Inhibition of kinin degradation on the luminal side of renal tubules reduces high blood pressure in deoxycorticosterone acetate salt-treated rats

1. To determine whether the antihypertensive response in deoxycorticosterone acetate (DOCA) salt-treated rats was mediated by kinins on the luminal side of renal tubules or in the circulation, selective urinary kininase inhibitors were administered to normal Brown Norway Kitasato (BN-Ki) rats and kininogen-deficient Brown Norway Katholiek (BN-Ka) rats. 2. Kinins were degraded by neutral endopeptidase (NEP) and carboxypeptidase Y-like kininase (CPY) in urine, but were inactivated mainly by angiotensin-converting enzyme (ACE) in the plasma. 3. Ebelactone B inhibited CPY, while poststatin inhibited CPY and NEP. 4. Daily administration of poststatin (5 mg/kg per day, s.c.) for 3 days reduced blood pressure (BP) in DOCA salt-treated BN-Ki rats, but not in BN-Ka rats. 5. Ebelactone B (5 mg/kg per day, s.c.) also reduced BP in BN-Ki rats, which was accompanied by increased urinary sodium excretion, but had no effect on BP in BN-Ka rats. 6. Lisinopril (5 mg/kg per day, s.c.) had no effect on BP in either rat strain. 7. Arterial kinin levels in BN-Ki rats increased significantly (2.2-4.6 pg/mL) with captopril (10 mg/kg, s.c.). However, arterial kinin levels that induced hypotension following the infusion of bradykinin (1000 ng/kg per min, i.v.) were 110-fold higher than endogenous arterial kinin levels attained following captopril. 8. These results suggest that inhibition of kinin degradation on the luminal side of the renal tubules may effectively attenuate hypertension.

A nonpeptide mimic of bradykinin blunts the development of hypertension in young spontaneously hypertensive rats

We tested whether FR190997, a nonpeptide B(2) agonist, prevented the development of hypertension in young spontaneously hypertensive rats (SHR), which secrete less kallikrein into the urine than do Wistar-Kyoto rats. An intra-arterial (IA) injection of FR190997 (0.3 to 30 nmol/kg) caused dose-dependent hypotension in conscious Sprague-Dawley rats. Although the maximum hypotensive potency of FR190997 equaled that of bradykinin, its action lasted approximately 10 times as long. Hoe140 (100 nmol/kg IA) significantly blocked the hypotensive response induced by FR190997 (10 nmol/kg). Atropine (100 nmol/kg IA) did not affect this response. A selective infusion of FR190997 into the renal artery induced natriuresis and diuresis in anesthetized rabbits. A continuous infusion (2 nmol. 10 mL(-1). h(-1) per rat) of FR190997 into the abdominal aorta of young SHR (6 weeks old, n=6) for 6 days significantly (P<0.05) reduced mean blood pressure to 114+/-6 (day 2) and 110+/-6 (day 5) mm Hg, from 149+/-7 and 162+/-6 mm Hg, respectively, in vehicle-infused rats (n=6). At 8 days after continuous infusion (day 14), mean blood pressure (148+/-5 mm Hg) in FR190997-infused rats remained significantly (P<0. 05) lower than that in vehicle-infused rats (190+/-6 mm Hg), almost the peak value. The mesenteric artery isolated from FR190997-treated rats (day 14) had lower contractile sensitivity to norepinephrine than that from vehicle-treated rats. These results suggested that the continuous infusion of a nonpeptide B(2) agonist may prevent hypertension if performed in the critical phase.

Early increases in renal kallikrein secretion on administration of potassium or ATP-sensitive potassium channel blockers in rats

1 This study aimed to examine whether administration of potassium or ATP-sensitive potassium channel (KATP channel) blockers caused early increases in renal kallikrein (KK) secretion. To clarify this mechanism, the effect on renal KK secretion of a KATP channel blocker was compared with the effect resulting from use of an osmotic diuretic or volume load. Furthermore, the effect on potassium-induced increases in renal KK secretion by an additional treatment using a KATP channel blocker was examined. Lastly, the effect of a KATP channel blocker on renal KK secretion was also examined in superfused slices of kidney cortex. 2 Intravenous infusion of potassium augmented renal KK secretion within 30 min while urine volume increased gradually in both the potassium loading and control groups. 3 Administration of the KATP channel blocker, 4-morpholinecarboximidine-N-1-adamantyl-N'-cyclohexylhydr ochloride (PNU-37883A) or glibenclamide, caused a dose-dependent increase in renal KK secretion. 4 The concentration of KK in urine was higher in the PNU-37883A group as compared to the osmotic-diuretic or volume-load group. 5 PNU-37883A had no additive effect on the potassium-induced increase in renal KK secretion. 6 Renal KK secretion increased in slices of kidney cortex incubated with PNU-37883A within 10 min of superfusion. 7 In conclusion, administration of both potassium and KATP channel blockers induced early increases in renal KK secretion in the absence of the washout phenomenon. Potassium loading may have increased renal KK secretion through the same mechanism as the KATP channel blocker.

K+ loading, but not Na+ loading, and blockade of ATP-sensitive K+ channels augment renal kallikrein secretion

This study aimed to examine whether K+ loading or Na+ loading augments renal kallikrein (KK) secretion. It also investigated the effect of blockade of renal ATP-sensitive K+ channels on renal KK secretion. Rats were administered 50 mmol/kg body weight of KCl. Twelve-hour collected urine was measured for urinary excretion of K+ and Na+ and urinary activity of renal KK. Increases in urinary excretion of K+ and Na+ by K+ loading accompanied an increase in renal KK secretion. In another experiment, rats were infused intravenously with a solution of 75 mM K+ and 75 mM Na+, 150 mM Na+ or 300 mM Na+ for 150 min under anesthesia. Urinary KK activity was measured in urine collected every 30 min. Renal KK secretion began to increase within the 30 min infusion of K+ solution and persisted at more elevated levels during the infusion with K+ solution than with Na+ solutions. Furthermore, rats were given intravenous injection of ATP-sensitive K+ channel blocker, either PNU-37883A (4-morpholinecarboximidine-N-1-adamantyl-N'-cyclohexyl) at a concentration of 10 mg/kg or glibenclamide at 30 mg/kg. Renal KK secretion increased 30 min after administration of both PNU-37883A and glibenclamide. In conclusion, it may be that augmentation of renal KK secretion by K+ loading occurred through an increase in urinary K+ excretion followed by the inhibition of K+ transport from ATP-sensitive K+ channels.

