Kinin Concentrations Research Articles

Absence of effect of chronic angiotensin II type 1 receptor blockade on endogenous kinin concentrations in the carrageenan-induced paw edema model in the rat

The effects of chronic treatment with losartan, an AT 1 receptor antagonist, on the tissue content of bradykinin (BK) and des-Arg 9-BK and on their pharmacological effects were examined in the carrageenan-induced paw edema model (0.5% solution, 50 μl/paw) in the rat. These effects were compared with those of angiotensin-converting enzyme inhibitors (ACEi). For this purpose, rats were chronically treated with losartan (3, 10 and 30 mg/kg/day) and enalapril or quinapril (1 mg/kg/day). Endogenous BK and des-Arg 9-BK tissue contents at the site of local inflammation were measured by highly sensitive and specific enzyme immunoassays. Losartan 3 mg/kg/day for 7, 14 and 28 days had no significant effect on carrageenan-induced paw edema, but both losartan 10 and 30 mg/kg/day for 14 days significantly increased the hindpaw volume by 50% at 3 h and by 59% at 5 h. These effects, similar to those measured for ACEi, were inhibited by icatibant, a B 2 kinin receptor antagonist (32.5 nmol/paw), that reduced carrageenan-induced paw edema to the level seen in vehicle-treated rats. In the same model, and contrary to ACEi, losartan 3, 10 and 30 mg/kg/day for 14 days had no significant effect on endogenous BK and des-Arg 9-BK levels in the local inflammatory site or on circulating and tissue ACE activities. These results show, at least in that model, that the potentiating effects of losartan on carrageenan-induced paw edema are independent of the concentrations of endogenous kinins.

Involvement of ovarian kinin-kallikrein system in the pathophysiology of ovarian hyperstimulation syndrome: studies in a rat model.

The purpose of the present study was to investigate a possible participation of the kinin-kallikrein system (KKS) in the pathophysiology of ovarian hyperstimulation syndrome (OHSS). Symptoms of hyperstimulation were produced in immature female rats using equine chorionic gonadotrophin followed by human chorionic gonadotrophin (HCG). At 48 h after the HCG injection, rats were injected s.c. with 100 microg/kg of HOE140, bradykinin-2 receptor antagonist. Capillary permeability was evaluated using peritoneal Evans blue dye (EB) concentrations 30 min after the i.v. injections. The EB concentrations in the hyperstimulated rats were significantly reduced 4 and 6 h after the HOE140 injection, compared with those injected with the vehicle as a control (4.58+/-0.80 versus 8.22+/-0.87 and 4.32+/-0.74 versus 8.35+/-1.03 microg respectively; P < 0.03), indicating the involvement of kinin in the pathophysiology of OHSS in this model. The administration of 10 IU aprotinin significantly reduced the peritoneal EB concentration when compared with the control (4.13+/-0.53 versus 7.95+/-1.06 microg; P < 0.01), implicating a possible role of kallikrein. Furthermore, pretreatment with RU486 (5 or 10 mg/kg) resulted in a significant reduction of ovarian kinin concentrations 48 h after the HCG injection, compared with the control (1.22+/-0.07 or 1.43+/-0.07 versus 1.94+/-0.10 pg/mg; P < 0.005 and P < 0.05 respectively). Similar results were obtained in the peritoneal EB concentrations. In addition, a significant correlation between the ovarian kinin and peritoneal EB concentrations was observed (P < 0.001, r = 0.539). Thus it was suggested that ovarian KKS plays an intermediary role in the progesterone-induced augmentation of capillary permeability in this experimental model, indicating the involvement of KKS in the pathophysiology of OHSS.

