Makoto Katori

High sensitivity to salt in kininogen-deficient brown Norway Katholiek rats.

Brown Norway Katholiek rats, which have very low levels of plasma kininogens, excreted a much smaller amount of kinin in the urine than normal rats of the same strain. The systolic blood pressure of 7-week-old kininogen-deficient rats fed low (0.3%) NaCl diets (131 +/- 4 mm Hg, n = 12) was not different from that in normal rats. Two percent NaCl diets given from 7 weeks of age for 4 weeks caused rapid increases in blood pressure (167 +/- 4 mm Hg, n = 12, 9 weeks old) in deficient rats, although the same diets induced no blood pressure increase in normal rats. Urinary excretion of active kallikrein and prokallikrein remained constant in both rat groups throughout NaCl loading. During this period, the deficient rats secreted less urine (9 weeks old, P < .05) and less urinary sodium (11 weeks old, P < .05). Serum levels of sodium in deficient rats were higher (P < .05) than in normal rats at 9 weeks of age. Intracellular concentrations of sodium in the erythrocytes of deficient rats were higher (P < .05) than in normal rats throughout NaCl loading. Subcutaneous infusion of bovine low molecular weight kininogen with an osmotic pump in NaCl-loaded deficient rats induced a reduction (P < .01) in blood pressure and increases (P < .05) in urine volume and urinary sodium and kinin levels. By contrast, subcutaneous infusion of the bradykinin antagonist Hoe 140 or of aprotinin in NaCl-loaded normal rats induced a hypertensive response. This antagonist treatment reduced urine volume and urinary sodium. These results indicate that the lack of kinin generation observed in the kininogen-deficient rats was related through sodium retention to the hypertensive response to NaCl loading.

Role of prostaglandin H synthase-2 in prostaglandin E2 formation in rat carrageenin-induced pleurisy

Rat carrageenin-induced pleurisy was used to clarify the role of prostaglandin H synthase (PGHS)-2 in acute inflammation. Intrapleural injection of 0.2 ml of 2% lambda-carrageenin induced accumulation of exudate and infiltration of leukocytes into the pleural cavity. When PGHS-1 and -2 proteins in the pleural exudate cells were analyzed by Western blot analysis, PGHS-2 was detectable from 1 hr after carrageenin injection. Its level rose sharply, remained high from 3 to 7 hr after injection, and then fell to near the detection limit. PGHS-1 was also detected, but kept almost the same level throughout the course of the pleurisy. Levels of prostaglandin (PG) E2 and thromboxane (TX) B2 in the exudate increased from hour 3 to hour 7, and then declined. Thus, the changes of the level of PGE2 were closely paralleled those of PGHS-2. The selective PGHS-2 inhibitors NS-398, nimesulide and SC-58125 suppressed the inflammatory reaction and caused a marked decrease in the level of PGE2 but not in those of TXB2 and 6-keto-PGF 1 alpha. These results suggest that the PGHS-2 expressed in the pleural exudate cells may be involved in PGE2 formation at the site of inflammation.

Hypertension induced by a nonpressor dose of angiotensin II in kininogen-deficient rats.

Brown Norway Katholiek rats with very low levels of plasma kininogens excreted a much smaller amount of kinin in the urine than normal rats of the same strain. The systolic blood pressure of 7-week-old kininogen-deficient rats (132 +/- 2 mmHg, n = 7) was not different from that of normal rats. Angiotensin II (Ang II) (20 micrograms/d SC) from 7 weeks of age for 2 weeks with a micro-osmotic pump caused significant increases in blood pressure (181 +/- 5 mm Hg, n = 7, 9 weeks old) in the deficient rats, although the same treatment induced no blood pressure increase in the normal rats. Also during this period, the deficient rats had significantly higher heart rates, tended to excrete less urinary sodium, and showed significantly higher sodium levels in serum, erythrocytes, and cerebrospinal fluid compared with the normal rats. Ang II increased urinary excretion of aldosterone in both deficient and normal rats (P < .05). Spironolactone treatment (50 mg/kg per day) for 7 days in deficient rats restored blood pressure and heart rate to normal levels and significantly reduced sodium levels in erythrocytes and cerebrospinal fluid. Subcutaneous infusion of bovine low-molecular-weight kininogen with an osmotic pump in Ang II-treated deficient rats induced significant reductions in blood pressure, heart rate, and erythrocyte sodium levels. By contrast, subcutaneous infusion of the bradykinin antagonist Hoe 140 in Ang II-treated normal rats induced a hypertensive response in parallel with significant increases in heart rate and erythrocyte sodium level. These results suggest that the lack of kinin generation observed in the kininogen-deficient rats may cause the hypertensive response during the administration of a nonpressor dose of Ang II mainly through sodium retention probably caused by aldosterone release.