Facilitation of renal kallikrein-kinin system prevents the development of hypertension by inhibition of sodium retention

We have previously reported that the renal kallikrein-kinin system suppressed the development of hypertension, using kininogen deficient Brown Norway Katholiek rats. Kinins were degraded in urine mainly by carboxypeptidase Y-like kininase (CPY). Blockade of renal kinin degradation may prevent the experimental hypertension through the facilitation of the renal kallikrein-kinin system. Daily administration of ebelactone B (EB), which is isolated from Actinomycetes and strongly inhibits CPY, from the first day of deoxycorticosterone acetate (DOCA)-salt treatment for 4 weeks completely blocked hypertension in Sprague-Dawley rats. This treatment reduced sodium levels in erythrocytes and cerebrospinal fluids (CSF) significantly. By contrast, an ACE inhibitor, lisinopril did not prevent hypertension. The development of hypertension in young spontaneously hypertensive rats was also blunted by EB with reductions in sodium levels in erythrocytes and in CSF. The arterial kinin levels in rats undergoing DOCA-salt treatment were 2.2 +/- 0.2 pg/ml, which were increased significantly to 4.6 +/- 0.4 pg/ml with captopril (10 mg/kg, s.c.). The increased kinin levels were less than those to show hypotension. EB did not increase the arterial kinin levels, with significant increase in urinary kinin secretion. These results suggested that facilitation of the renal kallikrein-kinin system by inhibition of kinin degradation on the luminal side of the renal tubules may effectively prevent hypertension.

A secretory mechanism of renal kallikrein by a high potassium ion; a possible involvement of ATP-sensitive potassium channel

A relatively rapid excretion of urinary kallikrein into urine was observed by an intravenous infusion of high potassium in anesthetized rats. Superfusion of sliced cortex isolated from rat kidney with an isotonic solution containing more than 20 mM of KCl significantly stimulated the release of kallikrein. The latter in vitro result supported another mechanism for the release of renal kallikrein from kidney other than biosynthesis of kallikrein by aldosterone released from adrenal cortex after loading of high potassium and the mechanism was elucidated. ATP-sensitive potassium channel blockers, glibenclamide, 4-morpholinecarboximidine-N-1-adamantyl-N'-cyclohexylhydr ochloride (U37883A), and barium chloride, which inhibit an efflux of intracellular potassium to block the channel, showed a significant increase of the kallikrein release from the slice of kidney cortex. Cytochalasin B, which inhibits a polymerization of actin, also showed a stimulation of the release. Enhanced release of kallikrein by a high potassium or ATP-sensitive potassium channel blocker was reduced by the absence of calcium ion and the presence of voltage-dependent calcium channel blocker in the superfused solution. These results indicate the ATP-sensitive potassium channel which couples to voltage-dependent calcium channel and cytoskeletal protein could be involved in a rapid secretory mechanism of renal kallikrein by high potassium.

Interaction between collagens and glycosaminoglycans investigated using a surface plasmon resonance biosensor

The interactions of glycosaminoglycans with collagens and other glycoproteins in extracellular matrix play important roles in cell adhesion and extracellular matrix assembly. In order to clarify the chemical bases for these interactions, glycosaminoglycan solutions were injected onto sensor surfaces on which collagens, fibronectin, laminin, and vitronectin were immobilized. Heparin bound to type V collagen, type IX collagen, fibronectin, laminin, and vitronectin; and chondroitin sulfate E bound to type II, type V, and type VII collagen. Heparin showed a higher affinity for type IX collagen than for type V collagen. On the other hand, chondroitin sulfate E showed the highest affinity for type V collagen. The binding of chondroitin sulfate E to type V collagen showed higher affinity than that of heparin to type V collagen. These data suggest that a novel characteristic sequence included in chondroitin sulfate E is involved in binding to type V collagen.

[Involvement of chymase in angiogenesis in hamster sponge granulomas]

We investigated the angiogenic effect of chymase, an alternative angiotensin II-generating enzyme, on angiogenesis using hamster sponge implant model. Exogenous administration of angiotensin II (Ang II) or angiotensin I (Ang I) directly into the sponges enhanced angiogenesis, as determined from the hemoglobin contents in the sponge granuloma tissues. Chymostatin, an inhibitor of chymase, inhibited angiogenesis induced by Ang I but not by Ang II, suggesting the presence of a chymase-like Ang II-generating activity in the sponge granuloma. TCV-116 (5 mg/kg p.o.), an antagonist of Ang II type 1 receptor, and chymostatin suppressed bFGF-induced angiogenesis, suggesting the significance of the endogenous angiotensin system. Chymase activity in the sponge granuloma increased in parallel with the rise in hemoglobin contents induced by bFGF. We also examined the effects of direct administration of human pro-chymase gene or purified hamster chymase, and demonstrated that in vivo human pro-chymase gene transfection and direct injection of purified chymase enhanced angiogenesis, which was 50% inhibited by TCV-116. Sponge granulomas treated with Ang II was supressed by vascular endothelial growth factor (VEGF) antisense. Our results suggest that chymase enhanced angiogenesis partly through the local production of Ang II, followed by up-regulation of VEGF.

Dilatation and constriction of rat gastric mucosal microvessels through prostaglandin EP2 and EP3 receptors

BACKGROUND

Prostaglandin (PG)E2 has both a vasodilating action and a protective function in the gastric mucosa. There are four subtypes of PGE2-sensitive, or EP, receptors.

AIM

To identify the subtype of EP receptors in the microvessels of the rat gastric mucosa using EP2 and EP3 receptor agonists.

METHODS

The posterior wall of the anaesthetized rat stomach was secured in a chamber and superfused with Tyrode's solution, and the gastric microcirculation of the mucosal base was observed through a window with transillumination. PGE2 and its derivatives (20 microL) were applied topically in the window.

