogen by plasma kallikrein, may be involved in the scratching behaviour induced by the injection of sodium deoxycholic acid in the rodent.

1. Effects of an orally active non-peptide (BK) B2 receptor antagonist, FR173657 ((E)-3-(6-acetamido-3-pyridyl)-N-[N-[2,4-dichloro-3-[(2-methyl-8-quinoli nyl) oxymethyl]phenyl]-N-methylaminocarbonylmethyl] acrylamide) on the plasma exudation in rat carrageenin-induced pleurisy were investigated. 2. Plasma exudation induced by intrapleural injection of bradykinin (BK, 3 nmol per rat) into male SD strain rats (SPF, 8 weeks old) were significantly inhibited by oral administration of novel B2 receptor antagonist FR173657 (3-30 mg kg-1, 1 h before BK injection) in a dose-dependent manner, whereas that induced by histamine was not. 3. The inhibitory effect of 30 mg kg-1 FR173657 persisted for more than 4 h. 4. Intrapleural injection of lambda-carrageenin (2% (w/v), 0.1 ml per rat) caused marked plasma exudation and accumulation of exudates from 1 h after carrageenin injection. The maximum plasma exudation response was observed 5 h after carrageenin. The oral administration of FR173657 to rats (30 mg kg-1, 1 h before carrageenin) significantly (by 50-77%) blunted the plasma exudation 1, 3, 5, and 7 h after carrageenin, causing a significant parallel reduction (by 42-57%) in the volume of exudates. 5. The anti-inflammatory effect of FR173657 on rat carrageenin-induced pleurisy was almost equipotent with that of the peptide B2 antagonist Hoe140 (1 mg kg-1, i.v.), a plasma kallikrein inhibitor, soy bean trypsin inhibitor (0.3 mg per rat, intrapleural injection) and bromelain (10 mg kg-1, i.v.). 6. In pleurisy induced by intrapleural injection of a histamine releaser, compound 48/80, the plasma exudation was observed only within 20 min after the injection. This plasma exudation was not affected by FR173657, although it was completely inhibited by a mixture of pyrilamine (5 mg kg-1, i.v.) and methysergide (3 mg kg-1, i.v.). 7. These results indicate that FR173657 is an orally active, promising anti-inflammatory agent for kinin-dependent inflammation.

1. Intravenous administration of leukotriene C4 (LTC4) and LTD4 (1-10 nmol kg-1) caused a dose-dependent increase in secretion of glandular-kallikrein in the bronchial washings of guinea-pigs, as measured by cleavage of a synthetic substrate and the formation of kinin. LTC4 was more potent than LTD4 and pilocarpine was much less potent than peptide leukotrienes on a molecular basis. 2. The increases in levels of glandular-kallikrein in the bronchial washings that were induced by LTC4 (3 nmol kg-1, i.v.) were almost completely inhibited by pretreatment with an antagonist of leukotrienes (ONO-1078), with an antagonist of thromboxane (S-1452), with an inhibitor of thromboxane synthetase (OKY-046), with indomethacin, with atropine or with scopolamine. These results indicate that the LTC4-induced increase in levels of glandular-kallikrein may have been mediated by the formation of thromboxane and the release of acetylcholine. 3. The increases in levels of glandular-kallikrein in the bronchial washings induced by STA2 (20 pmol kg-1, i.v.), a stable analogue of thromboxane A2, were completely blocked by pretreatment with atropine, whereas increases induced by pilocarpine (41 mumol kg-1, i.v.) were not blocked by pretreatment with indomethacin, although such increases were inhibited by atropine. This result indicates that secretion of kallikrein stimulated by LTC4 may have been mediated by the successive formation of thromboxane A2 and release of acetylcholine. 4. Intravenous administration of bradykinin (3-30 nmol kg-1) caused a dose-dependent increase in levels of glandular-kallikrein in the bronchial washings. This increase was completely inhibited by pretreatment with atropine, with indomethacin or with an antagonist of thromboxane.5. The increases in levels of glandular-kallikrein in the bronchial washings induced by LTC4 (3 nmol kg'- , i.v.) and pilocarpine (41 flmol kg- 1, i.v.) were significantly inhibited by pretreatment with an antagonist of bradykinin. These results suggest that intravenous LTC4 may increase secretion of glandular-kallikrein via formation of thromboxane A2 and release of acetylcholine in that order, and kinin released by kallikrein may enhance the rate of secretion of glandular-kallikrein.

1. In vitro incubation of normal rat plasma with endotoxin from E. coli (3-10 mg ml-1) in the incubation mixture) caused a dose-dependent increase in levels of free kinin and plasma kallikrein in the presence of o-phenanthroline, together with a mirror-image, dose-dependent decrease in the residual levels of the precursors, plasma prekallikrein and high-molecular-weight kininogen. Low-molecular-weight kininogen levels were not modified. 2. Intravenous injection of endotoxin (3-30 mg kg-1) into the femoral vein of anaesthetized rats resulted in dose-dependent hypotension. In blood collected up to 15 min after injection, the levels of prekallikrein and high-molecular-weight kininogen in plasma were decreased while levels of the active forms, plasma kallikrein and free kinin, showed a transient increase in the blood 1 min after administration of endotoxin. 3. A degradation product of bradykinin, des-Phe8-Arg9-bradykinin, as measured by a newly developed enzyme immunoassay, was detectable up to 5 min after administration of endotoxin. 4. Intravenous infusion of soybean trypsin inhibitor inhibited both the formation of bradykinin and des-Phe8-Arg9-bradykinin and the initial hypotension. 5. It can be concluded from our results that plasma prekallikrein is activated in the blood immediately after administration of endotoxin to rats and that bradykinin is a major cause of the immediate hypotension.