Effects of an orally active non‐peptide bradykinin B2 receptor antagonist, FR173657, on plasma exudation in rat carrageenin‐induced pleurisy

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‐quinolinyl)oxymethyl]phenyl]‐N‐methylaminocarbonylmethyl] acrylamide) on the plasma exudation in rat carrageenin‐induced pleurisy were investigated. 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. The inhibitory effect of 30 mg kg−1 FR173657 persisted for more than 4 h. Intrapleural injection of λ‐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. 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.). 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.). These results indicate that FR173657 is an orally active, promising anti‐inflammatory agent for kinin‐dependent inflammation.

Poststatin, a novel inhibitor of bradykinin-degrading enzymes in rat urine

Incubation of bradykinin with rat urine resulted in the successive degradation of bradykinin to bradykinin-(1-8), bradykinin-(1-7) and bradykinin-(1-6). In contrast, in rat plasma, bradykinin was degraded via either bradykinin-(1-8) or bradykinin-(1-7) to bradykinin-(1-5). Phosphoramidon (1 mM) partially inhibited the degradation of bradykinin by rat urine, as well as the conversion of bradykinin-(1-7) to bradykinin-(1-6). D,L-2-Mercaptomethyl-3-guanidinoethylthiopropanoic acid (1 mM) and captopril (1 mM) did not have a significant effect on any of the degradation steps in rat urine. In contrast, all of the degradation steps in urine, namely, from bradykinin to bradykinin-(1-8), from bradykinin-(1-8) to bradykinin-(1-7) and from bradykinin-(1-7) to bradykinin-(1-6), were markedly inhibited by poststatin (1 mM), even though this compound was reported originally to be a novel inhibitor of post-proline cleaving enzyme. Poststatin (1 mM) did not inhibit the degradation of bradykinin in rat plasma. These results indicate that poststatin is an effective inhibitor of kinin-degrading enzyme in rat urine.

Increased migration of neutrophils to granulocyte-colony stimulating factor in rat carrageenin-induced pleurisy: Roles of complement, bradykinin, and inducible cyclooxygenase-2

Administration of human recombinant granulocyte colony-stimulating factor (G-CSF, 100 μg/kg/day, s.c) to rats for 4 days significantly increased circulating neutrophil counts (by 1130%), together with an increase in mononuclear leukocyte counts (by 119%). Infiltrated pleural neutrophil counts in G-CSF-treated rats (G-CSF-r) 5h after the intrapleural injection of zymosanactivated serum were significantly higher (by 155%) than those in control rats (Vehicle-r). In carrageenin-induced pleurisy, counts of infiltrated pleural neutrophils in G-CSF-r 5 and 7h after carrageenin were significantly higher (by 119% and 116%) than those in Vehicle-r. G-CSF treatment increased the volume of pleural exudate and the plasma exudation rate by 122% and 226%, compared to values in Vehicle-r 5h after carrageenin. Cobra venom factor (75 μg/kg, i.v.) significantly reduced pleural neutrophil migration in G-CSF-r (by 53%) and Vehicle-r (by 49%). Bromelain (10 mg/kg, i.v.) and aspirin (100 mg/kg, p.o.) reduced pleural neutrophil migration and reduced exudate volume and plasma exudation. Intrapleural bradykinin-(1–5) and prostaglandin E2 levels were significantly higher in G-CSF-r than in Vehicle-r. The increased neutrophil migration in G-CSF-r may be atributed to enhanced activation of the complement system facilitated by increased plasma exudation due to bradykinin and prostaglandins.

Ebelactone B, an inhibitor of urinary carboxypeptidase Y-like kininase, prevents the development of deoxycorticosterone acetate-salt hypertension in rats

Kininogen-deficient Brown Norway Katholiek rats (BN-Ka) excrete little urinary kinin, compared with normal rats of the same strain (BN Kitasato rats (BN-Ki)). Deoxycorticosterone acetate-salt treatment increased systolic blood pressure in both rats, but much faster in BN-Ka than in BN-Ki. Daily subcutaneous administration of ebelactone B (15 and 5 mg/kg/day), a rat urinary carboxypeptidase Y-like kininase inhibitor, significantly reduced systolic blood pressure in BN-Ki, but not in BN-Ka. This treatment significantly increased urinary Na+ excretion and reduced Na+ concentration in the erythrocytes in BN-Ki, but not in BN-Ka. An angiotensin-converting enzyme inhibitor, lisinopril (5 mg/kg/day s.c.), did not reduce the systolic blood pressure in either BN-Ki or BN-Ka. These results suggested that ebelactone B has promise as a preventive agent for the development of hypertension acting through the inhibition of urinary kinin degradation.