RESULTS

PGE2 (0.001-10 micromol/L), misoprostol (EP2/EP3 receptor agonist; 0.01-100 micromol/L) and butaprost (EP2 receptor agonist; 1-1000 micromol/L) dilated the arterioles dose-dependently, but M&B 28 767 (EP3 receptor agonist; 0.001-10 micromol/L) did not alter their diameters. M&B 28 767 constricted the venules and collecting venules dose-dependently whereas butaprost dilated them. PGE2 and misoprostol had bell-shaped dose-response curves: constriction by low doses of PGE2 and misoprostol (0.001-0.1 micromol/L and 0.01-1 micromol/L) and dilation by high doses of PGE2 and misoprostol (0.1-100 micromol/L and 1-100 micromol/L).

CONCLUSIONS

These results suggest that PGE2 dilated both arterioles and venules in the rat gastric mucosa through the EP2 receptors and constricted the venules through the EP3 receptors.

Enzymatic reconstruction of a hybrid glycosaminoglycan containing 6-sulfated, 4-sulfated, and unsulfated N-acetylgalactosamine

Using the transglycosylation reaction of testicular hyaluronidase, reconstructions of hybrid glycosaminoglycans (GAGs) containing 6-sulfated (GalNAc6S), 4-sulfated (GalNAcS) and unsulfated N-acetylgalactosamine (GalNAc) were investigated. First, chondroitin 4-sulfate (Ch4S) as a donor containing GalNAc4S and the pyridylaminated (PA) chondroitin 6-sulfate (Ch6S) hexasaccharide as an acceptor containing GalNAc6S were subjected to transglycosylation reaction. Second, when the resulting PA-Ch6S(hexa-)-Ch4S(di-)octasaccharide and chondroitin (Ch) were used as an acceptor and as a donor containing GalNAc, respectively, a new decasaccharide having a hybrid structure composed of disaccharide units derived from Ch6S, Ch4S and Ch was reconstructed. Using a systematic combination of each donor and acceptor molecule, it was possible to reconstruct various types of hybrid GAGs.

Effect of prolonged administration of a urinary kinase inhibitor, ebelactone B on the development of deoxycorticosterone acetate-salt hypertension in rats

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.

Reduction of sodium deoxycholic acid-induced scratching behaviour by bradykinin B2 receptor antagonists

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.

Crucial suppressive role of renal kallikrein-kinin system in development of salt-sensitive hypertension

Tissue kallikrein and low molecular weight kininogen are localized in the particular cells of the connecting tubules, indicating that kinin is immediately generated in the lumina of the lower nephrons. The role of the renal kallikreinkinin system was studied using mutant kininogen-deficient Brown NorwayKatholiek (BN-Ka) rats, and compared with that in normal BN-Kitasato rats of the same strain. Mutant BN-Ka rats showed no visible changes, but they were very sensitive to excess sodium ingestion and to the tendency of sodium to accumulate in the body by aldosterone released by angiotensin II, so that sodium was accumulated in erythrocytes and cerebrospinal fluid in BN-Ka rats and hypertension was induced. After four days infusion of 0.3 M NaCl solution to conscious and unrestrained mutant BN-Ka rats, the sensitivity of the vascular smooth muscle to norepinephrine and angiotensin II increased 30-fold and 10-fold, respectively. Bradykinin was degraded by neutral endopeptidase (NEP) and carboxypeptidase Y-like exopeptidase (CPY) in rat and human urine. Daily oral administration of a selective inhibitor of CPY, ebelactone B, or that of NEP, BP1O2, prevented development of deoxycorticosterone acetate-salt hypertension in Sprague-Dawley rats. These results indicate that: 1) the renal kallikrein-kinin system allows excretion of excess sodium in the body, 2) decreased sodium excretion due to reduced excretion of urinary kallikrein in patients with essential hypertension or in genetically hypertensive rats may cause hypertension, and 3) urine kininase inhibitors such as ebelactone B may emerge as a new antihypertensive drug.

Possible background mechanisms of the effectiveness of cyclooxygenase-2 inhibitors in the treatment of rheumatoid arthritis

Cyclooxygenase (COX)-2 was induced in an acute exudative inflammatory model (rat carrageenin-induced pleurisy) in which prostaglandin E2, 6-keto-prostaglandin F1alpha, and thromboxane B2 were generated in the pleural fluid. Selective COX-2 inhibitors, such as NS-398, inhibited the plasma exudation and generation of prostaglandin E2, but not that of thromboxane B2 and 6-keto-prostaglandin F1alpha, in the pleural fluid. In proliferative inflammatory models, COX-2 was induced, and selective COX-2 inhibitors suppressed granuloma formation, particularly, microvessel formation. COX-2 was induced during angiogenesis in a sponge model implanted into skin of rat, and the COX-2 inhibitor suppressed the angiogenesis. As induction of COX-2 was reported in osteoblasts, COX-2 was involved in most characteristic responses of acute exudative inflammation, granuloma formation, bone resorption, and pain in rheumatoid arthritis. The prevention of these COX-2 responses provides a rationale for the effectiveness of COX-2 inhibitors in the treatment of rheumatoid arthritis.

Ion-spray mass spectrometry for identification of the nonreducing terminal sugar of glycosaminoglycan

Various oligosaccharides from hyaluronic acid, which have glucuronic acid or N- acetylglucosamine at the nonreducing terminal, were prepared by digestion with a combination of testicular hyaluronidase and beta-glucuronidase. These oligo saccharides were analyzed by negative-mode ion-spray mass spectrometry (MS) with an atmospheric pressure ion source. Introduction of collisionally activated dissociation tandem mass spectrometry (CAD-MS/MS) produced ions derived from cleavage of the glycosidic bonds, allowing the structure to be analyzed. The CAD-MS/MS spectrum showed an intense and characteristic fragment ion at m/z 193 for oligosaccharides having glucuronic acid at the nonreducing terminal. On the other hand, this ion was not observed in the spectra of oligosaccharides having N- acetylglucosamine at the nonreducing terminal. Therefore, the fragmentation pattern revealed by CAD-MS/MS provides useful information for distinguishing glucuronic acid and N- acetylglucosamine at the nonreducing terminal of oligosaccharides derived from hyaluronic acid and other glycosaminoglycans. This ion-spray CAD-MS/MS technique was also applied successfully to the characterization of glycosaminoglycans reconstructed by glycotechnology.