Plasma bradykinin in angio-oedema

Bradykinin is believed to be the main mediator of symptoms in hereditary (HA) and acquired (AA) angio-oedema due to C1 esterase inhibitor deficiency, as well as in angio-oedema that complicates treatment with inhibitors of angiotensin-converting enzyme (ACE). Difficulties in the measurement of kinin concentrations, however, have so far precluded the demonstration of an incontrovertible change in plasma bradykinin concentrations in these disorders. By developing a reliable assay we have been able to follow bradykinin concentrations during attacks and during remission in HA and in AA, and also in a patient treated with an ACE-inhibitor. Liquid-phase extraction, high-performance liquid chromatography, and RIA were used for specific measurement of plasma bradykinin concentrations in 22 patients with HA and in 22 healthy volunteers of similar age and sex distribution. Four patients with AA and one hypertensive patient treated with the ACE inhibitor captopril were also studied. Among the healthy volunteers plasma bradykinin concentration was inversely proportional to age. The geometric mean plasma bradykinin concentration in the healthy volunteers was 2.2 fmol/mL (SD 2.2), compared with 3.9 fmol/mL (3.7) among patients with HA during remission (p=0.095). Bradykinin was also high in the patients with AA (10.4 fmol/mL [1.6]). During acute attacks of oedema, in both HA and AA, plasma bradykinin rose to two to 12 times the upper limit of normal. Infusion of C1-esterase inhibitor (the deficient factor in both HA and AA) immediately lowered bradykinin concentrations. In the patient receiving the ACE-inhibitor captopril, bradykinin concentration was very high at 47 fmol/mL during an acute attack of angio-oedema, but normal at 3.2 fmol/mL in remission after withdrawal of the drug. A sensitive method for measurement of plasma bradykinin provided the means to show that concentrations of this peptide decrease with age in healthy people. Although the differences between patients in remission and healthy controls did not reach statistical significance, there were substantial rises in bradykinin during acute attacks of hereditary, acquired, or captopril-induced angio-oedema.

The involvement of plasma kinins in the cardiovascular effects of Leiurus quinquestriatus scorpion venom in anaesthetised rabbits

The present study was undertaken to investigate the involvement of kinins in the cardiovascular and respiratory effects of LQQ venom. Blood pressure, heart rate, electrocardiogram (ECG) and respiration were studied in anaesthetised rabbits, in the presence and absence of aprotinin and icatibant, a B 2 bradykinin antagonist. Plasma bradykinin concentrations were also measured following venom injection. LQQ venom caused a triphasic effect on blood pressure comprising an immediate fall, a pronounced rise and a progressive decline until death. Bradycardia, myocardial damage, arrhythmias, respiratory distress and pulmonary oedema were also exhibited. Pretreatment with aprotinin attenuated the venom-induced hypotension, bradycardia, ECG and respiratory changes and prolonged survival. Pretreatment of atropinized animals with icatibant gave similar protection. In animals treated with LQQ venom, plasma bradykinin was significantly higher than controls, although there was considerable inter-animal variation in plasma kinin concentrations and the elevation was seen relatively late after venom administration. The data provides some support for the hypothesis that kinins are involved in the cardiovascular and lethal effects of LQQ venom in rabbits.

Bradykinin B 2 -Receptor Activation Augments Norepinephrine Exocytosis From Cardiac Sympathetic Nerve Endings

We determined whether local bradykinin production modulates cardiac adrenergic activity. Depolarization of guinea pig heart sympathetic nerve endings (synaptosomes) with 1 to 100 mmol/L K+ caused the release of endogenous norepinephrine (10% to 50% above basal level). This release was exocytotic, because it depended on extracellular Ca2+, was inhibited by the N-type Ca(2+)-channel blocker omega-conotoxin and the protein kinase C inhibitor Ro31-8220, and was potentiated by the neuronal uptake-1 inhibitor desipramine. Typical of adrenergic terminals, norepinephrine exocytosis was enhanced by activation of prejunctional angiotensin AT1-receptors and attenuated by adrenergic alpha 2-receptors, adenosine A1-receptors, and histamine H3-receptors. Exogenous bradykinin enhanced norepinephrine exocytosis by 7% to 35% (EC50, 17 nmol/L), without inhibiting uptake 1. B2-receptor, but not B1-receptor, blockade antagonized this effect. The kininase II/angiotensin-converting enzyme inhibitor enalaprilat and the addition of kininogen or kallikrein enhanced norepinephrine exocytosis by approximately equal to 6% to 40% (EC50, 20 nmol/L) and approximately equal to 25% to 60%, respectively. This potentiation was prevented by serine protease inhibitors and was antagonized by B2-receptor blockade. Therefore, norepinephrine exocytosis is augmented when bradykinin synthesis is increased or when its breakdown is inhibited. This is the first report of a local kallikrein-kinin system in adrenergic nerve endings capable of generating enough bradykinin to activate B2-receptors in an autocrine/paracrine fashion and thus enhance norepinephrine exocytosis. This amplification process may operate in disease states, such as myocardial ischemia, associated with severalfold increases in local kinin concentrations.