Evidence for a role of kallikrein-kinin system in patients with shock after blunt trauma

Bradykinin (BK) is activated via plasma and/or tissue kallikrein-kinin (K-K) system pathways during hypotension after blunt trauma. The precise role of the K-K system in human subjects has not been defined. We developed a new method for measuring levels of BK in the blood and examined the role of the K-K system in patients with shock after trauma. Eight patients were entered into this study. We measured the levels of a high-molecular-weight kininogen (HMWK), a low-molecular-weight kininogen (LMWK), BK, and (1-5)-BK in the blood of patients in an unstable state (Pre) and a stable state (Post). At Pre, the blood BK level was significantly elevated, the HMWK and LMWK levels were significantly lower, and the (1-5)-BK level was significantly higher than the respective levels at Post. Our data suggest a significant role for the K-K system in the pathogenesis of shock after blunt trauma. This newly developed method for determination of the activation of the plasma K-K system appears to be useful for determining the severity of a trauma.Bradykinin (BK) is activated via plasma and/or tissue kallikrein-kinin (K-K) system pathways during hypotension after blunt trauma. The precise role of the K-K system in human subjects has not been defined. We developed a new method for measuring levels of BK in the blood and examined the role of the K-K system in patients with shock after trauma. Eight patients were entered into this study. We measured the levels of a high-molecular-weight kininogen (HMWK), a low-molecular-weight kininogen (LMWK), BK, and (1-5)-BK in the blood of patients in an unstable state (Pre) and a stable state (Post). At Pre, the blood BK level was significantly elevated, the HMWK and LMWK levels were significantly lower, and the (1-5)-BK level was significantly higher than the respective levels at Post. Our data suggest a significant role for the K-K system in the pathogenesis of shock after blunt trauma. This newly developed method for determination of the activation of the plasma K-K system appears to be useful for determining the severity of a trauma.

Lack of contribution of circulatory kinin elevated by captopril to induce hypotension in normotensive and hypertensive rats.

Captopril (10 mg/kg, i.p.) increased the arterial bradykinin (BK) level (Art-BK) of non-treated Sprague-Dawley rats (SD), determined by an ELISA, from 10.8 +/- 3.2 pg/ml to 32.9 +/- 5.4 pg/ml significantly (p < 0.05, n = 6). Intravenous infusion of BK (100-3000 ng/kg/min) dose-dependently increased heart rate (HR) and decreased mean blood pressure (MBP), the former at lower doses than the latter, and the hypotensive response became significant at 3000 ng/kg/min. Art-BK determined during infusion of the lowest dose of BK (100 ng/kg/min) was 12 times the endogenous Art-BK after captopril administration. In spontaneously hypertensive rats, Wistar Kyoto rats, and deoxycorticosterone acetate-salt treated hypertensive rats, Art-BK (450-1280 pg/ml) determined during intravenous BK-infusion (1000-3000 ng/kg/min), which induced significant hypotension, was 20 to 100 times the endogenous Art-BK (4.5-64 pg/ml) with captopril treatment. These results suggest that the increased Art-BK due to inhibition of kinin degradation by captopril could not account for the hypotension due to this angiotensin converting enzyme inhibitor in normotensive and hypertensive rats.

Evaluation of plasma 11-dehydro-thromboxane B2 as an indicator for thromboxane A2 synthesis in vivo in laboratory animals

Since thromboxane (TX) B2 is not a reliable indicator of TXA2 generation in vivo, because of artifactual TXA2 generation during blood collection, we tested the feasibility of replacing TXB2 with 11-dehydro (dh)-TXB2 as the indicator. Plasma levels of TXB2 and 11-dh-TXB2 were measured after i.v. administration of TXB2 to rabbits, guinea pigs, rats, dogs and a monkey, and after i.v. infusion of collagen in rabbits. In the rabbits and dogs, 2,3-dinor-TXB2 levels were also measured. After intravenous injection of TXB2 (10 micrograms/kg) in rabbits, the ratio of the area under the curve (AUC) of 11-dh-TXB2 to that of TXB2 (1.94) was far higher than the AUC ratio between 2,3-dinor-TXB2 and TXB2 (0.42). When endogenous TXA2 was generated by infusion of collagen (2 mg/kg/5 min), the plasma level of 11-dh-TXB2 was significantly increased, and had a longer half-life than TXB2. In the guinea pigs, rats and monkey, the peak plasma levels of 11-dh-TXB2 were significantly increased after injection of TXB2 (10 micrograms/kg, i.v.), whereas the AUC ratios of 11-dh-TXB2/TXB2 were less than one fourth of that in rabbits. No significant increase in 11-dh-TXB2 was observed after TXB2 injection (10 micrograms/kg) in dogs, but the 2,3-dinor-TXB2 level rose significantly, its AUC ratio to TXB2 being 0.29, comparable with that in rabbits. The order of the 11-dh-TXB2/TXB2 AUC ratios was: rabbits > guinea pigs > monkey > rats >> dogs.(ABSTRACT TRUNCATED AT 250 WORDS)