Effects of a neutral endopeptidase inhibitor, BP102, on the development of deoxycorticosterone acetate-salt hypertension in kininogen-deficient Brown Norway Katholiek rats

The nature of all of the peptides critical to the mechanism(s) of the antihypertensive action of neutral endopeptidase (NEP) inhibitors is still unclear, but bradykinin is thought to be one such peptide. This study was designed to assess the effectiveness of an NEP inhibitor in deoxycorticosterone acetate (DOCA)-salt treated kininogen-deficient Brown Norway Katholiek (BN-Ka) rats. Oral administration of BP102 (10-100 mg/kg), an NEP inhibitor, increased urine volume and urinary sodium excretion in a dose-dependent manner in anesthetized Sprague-Dawley rats. DOCA-salt hypertension was induced in both BN-Ka and Brown Norway Kitasato (BN-Ki) rats after left nephrectomy. The development of DOCA-salt hypertension in normal BN-Ki rats was prevented, and that in BN-Ka rats was also significantly reduced, by an 8-day administration of BP102. When BP102 was administered for 5 weeks, the high blood pressure of DOCA-salt treated BN-Ka rats was markedly lowered, and their heart weights were reduced. These results suggest that kinins play no role in the antihypertensive effect of this inhibitor and that other factors may be involved in this effect.

[The reaction of the nasal mucosa in allergic rhinitis to cold saline stimulus]

To clarify the nature of the reaction pattern of the nasal mucosa in allergic rhinitis, nasal lavage using a cold saline solution of 4 degrees C and a warm saline solution was attempted in 8 patients with nasal allergy to the pollen of the Japanese cedar and cypress in a non-scatter season, and the concentration of protein contents in the nasal washings was determined. The concentrations of total protein, albumin and 26 kD protein were higher in cold saline than in the warm saline lavage. In particular, the concentration of 26 kD protein was 5.3 times higher. However, the concentration was not very high compared with the value obtained by warm saline lavage in the scatter season. These findings indicate that the nasal mucosa of patients with allergic rhinitis is reactive to cold saline stimuli even in the non-scatter season.

Evidence for a role of kallikrein-P6nin 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.

Novel mitochondrial DNA mutation in tRNA(Lys) (8296A-->G) associated with diabetes

Mutation in the mitochondrial gene at position 3243 was recently identified in a large pedigree of diabetes mellitus and deafness. As the mitochondria play an important role in glucose-stimulated insulin secretion in pancreatic beta-cells, we therefore searched for such mutations to detect a candidate gene for diabetes. We screened 10 diabetic subjects with clinical features suggesting mitochondrial DNA mutations. An adenine to guanine point mutation in tRNA(Lys) in at position 8296 (the 8296 mutation) was newly identified. Subsequently, we screened 1216 diabetic subjects, 44 patients with sensorineural deafness subjects and 300 non-diabetic control subjects for this mutation. We identified the mutation in 11 (0.90%) unrelated diabetic subjects, one (2.3%) patient with deafness and no non-diabetic control subject. Seven of these 12 subjects showed maternal inheritance. Deafness was seen in 7 of 12 probands. Four family pedigrees showed maternal inheritance of diabetes over two or three generations. Subjects carrying the 8296 mutation may develop diabetes and the mutation can explain as high as ca. 1% of the causes of diabetes.

Effect of the Kobe earthquake on stress and glycemic control in patients with diabetes mellitus

OBJECTIVE

To examine the effects of the Kobe, Japan, earthquake, a life-threatening event, on stress and glycemic control in diabetic patients.

PATIENTS AND METHODS

Hemoglobin A1c levels before and after the earthquake were evaluated in diabetic patients in Kobe (N = 157; magnitude, 7.2) and in Osaka, Japan, as a control (N = 277; magnitude, 4.2), where little damage to houses and traffic facilities occurred. Glycosylated hemoglobin levels were also compared with those of 2 years before and 1 year after the earthquake. The General Health Questionnaire (GHQ) and a self-administered questionnaire regarding damage to houses and relatives killed or injured were used to assess psychological and mental stresses on earthquake survivors.

RESULTS

Glycemic control was aggravated in diabetic patients after the earthquake in Kobe but not in Osaka. THe GHQ scores were significantly higher in the patients in Kobe than those in Osaka. Increased hemoglobin A1c concentrations and high scores on the GHQ were especially evident in diabetic patients with severe damage to houses and/or with relatives killed or injured.

CONCLUSION

These results suggest an association between chronic, life-threatening stress and the worsening of metabolic control in patients with diabetes mellitus.

Significant roles of inducible cyclooxygenase (COX)-2 in angiogenesis in rat sponge implants

Angiogenesis in rat sponge implants, as determined from the concentration of hemoglobin in the sponge granuloma tissues, was gradually increased over a 14-day experimental period. The inducible cyclooxygenase COX-2 was detected in the sponge granuloma tissues at day 4 by Western blot analysis using specific mouse COX-2 antibody. Angiogenesis in the sponge implants was enhanced by daily topical injections of human recombinant basic fibroblast growth factor (bFGF) or human recombinant epidermal growth factor (EGF) (100 or 1000 ng/sponge/day) for 4 days. These treatments clearly enhanced the expression of COX-2 in the sponge granuloma tissues. In immunohistochemical studies, COX-2-positive staining was mainly observed in the endothelial cells of the neovasculature and in the fibroblasts of the granuloma capsule. Administration of the selective COX-2 inhibitor NS-398 (p.o., 3 mg/kg, 3 times a day) for 14 days significantly inhibited the angiogenesis. The angiogenesis enhanced with bFGF or EGF (day 4) was inhibited by administration of indomethacin or NS-398, both in the above regimen, and fell to the level obtained without growth factor treatment. These results suggest that COX-2 induced in the sponge granuloma tissues may participate in neovascularization through prostaglandin formation.