Angiotensin-Converting Enzyme Inhibitors Promote Nitric Oxide Production in Coronary Microvessels from Failing Explanted Human Hearts

We have previously shown that nitric oxide (NO) release by the coronary circulation in the failing and nonfailing human heart is, in part, regulated by local kinin production in coronary microvessels. Angiotensin-converting enzyme (ACE) also known as kininase II, inactivates kinins. ACE inhibitors prevent kinin breakdown by ACE, thereby increasing the concentration of bradykinin (BK) and related kinins. The goal of this study was to determine if kinins contribute to the therapeutic action of ACE inhibitors. Six hearts from end-stage heart failure patients were harvested at the time of orthotopic cardiac transplantation. Microvessels were prepared as previously described, and nitrite production, a metabolic product of NO in vitro, was determined by the Griess reaction. Microvessels were incubated in the presence of kininogen and bradykinin, and with the ACE inhibitors ramiprilat, enalaprilat, or captopril. All caused dose-dependent increases in nitrite. For instance, ramiprilat increased nitrite from 76 ± 5.6 to 155 ± 15 pmol/min per mg wet weight. Nitrite production in response to ACE inhibition was blocked by N-nitro-l-arginine methyl ester (l-NAME), a NO synthase inhibitor, and icatibant (HOE 140), a B2-kinin receptor-specific antagonist. Furthermore, NO production was prevented by 3 different serine protease inhibitors, which block kallikrein, the enzyme responsible for conversion of kininogen to kinins. Our results indicate that ACE/kininase inhibitors increase NO production by the coronary microvasculature in the failing human heart, through increased available active kinins. The therapeutic action of ACE inhibition in the failing human heart may result in part from increased NO production by coronary microvessels.

Generation of kinins in synovial fluid from patients with arthropathy

An enzyme-linked immunosorbent assay method is described for the measurement of kinin formation in synovial fluid from patients with rheumatoid and osteoarthritis (RA and OA). Basal kinin concentrations were less than 6 ng/ml in synovial fluid collected in the presence of inhibitors of kinin forming (kininogenase) and kinin metabolising (kininase) enzymes. During incubation of synovial fluid in the presence of kininase inhibitors alone, kinins were produced rapidly over the first 10 min, but production ceased completely within 30 min due to inhibition of the endogenous kininogenases; the rate of kinin generation during the early rapid phase correlated well with the plateau kinin concentration. Plateau kinin levels in synovial fluid from 15 patients with OA and RA ranged from 98 to 427 ng/ml, with a median value of 148 ng/ml. This study demonstrates clearly that synovial fluid from arthritis patients has the capacity to produce kinins. Although the number of patients was small, the amount of kinin generated in vitro varied over a wide range and a relationship between intra-articular kinin formation and clinical features may become apparent in a larger group of patients. The technique could also be used to investigate other biological systems in which a role has been proposed for kinins.

Pharmacokinetic Studies of Human Urinary Kininogenase in Healthy Volunteers and Animals

Plasma concentrations of human urinary kininogenase (HUK) were determined in healthy volunteers during and after intravenous (iv) infusion by enzyme immunoassay (EIA). Plasma kinin concentrations were also determined by radioimmunoassay (RIA), and related to HUK concentrations. When HUK was infused [at 0.04, 0.075, 0.15, and 0.3 p-nitroaniline unit (PNAU)/body] over 30min, plasma HUK concentration rapidly increased and reached a maximum at the end of dosing. Then, the concentration of HUK in plasma decreased biexponentially, and the elimination half-life of the terminal phase was found to be ∼170min. The area under the curve of concentration versus time from 0 to 180min (AUC0–180min) and the maximum concentration (Cmax) increased in proportion to the dose, whereas the pharmacokinetic parameters [mean residense time (MRTinf)=200–270min, plasma clearance (CLp)=2.5–3.3mL/min/kg, volume of distribution at steady state (Vdss)=470–730mL/kg] did not vary significantly within the dose range of the present study. On the other hand, when HUK was infused (at 0.15 PNAU/body), plasma kinin concentrations reached ∼2ng of bradykinin eq/mL 15min after the onset of administration. This concentration was maintained during the dosing period, after which kinin was rapidly eliminated, and its concentration returned to baseline at 10min after dose withdrawal. Plasma kinin concentrations at 15 to 30min after the onset of dosing (at 0.075, 0.15, and 0.3 PNAU/body) increased in proportion to the dose. The pharmacokinetic parameters of HUK (MRTinf, CLp, Vdss) were compared with those of rats, rabbits, and dogs (log–log plots of body weight versus MRTinf, CLp, and Vdss). The Vdss value showed a good correlation (r=0.996 for n=4) with the body weight of respective animal species, the correlation with CLp was weak (r=0.911), and MRTinf did not exhibit any correlation.