[Multiple roles of inducible cyclooxygenase-2 and its selective inhibitors]

Cyclooxygenase (COX) is the enzyme that catalyzes the conversion of arachidonic acid to prostaglandin endoperoxides. In addition to constitutive COX-1, inducible COX-2 has been discovered. COX-2 is induced not only in acute exudative rat carrageenin-induced pleurisy, but in granuloma formation/proliferative inflammation for the acceleration of angiogenesis. This means that COX-2 is induced in the healing process of wounds such as in granuloma of gastric ulcer and the proliferative stage of endometrium. COX-2 is also introduced in ovulation and parturition. Osteoblasts induce COX-2 to accelerate bone absorption. Induction of COX-2 in colon carcinoma is a recent, very exciting topic of investigation. We can learn about many unknown roles of COX-2 from its knockout mouse, but the results must be interpreted cautiously. Development of selective COX-2 inhibitors, such as NS-398, opened a new era in which the side effects of gastric and renal lesions by NSAIDs could be ignored. However, prolongation of would healing by the inhibitors and transient expression of COX-2 must be considered in medical intervention with selective COX-2 inhibitors. Nevertheless, acute exudative inflammation, granuloma formation and bone absorption in rheumatoid arthritis are good targets for these inhibitors and application of these inhibitors will be extended to dysmenorrhea, interruption of abortion and increasing survival rate of patients with colon carcinoma.

Role of the renal kallikrein-kinin system in the development of hypertension

Role of renal kallikrein-kinin system has been studied using mutant Brown-Norway Katholiek (BN-Ka) rats, in which both high- and low-molecular weight kininogens were almost absent in plasma and kinin in urine was mainly not detectable. Mutant BN-Ka rats were very sensitive to increased salt intake, resulting in raised systemic blood pressure that is linked to reduced urinary excretion of sodium, when compared with normal BN-Kitasato (BN-Ki) rats. Consequently, sodium accumulated in erythrocytes and cerebrospinal fluid in mutant BN-Ka rats. Subcutaneous infusion of angiotensin II (20 mg/day/rat) also enhanced the concentration of sodium in erythrocytes and in cerebrospinal fluid and increased the systemic pressure by releasing aldosterone. A 4-day infusion of 0.3 M sodium solution (6 ml/kg/h) to the abdominal aorta of conscious and un-restrained mutant BN-Ka rats increased the pressor responses of the arterioles to norepinephrine and angiotensin II (i.a.) by 30- and 10-fold, respectively. Infusion of ebelactone B, (a selective inhibitor of carboxypeptidase Y-like exopeptidase, a kininase in rat urine), to normal BN-Ki rats during induction of hypertension with DOCA and salt, resulted in the reduction of the raised blood pressure, indicating that a site of action of kinins was at the luminal membrane of the renal tubule cells. Our results support the view that the role of renal kallikrein-kinin system is to excrete 'excess sodium' and a reduction in the generation of renal kinins may be a factor in the development of hypertension as a result of the sodium accumulation in the body.

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

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.

Constriction of mouse hepatic venules and sinusoids by endothelins through ETB receptor subtype

OBJECTIVE

This study was conducted to examine the effects of endothelin (ET)-1 and ET-3 on hepatic venules and sinusoids and to identify the subtypes of ET receptors.

METHOD

Hepatic venules and sinusoids of anesthetized mice were observed at the edge of the liver. ET-1, ET-3 and sarafotoxin (S6c, a selective ETB receptor agonist) were applied topically over the microvasculature.

RESULTS

ET-1, ET-3 and S6c (1-100 microM, 30 microliters) induced dose-dependent vasoconstriction of the portal venules, the sinusoids and the central venules. The ETs and S6c were equipotent for these microvessels. BQ-123 (a selective ETA receptor antagonist) inhibited the constrictive effects of ET-3 (not of ET-1) on the portal venules and central venules, whereas it had no inhibitory effect on the sinusoids.

CONCLUSIONS

In mouse hepatic venules and sinusoids, the vasoconstriction induced by ET-1 and ET-3 was mediated mainly through the ETB receptor subtype and partly through an unknown BQ-123-sensitive ET receptor subtype in the portal and central venules, and only through the ETB receptor subtype in the sinusoids.

Induction mechanism of small intestinal lesions caused by intravenous injection of endotoxin in rats

The pathogenesis of intestinal damage caused by bolus intravenous injection of endotoxin (ETX; 3 mg/kg) was investigated. Administration of ETX to rats induced reddish discoloration suggestive of bleeding, increased hemoglobin amounts, and leakage of plasma protein in the intestine. However, light microscopic examination of the intestine demonstrated blood congestion of the microvessels. Plasma accumulation was partially inhibited by combined pretreatment with a histamine H1 antagonist and a serotonin (5-HT) antagonist. Neither a 5-lipoxygenase inhibitor, a soybean trypsin inhibitor, nor atropine was observed to inhibit plasma accumulation. Both the intestinal leakage of plasma and the accumulation of hemoglobin were completely inhibited by indomethacin, a selective thromboxane A synthetase inhibitor (OKY 1581), and a stable PGI2 analogue (beraprost). Intravital microscopic observation of the microvessels of the small intestinal villi demonstrated microthrombus formation within several minutes after the injection of ETX, and pretreatment with OKY 1581 attenuated the formation of microthrombus. Platelet counts decreased significantly 10 min after ETX administration, and the decrease was not inhibited by pretreatment with either OKY 1581 or beraprost. Prothrombin time (PT) and activated partial thromboplastin time (APTT) were not prolonged. These observations thus suggest that microcirculatory disturbances by platelet thrombus, which are mediated by thromboxane A2 at least in part, play an important role in ETX-induced intestinal damage.

Determination of bradykinin-(1-5) in inflammatory exudate by a new ELISA as a reliable indicator of bradykinin generation

We have developed an ELISA for BK-(1-5) (Arg1-Pro2-Pro3-Gly4-Phe5). In rat carrageenin-induced pleurisy, in which a plasma exudation peak was observed 5 h after carrageenin, BK levels in the exudates were negligible (< 60 pg/rat). BK-(1-7) (des-Phe8-Arg9-BK) was detectable (900-400 pg/rat) over the entire course of the inflammation. However, a larger amount of BK-(1-5) was detectable in association with the increase in plasma exudation, showing a peak (8800 +/- 1200 pg/rat) 3 h after carrageenin. Bromelain (10 mg/kg, i.v.) and soy bean trypsin inhibitor (0.3 mg/rat, intra-pleural) significantly reduced BK-(1-5) levels (by 60-93%, 3, 7 and 19 h after carrageenin) and plasma exudation rates (by 61-74%, 3 and 7 h after carrageenin). Dexamethasone (0.3 mg/kg, i.p.) reduced BK-(1-5) levels (by 78%) and decreased plasma exudation (by 70%) 3 h after carrageenin. In nasal allergy patients, antigen challenge of nasal mucosa elevated BK-(1-5) levels and active kallikrein levels in nasal washes. These results verify that BK-(1-5) determined by ELISA is a good indicator for release of kinins in vivo.

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 micrograms/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) 5 h after the intrapleural injection of zymosan-activated 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 7 h 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 5 h after carrageenin. Cobra venom factor (75 micrograms/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 attributed to enhanced activation of the complement system facilitated by increased plasma exudation due to bradykinin and prostaglandins.

Reduction by a kallikrein inhibitor of the increased nasal airway resistance of allergic patients after antigen challenge

Kallikrein activity in nasal lavage fluid, which was measured with a synthetic substrate, Pro-Phe-Arg-methylcoumarilamide, was increased in accordance with the severity of the symptoms of house-dust-mite allergic rhinitis. Antigen challenge was applied to patients with allergic rhinitis by placing a disk containing allergen on the nasal mucosa of the right inferior turbinate. Kallikrein activities and kinin levels in the nasal lavage fluid had increased significantly 15 min after the antigen challenge. These increases were accompanied by a marked increase in nasal airway resistance 15 min after antigen challenge. Pretreatment of the patients with camostat mesilate (60 mg/kg, p.o), a non-peptide serine proteinase inhibitor clinically used in Japan, inhibited the kallikrein activity in the nasal lavage fluid. The increase in nasal airway resistance after antigen challenge was also markedly reduced by oral administration of the inhibitor, indicating involvement of the kallikrein-kinin system in induction of the nasal symptoms.

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.

Role of endogenous substance P in ethanol-induced mucosal damage in the rat stomach

To determine the role of endogenous substance P in ethanol-induced mucosal damage, two experiments were performed. In the first experiment, the stomachs of anesthetized rats were doubly cannulated and gastric damage was induced with 5ml of 30% ethanol in the gastric lumen. The damage was ameliorated by pretreatment with capsaicin (0.16 and 1.6 mM) and spantide (100 mg/kg, i.v.). In the second experiment, the gastric mucosa of these rats was perfused with physiological saline containing pepstatin (10 microliters/ml). Endogenous substance P (SP) in the perfusate was measured by enzyme immunoassay (EIA). The peak SP levels were increased by capsaicin (0.16-1.6 mM) in a concentration-dependent manner. Perfusion with 50% ethanol for 5 min increased the SP levels approximately threefold. Perfusion with 1.6 mM capsaicin, followed by 50% ethanol, reduced the injured area to about one-quarter of the original injured area. The peak SP levels during perfusion with 50% ethanol after pretreatment with 1.6 mM capsaicin did not differ from those observed after vehicle pretreatment (control). The area under the curve for SP release during 50% ethanol perfusion after vehicle perfusion was not reduced by previous perfusion with 1.6 mM capsaicin followed by 50% ethanol, indicating that the prevention of ethanol-induced injury by capsaicin may be due to excess amounts of different neuropeptides released simultaneously.

Failure of the oxytocin-induced increase in secretion of urinary kallikrein in young spontaneously hypertensive rats

Urinary kallikrein excretion during oxytocin (OT) infusion were studied in anesthetized (sodium pentobarbital, 50 mg/kg, i.p.) young (4-weeks-old) spontaneously hypertensive rats (SHR) and Wistar Kyoto rats (WKY). OT-infusion (30 nmol/kg/30 min) to WKY significantly increased urinary excretion of the active kallikrein from the basal levels (25.4 +/- 5.6 10(-2) x AU/15 min, n = 5) to 37.3 +/- 5.0 10(-2) x AU/15 min (P < 0.05, n = 5) and 50.7 +/- 17.1 10(-2) x AU/15 min (P < 0.05, n = 5) 15 and 30 min after the start of OT-infusion, respectively. In SHR, OT-infusion did not increase the urinary excretion of active kallikrein, but did decrease the urine volume and sodium excretion. The concentration of the active kallikrein in the kidney of WKY was not changed by OT-infusion, but that of SHR was slightly increased. The OT-infusion resulted in significantly higher concentrations of the active kallikrein in SHR kidney than in WKY kidney. These results suggest that less excretion of urinary kallikrein in SHR during OT-infusion may be attributable to a lower response in the secretion of kallikrein from the kidney.

Release site of TNF alpha after intravenous and intraperitoneal injection of LPS from Escherichia coli in rats

Lipopolysaccharide (LPS) concentrations in the portal vein after intraperitoneal (i.p.) injection were slightly higher than those in the arteries. The tumor necrosis factor (TNF alpha) levels in arterial serum were higher after i.p. injection than after i.v. injection and rose to a peak at 90 min after some delay. Infusion of LPS into the portal vein increased the TNF alpha levels in the arterial serum. Pretreatment with indomethacin further increased the arterial levels of TNF alpha after portal infusion, but did not after them after i.p. injection, because of the reduction by indomethacin of LPS absorption after i.p. Injection of LPS. TNF alpha was also generated in the peritoneal cavity after i.p. injection of LPS. The TNF alpha concentrations in the arterial serum and in the peritoneal cavity were accelerated by mast cell degradation. In conclusion, TNF alpha was generated mainly in the liver, but also in the peritoneal cavity, after i.p. injection of LPS, and was negatively regulated by prostaglandins.