Bradykinin stimulates alveolar macrophages to release neutrophil, monocyte, and eosinophil chemotactic activity.

Bronchial asthma is accompanied with inflammatory cell infiltration in the airway. Because kinin activity was detected in bronchoalveolar lavage fluid (BALF) from asthmatic patients, and because the concentrations of kallikrein and kinins in BALF increased after allergen challenge, we evaluated the potential that bradykinin (BK) might stimulate alveolar macrophages (AM) to release neutrophil, monocyte, and eosinophil chemotactic activity (NCA, MCA, and ECA). To test this hypothesis, bovine AM were isolated by bronchoalveolar lavage and cultured. The supernatant fluids of AM were tested for chemotactic activity by a blind well chamber technique. AM released NCA, MCA, and ECA in response to BK in a dose-and time-dependent manner (p < 0.01). The released activities were chemotactic by checkerboard analysis. Partial characterization and molecular sieve column chromatography revealed that these released activities were heterogeneous, suggesting predominant low-m.w. lipid soluble activity and weak high-m.w. peptide activity. Lipoxygenase inhibitors blocked the release of chemotactic activities (p < 0.01). The chemotactic activities were partly inhibited by leukotriene B4 (LTB4) and platelet-activating factor (PAF) receptor antagonists (p < 0.05, respectively). Immunoreactive LTB4 significantly increased in supernatant fluids in response to BK (p < 0.05), but PAF was detected only two out of six samples stimulated by BK. The receptor responsible for the release of LTB4 involved both BKB1 and BKB2 receptors. These data suggest that BK may stimulate AM and play a role in bronchial inflammation by recruiting inflammatory cells into the airway.

T-kinin is resistant to hydrolysis by angiotensin I-converting enzyme

Several enzymes of are capable of cleaving kinins at either the N- or C-terminal end. In this work, we investigated the hydrolysis of T-kinin (TK) and bradykinin (BK) by carboxypeptidase B (CpB) and angiotensin I-converting enzyme (ACE). The kinins were incubated with the enzymes in Tyrode solution kept at 37°C for 25 min. The kinin residual activity in the incubation medium was bioassayed on the isolated guinea pig ileum. BK (5 μg/ml) and TK (5 μ/ml) were rapidly and similarly degraded by CpB (0.088 mU/ml) since half of both kinins was inactivated within 5 min of incubation. At 25 min of incubation with CpB the TK and BK-like activities were 20.8 ± 3.9 (1.04 ± 0.20 μg/ml) and 31.8 ± 5.0% (1.59 ± 0.25 μg/ml) of the initial kinin concentrations, respectively. BK was also rapidly inactivated by ACE (5 mU/ml) while TK activity was unaffected. At 25 min the BK and TK residual activities corresponded to 39.4 ± 2.5 (1.97 ± 0.13 μg/ml) and 93.8 ± 9.2% (4.69 ± 0.46 μg/ml) of the initial kinin concentrations, respectively. It was concluded that TK, a kinin elongated at the N-terminal position, is resistant to ACE degradation.

Plasma kinins increase after angiotensin-converting enzyme inhibition in human subjects.