Pivotal role of renal kallikrein-kinin system in the development of hypertension and approaches to new drugs based on this relationship

Renal kallikrein is one of the tissue kallikreins, and the distal nephron is fully equipped as an element of the kallikrein-kinin system. Although a low excretion of urinary kallikrein has been reported in essential hypertension, the results from studies on patients with hypertension are not consistent. Congenitally hypertensive animals also excrete lowered levels of urinary kallikrein, but the effects of this are yet unknown. Extensive genetic and environmental studies on large Utah pedigrees suggest that the causes of hypertension are closely related to the combination of low kallikrein excretion and the potassium intake. Mutant kininogen-deficient Brown Norway-Katholiek rats, which cannot generate kinin in the urine, are very sensitive to salt loading and to sodium retention by aldosterone released by a non-pressor dose of angiotensin II, which results in hypertension. The major function of renal kallikrein-kinin system is to excrete sodium and water when excess sodium is present in the body. Failure of this function causes accumulation of sodium in the cerebrospinal fluid and erythrocytes, and probably in the vascular smooth muscle, which become sensitive to vasoconstrictors. We hypothesize that impaired function of the renal kallikrein-kinin system may play a pivotal role in the early development of hypertension. Inhibitors of kinin degradation in renal tubules and agents, which accelerate the secretion of urinary kallikrein from the connecting tubules and increase the generation of urinary kinin, may be novel drugs against hypertension.

Role of tachykinins in enhancement of bradykinin-induced bronchoconstriction by captopril

In anesthetized, mechanically ventilated guinea pigs, infusion of captopril (1 mg/kg/h), an angiotensin converting enzyme inhibitor, significantly enhanced bronchoconstriction induced by intravenous injection of bradykinin (BK; 0.1-30 nmol/kg). Pretreatment of guinea pigs with capsaicin (100 mu g/kg) slightly suppressed the bronchoconstriction by BK alone and almost all of the enhancement of BK-induced bronchoconstriction by captopril was suppressed. Intravenous injection of substance P (SP; 0.1-100 nmol/kg), neurokinin A (NKA; 0.1-30 nmol/kg) and neurokinin B (NKB; 0.1-30 nmol/kg) also induced dose-dependent bronchoconstriction but captopril treatment enhanced only the bronchoconstriction induced by SP. BK degradation in bronchoalveolar lavage fluid (BALF) in vitro was significantly suppressed by captopril (p < 0.05). Captopril infusion to guinea pigs significantly increased the levels of BK, SP, and NKA in BALF after BK injection (p < 0.05). FK224, an NK1 and NK2 receptor antagonist and SR 48968, an NK2 receptor antagonist, significantly suppressed the bronchoconstriction induced by BK alone (p < 0.01 and p < 0.05, respectively) as well as the enhancement by captopril (p < 0.01). It can be concluded that the enhancement of BK-induced bronchoconstriction by captopril was attributable to inhibition of the degradation of BK itself and thereby enhanced release of NKA and partly of SP from sensory nerves by BK.

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.

Inhibitory effects of a phosphate diester of alpha-tocopherol and ascorbic acid (EPC-K1) on myocardial infarction in rats

The inhibitory effect of a phosphate diester of alpha-tocopherol and ascorbic acid (EPC-K1) was examined in myocardial infarction induced in rats, in comparison with a selective 5-lipoxygenase inhibitor, AA-861. EPC-K1 significantly reduced the infarct size at 24 and 48 h after ligation, whereas AA-861 reduced it only at 48 h after ligation. In in-vitro experiments, EPC-K1 inhibited not only superoxide anion generation (IC50 = 4.2 x 10(-5) M), but also acid phosphatase activity (IC50 = 2.4 x 10(-5) M) in rat polymorphonuclear leukocytes in a concentration-dependent manner, while AA-861 showed marginal effects on both actions. These results indicated that EPC-K1 induced cardioprotective effects by affecting neutrophil functions by inhibition of generation of superoxide-anion generation and acid-phosphatase activity. The mechanism of the reduction of the infarct size by EPC-K1 differed from that of AA-861, which latter inhibited 5-lipoxygenase and the formation of leukotriene B4.

Induction of cyclooxygenase type-2 (COX-2) in rat endometrium at the peak of serum estradiol during the estrus cycle

We investigated the induction of cyclooxygenase (COX) in rat endometrium during the estrus cycle. The estrus cycle was divided into five stages (proestrus, estrus, diestrus-1, diestrus-2, diestrus-3) by cytological observation of vaginal smears. COX-1 was detected in the endometrium during all five stages of the estrus cycle. In contrast, COX-2 in the endometrium was detectable only in three stages (diestrus-3, proestrus, estrus) and showed a peak at diestrus-3, coinciding with the peak in serum estradiol level, suggesting the estradiol-dependent induction of COX-2.

Increase in vascular sensitivity to angiotensin II and norepinephrine after four-day infusion of 0.3 M sodium chloride in conscious kininogen-deficient brown Norway Katholiek rats

Kininogen-deficient Brown Norway Katholiek (deficient BN-Ka) rats excreted a small amount of kinin in their urine, compared with normal BN Kitasato (normal BN-Ki) rats from the same strain. Intraarterial (i.a.) infusion (6 ml/kg/hr) of conscious deficient BN-Ka rats with 0.15 M NaCl did not increase mean arterial blood pressure (MBP) [from 103 +/- 2 (pre) to 93 +/- 6 mmHg (day 4)] and did not cause sodium accumulation in the serum, cerebrospinal fluid or erythrocytes, but 0.3 M NaCl infusion significantly increased MBP from 104 +/- 3 (pre) to 130 +/- 5 mmHg (day 4) with increased sodium levels in the serum, cerebrospinal fluid and erythrocytes. Infusion of 0.3 M NaCl in normal BN-Ki rats neither increased MBP nor accumulated sodium. The dose-response curve of the increase in MBP for angiotensin II injection (i.a., bolus, 1-1000 pmol/kg) in 0.3 M NaCl-infused deficient BN-Ka rats shifted to the left by a factor of 10 compared with that in 0.15 M NaCl-infused deficient BN-Ka rats, and that for norepinephrine injection shifted to the left by a factor of 30. Normal BN-Ki rats did not show any enhancement in MBP elevation with 0.3 M NaCl. These results suggest that the sodium accumulation attributable to a lack of kinin generation may be related to increased vascular reactivity to angiotensin II and norepinephrine.

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.

Approaches to the development of novel antihypertensive drugs: crucial role of the renal kallikrein-kinin system

The renal kallikrein-kinin system has been shown to be important in the development of hypertension, but its precise role remains to be determined. The recent use of mutant rats that are deficient in plasma kininogens and hence incapable of generating kinin in the renal tubules has facilitated elucidation of the involvement of kinin in hypertension. In this article, Masataka Majima and Makoto Katori provide evidence that the renal kallikrein-kinin system plays a crucial role in the development of hypertension and discuss a novel rationale for developing effective new antihypertensive drugs.