1. In patients treated with angiotensin-converting enzyme inhibitors, kinin-related effects have been postulated repeatedly, but information on changes in plasma kinin levels in these patients is sparse. Difficulties in the measurement of plasma kinins account for this, at least in part. 2. The main purpose of the present study was to investigate, in normal human subjects, the effect of the angiotensin-converting enzyme inhibitor quinapril on plasma kinins. 3. High-affinity antisera (Kd < 10(-11) mol/l) of C-terminal specificity were raised in rabbits for radioimmunoassay of immunoreactive kinins activating the bradykinin B2-receptor, and three different liquid- and solid-phase extraction methods for plasma kinins were evaluated. Ethanol and subsequent petroleum ether extraction of 5-40 fmol of bradykinin added to plasma yielded recoveries of 39 +/- 16% (mean +/- SD); normal kinin levels in human plasma were 18.6 +/- 3.3 pmol/l (mean +/- SEM). Solid-phase extraction on urea-equilibrated phenylsilylsilica produced recoveries of 89 +/- 5% and normal values of 36.4 +/- 18 pmol/l. Finally, with an assay based on ethanol extraction alone, recoveries of 100 +/- 16% and normal values of 16.8 +/- 5.8 pmol/l were obtained, with a detection limit of 1.5 fmol/ml of plasma. Blanks were below the detection limit. Serial dilution of plasma extracts (n = 4) provided linear kinin concentrations (r = 0.99). For two different plasma pools, coefficients of variation for within-assay precision were 16.7% and 21.7%, respectively. Between-assay coefficients of variation were 12.8% and 17.4%.(ABSTRACT TRUNCATED AT 250 WORDS)

Tissue kallikrein activity and kinin release in human endothelial cells.

The kininogenase, tissue kallikrein (EC 3.4.21.8), has been identified in different blood vessels. The enzyme was mainly found in vascular smooth muscle cells. It is not known whether it is present and functionally active in vascular endothelial cells. The following study investigates the presence of tissue kallikrein in endothelial cells from human umbilical veins and pulmonary arteries. Tissue kallikrein was demonstrated in three ways: 1) by immunostaining in endothelial cells; 2) by measurement of tissue kallikrein activity using a colorimetric assay; 3) by the measurement of kinin release in intact and homogenised endothelial cells with a radioimmunoassay. Immunostaining demonstrated the presence of tissue kallikrein in endothelial cells from human umbilical veins and endothelial cells from human pulmonary arteries. Tissue kallikrein-like activity, measured by the degradation of D-Val-cyclohexyl-Ala-Arg-4-nitraniline, was 3.57 +/- 0.5 mU/10(6) endothelial cells from human umbilical veins and 7.52 +/- 0.84 mU/10(6) endothelial cells from human pulmonary arteries. Intracellular kinin concentrations were 424 +/- 83 pg/10(6) cells in endothelial cells from human umbilical veins and 576 +/- 146 pg/10(6) cells in endothelial cells from human pulmonary arteries, and they increased in a time-dependent manner after homogenisation. The increase was abolished by aprotinin (1000 kIU), an inhibitor of tissue kallikrein in both cell types. Addition of exogenous kallikrein (5 mU) to homogenised cells led to a five fold increase of kinin concentrations after five minutes, indicating a sufficient resource of cellular kininogen. Removal of extracellularly bound kininogen by washing with dextran sulphate (100 mg/l) resulted in an approximately 75% reduction of the cellular kinin release.(ABSTRACT TRUNCATED AT 250 WORDS)

Urinary kallikrein excretion in Type 1 (insulin-dependent) diabetes mellitus

Kidney haemodynamics appear to change after the early phases of diabetic nephropathy: increases in glomerular filtration rate and in renal plasma flow have been widely reported, while kidney size is increased. As the renal kallikrein-kinin system has been demonstrated to regulate kidney blood circulation, we have evaluated the excretion of urinary kallikrein in 87 Type 1 (insulin-dependent) diabetic patients with and without hyperfiltration. Urinary kallikrein excretion was measured in 24-h urine collections. The esterolytic activity was determined by fluorimetric assay. The excretion of urinary kallikreins was significantly higher in hyperfiltering patients (472 +/- 125 esterase units/24 h) than in normofiltering (168 +/- 77 esterase units/24 h) and control subjects (151 +/- 39 esterase units/24 h), p < 0.001. Furthermore, we observed a positive correlation between urinary kallikrein excretion and glomerular filtration rate (r = 0.785). These data suggest that variations of kallikrein and kinin concentrations may play a role in the alteration of renal haemodynamics in Type 1 diabetes. It is possible that the kinin-kallikrein system, the renin-angiotensin system and the prostaglandins may interact to determine the haemodynamic alterations which are present in the diabetic disease.

Mechanisms of metabisulfite-induced bronchoconstriction: evidence for bradykinin B2-receptor stimulation.

Sodium metabisulfite (MBS) is a food preservative that can trigger bronchoconstriction in asthmatic subjects. Previous studies designed to identify the mechanisms involved in this response have yielded conflicting results. We noted certain similarities between the pharmacology of MBS-induced airway responses and those elicited by bradykinin (BK), another provocating agent in asthmatic subjects. Therefore we used allergic sheep to determine whether MBS-induced bronchoconstriction 1) had a pharmacology similar to that previously seen with BK in this model, including protection by a BK B2-receptor antagonist, NPC-567, and 2) was associated with increased concentrations of immunoreactive kinins in bronchoalveolar lavage. We measured specific lung resistance before and immediately after inhaled buffer and increasing concentrations of MBS (30 breaths of 25, 50, and 100 mg/ml) and calculated the concentration producing 100% increase in specific lung resistance over baseline (PC100). In seven sheep, geometric mean control PC100 was 33.1 mg/ml. Pretreatment with either the anticholinergic agent ipratropium bromide (180 micrograms; PC100 87.1 mg/ml) or the antiasthma drug nedocromil sodium (1 mg/kg aerosol; PC100 97.7 mg/ml) blocked the MBS-induced bronchoconstriction (P less than 0.05), whereas the histamine H1-receptor antagonist chlorpheniramine (2 mg/kg iv) was ineffective. Furthermore the MBS-induced bronchoconstriction was not affected by the neutral endopeptidase inhibitor thiorphan (40 breaths of a 1 mg/ml solution) or the angiotensin-converting enzyme inhibitor enalaprilat (2.5 mg aerosol). In six sheep the MBS-induced bronchoconstriction was completely blocked by NPC-567 (20 breaths, 5 mg/ml aerosol): after treatment with NPC-567 mean PC100 was 100 mg/ml compared with 57.5 mg/ml in the control trial (P less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Role of Endothelial Cells in Inflammatory Processes.

We have studied human umbilical vein (HUVEC) and bovine aortic endothelial cells (BAEC) for the presence of elements of the kinin-kallikrein system. Kinin generation was measured in homogenates of endothelial cells using a radioimmunoassay with a human bradykinin antibody; it was measured after homogenization and was constant over a time interval of 120 min. Addition of exogenous kallikrein (50 mU) led to a five fold increase in kinin concentrations after 5 min in the homogenates, which declined within 2 h. Pretreatment of BAEC with dextran sulfate (0.1 mg/ml) resulted in a 80% reduction in kinin generation. Staining of endothelial cells using an antiserum against glandular kallikrein showed kallikrein immunoreactivity in all cells. Glandular kallikrein activity was measured in homogenates by a colorimetric method. Activities of 3.5 ± 0.4 mU/106 cells in HUVEC and 7.5 ± 0.8 mU/106 cells in BAEC were detected. These data indicate the presence of all key elements of the kinin-kallikrein system in the vascular endothelium. Thus, our results support the existence of a local kallikrein-kinin system in the vascular wall which may contribute to the regulation of local inflammatory processes and the regulation of vascular tone.

Captopril improves neurologic outcome from incomplete cerebral ischemia in rats.

We investigated the effects of the angiotensin-converting enzyme inhibitor captopril on neurologic outcome in a rat model of incomplete cerebral ischemia. Twenty male Sprague-Dawley rats were anesthetized with 70% nitrous oxide in oxygen and fentanyl (10 micrograms x kg-1 i.v. bolus, 25 micrograms x kg-1 x hr-1 i.v. continuous infusion). Animals in group 1 (n = 10) received no angiotensin-converting enzyme inhibitor while animals in group 2 (n = 10) were given 10 mg x kg-1 i.v. captopril 30 minutes prior to the ischemic period. Ischemia was produced by unilateral carotid artery ligation and hemorrhagic hypotension to 35 mm Hg for 30 minutes. Body temperature, arterial blood gases, and arterial pH were maintained constant. Neurologic outcome was evaluated every 24 hours for 3 days using a graded deficit score (0, normal; 18, stroke-related death). On the third day after ischemia, captopril significantly improved neurologic outcome (median deficit score = 4) compared with controls (median deficit score = 18) (p less than 0.05). These results suggest that reduced angiotensin II levels or increased tissue kinin concentrations may decrease ischemic brain injury.