A patient with diabetes mellitus, cardiomyopathy, and a mitochondrial gene mutation: confirmation of a gene mutation in cardiac muscle

A 44-year-old woman with diabetes mellitus, cardiomyopathy, and a mitochondrial gene mutation, was reported. She was diagnosed as having diabetes at 33 years of age and was treated with insulin. However, she stopped treatment 6 months later and had no medical care until she developed diabetic ketoacidosis at 41 years of age. She had diabetic foot, diabetic retinopathy, and nephropathy with low insulin secretory capacity, leading to insulin treatment. A point mutation of the mitochondrial tRNA(Leu(UUR)) gene was identified in peripheral leukocytes at 43 years of age, and sensorineural hearing impairment was detected at the same time. Her mother also suffered from diabetes mellitus with deafness and her son, who was not diabetic at age 19, had the same mitochondrial DNA (mtDNA) mutation. At 44 years of age, she developed congestive heart failure due to cardiomyopathy, and the same mtDNA mutation was identified in the cardiac muscle. Thus, it is very likely that in this patient, diabetes and cardiomyopathy was caused by the same abnormality, the point mutation of mitochondrial tRNA(Leu(UUR)) gene.

Oxytocin-induced natriuresis mediated by the renal kallikrein-kinin system in anesthetized male rats

Intravenous infusion of oxytocin (OT) (10-100 nmol/kg/30 min) to 8-week-old anesthetized male rats resulted in a dose-dependent increase in urine volume, which showed a peak value 30-45 min after the start of OT-infusion. Urinary excretions of sodium, chloride and potassium were also increased by OT, showing peak values at 30-45 min, without any increase in the creatinine level. The natriuresis by OT was accompanied by increased excretion of urinary active kallikrein, which showed a peak value 15 min after the start of OT-infusion. The urinary kinin level was also increased. Intravenous infusion of a kallikrein inhibitor, aprotinin (15 mg/kg/90 min), when started 30 min before the OT-infusion, significantly inhibited the OT-induced increase in urine volume and urinary excretion of sodium, chloride and potassium. Intravenous infusion of a bradykinin B2 antagonist, Hoe 140 (D-Arg[Hyp3,Thi5,D-Tic7,Oic8]BK, 4.5 mg/kg/90 min), when started 30 min before the OT-infusion, significantly inhibited the OT-induced increases in urine volume and urinary excretion of sodium and chloride, but not that of potassium. These results indicate that the OT-infusion induces natriuresis in male rats, and more than half of the natriuresis is mediated by a concomitant increase in excretion of urinary active kallikrein and the kinin generated.

Enzymic reconstruction of glycosaminoglycan oligosaccharide chains using the transglycosylation reaction of bovine testicular hyaluronidase

The reconstruction of glycosaminoglycan chains using the transglycosylation reaction of testicular hyaluronidase was investigated. First, the optimal conditions for the transglycosylation reaction catalyzed by the enzyme were determined by incubation with the enzyme, using hyaluronic acid (M(r) = 800,000) as a donor and pyridylaminated hyaluronic acid hexasaccharide having glucuronic acid at the nonreducing terminal as an acceptor. The carbohydrate chains as reaction products were determined by high performance liquid chromatography and mass spectrometry. The optimal pH for hydrolysis by the enzyme was found to be about 5.0, whereas that for the transglycosylation reaction was about 7.0. Sodium chloride in the reaction medium inhibited the transglycosylation reaction. Under the optimal conditions, the carbohydrate chains were sequentially transferred along with disaccharide units to the nonreducing terminal of the acceptor and elongated up to docosasaccharide from the acceptor, pyridylaminated hexasaccharide. Using a combination of hyaluronic acid, chondroitin, and chondroitin 4- and 6-sulfate as an acceptor and a donor, it was possible to reconstruct hybrid chains, which were natural or unnatural types of glycosaminoglycan chains. Therefore, it is highly likely that application of the transglycosylation reaction using testicular hyaluronidase would facilitate artificial reconstruction of glycosaminoglycans having some physiological functions.

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.

Characterization of hydrolysis and transglycosylation by testicular hyaluronidase using ion-spray mass spectrometry

Various oligosaccharides from hyaluronic acid, which were fluorescence-labeled and blocked by pyridylamination at the reducing terminal, were incubated as substrates or acceptors with bovine testicular hyaluronidase. Fluorescence-labeled reaction products in the reaction mixture were monitored selectively and directly by ion-spray mass spectrometry without chemical derivatization. As a result, several features of the relationship between oligosaccharides, substrates, and testicular hyaluronidase were clarified. When hexasaccharides or larger oligosaccharides having D-glucuronic acid at the nonreducing terminal were used as substrates, they were hydrolyzed sequentially to disaccharides from the nonreducing terminal, and these disaccharides were then transferred to other hexasaccharides. On the other hand, when heptasaccharides or larger oligosaccharides having N-acetyl-D-glucosamine at the nonreducing terminal were used as substrates, trisaccharides were released from the nonreducing terminal, and then also transferred to other hexasaccharides, thus forming nonasaccharides. Thus, the relationship between hydrolysis and transglycosylation reactions with testicular hyaluronidase was characterized using ion-spray mass spectrometry.

Diuretic and natriuretic effect of ebelactone B in anesthetized rats by inhibition of a urinary carboxypeptidase Y-like kininase

Ebelactone B (EB) (10(-7)-10(-5) M) inhibited dose-dependently carboxypeptidase (CP) Y-like exopeptidase, one of the major kininases separated from rat urine, whereas it inhibited neither CPA, CPB or neutral endopeptidase (NEP). Degradation of bradykinin (BK) to BK-(1-8) in rat urine was completely inhibited by EB (10(-5) M) with the increased generation of BK-(1-7). Intraduodenal administration of EB (3 mg/kg) to anesthetized rats caused marked diuresis (by 110%) and natriuresis (130%), in parallel with the increase in urinary kinin levels (110%). Intravenous infusion of a BK antagonist, Hoe140 (3 mg/kg/hr), strongly blocked both EB-induced diuresis and natriuresis. EB may be a novel type of diuretic and natriuretic agent that acts by increasing urinary kinin levels.