Enhanced contractility of the rat stomach during suppression of angiotensin converting enzyme by captopril in vitro

1. Intragastric pressure (IGP) was used as an index, of the effect of serosal application of captopril (SQ 14,225; D-3-mercapto-2-methylpropanoyl-L-proline) on the contractility of rat stomach in vitro. 2. Captopril, at concentrations greater than 0.3 microM, enhanced the spontaneous gastric motility (GM) in a concentration-dependent manner whereas concentrations less than 0.3 microM selectively potentiated 4 nM bradykinin (BK)-evoked gastric contractions without significantly affecting the spontaneous GM. 3. The kallikrein inhibitor, aprotinin (100 u ml-1), markedly antagonized the enhanced GM to 1.4 microM captopril and BK (4 nM)-evoked contractions, without affecting the contractions evoked by angiotensin 1 (10 nM) and acetylcholine (0.4 microM). The angiotensin II antagonist, saralasin (50 microM) failed to mimic aprotinin. 4. The enhanced GM to captopril was markedly inhibited by tetrodotoxin (1 microM), and partially inhibited by atropine (1 microM). 5. These results indicate that in vitro, captopril (greater than 0.3 microM) enhances gastric contractility through kininase/ACE inhibitory action, presumably by increasing the concentration of undegraded tissue kinins and substance P. This motor response seems to be predominantly due to activation of the cholinergic neurones but non-cholinergic excitatory neurones are also involved.

アレルギー性鼻炎患者におけるケミカル・メディエーターに関する研究 第二報 二相性反応の鼻汁中ヒスタミン，ロイコトリエン，キニンに関する検討

In order to clarify the details of a late phase response (LPR) in allergic rhinitis, serial changes of nasal symptoms and concentration of chemical mediators (histamine, leukotriene (LT) C4 and kinins) in nasal lavage fluid were investigated after the nasal antigen challenge in ten patients with perennial allergic rhinitis with a positive intradermal skin reaction to mite extract. Samples were collected periodically for 8 hours following the challenge. Nasal airway resistance (NAR) and clinical symptoms were also recorded serially. Three out of ten patients showed only early phase response (EPR) and the other seven patients showed both early and late phase response after the challenge. The chief nasal symptom in LPR was nasal obstruction. In EPR, concentrations of chemical mediators in the nasal lavage fluid always increased. In dual (early and late) phase responders, increases of chemical mediators in nasal lavage fluids were notable during both early and late phase responses. In EPR, there was a significant correlation between severity of sneezing attack and concentration of histamine. In LPR, increase of LTC4 level was significantly correlated with the increase of NAR. RAST score and daily nasal symptoms tended to be higher and more sever in dual phase responders compared with early phase responders. We suggest that the amounts of released chemical mediators during allergic reaction denoted the LPR in allergic rhinitis patients.

A Randomized Controlled Trial of Glucocorticoid Prophylaxis against Experimental Rhinovirus Infection

The effects of combined intranasal and systemic glucocorticoid steroids on the local inflammatory response, and symptoms due to experimental rhinovirus infection were studied in 45 adults randomized to prophylaxis with either placebo or steroids. Intranasal beclomethasone (168 micrograms twice a day) was begun 4 days before viral challenge and continued 5 days after challenge. Oral prednisone (30 mg twice daily) was given for 3 days beginning 1 day before challenge. During the first 48 h after viral inoculation, nasal obstruction, nasal mucus weights, and kinin concentrations in nasal lavages were lower in steroid recipients, but subsequent increases in these variables in the steroid group resulted in no significant cumulative differences between treatment groups. These data suggest that steroid prophylaxis may suppress nasal inflammation and cold symptoms during the first 2 days in experimental rhinovirus colds.

アレルギー性鼻炎患者におけるケミカル・メディエーターに関する研究 （第一報） 即時相反応の鼻汁中ヒスタミン，ロイコトリエン，キニンに関する検討

For the purpose of studying the roles of chemical mediators during early phase response of allergic rhinitis, the levels of histamine, leukotriene C4 (LTC4) and kinins in the nasal lavage fluid were measured before and after the nasal challenges with antigens. Seventeen patients with perennial allergic rhinitis with positive intradermal skin reactions to mite antigen extracts were included in this study. The nasal samples were obtained both by aspirating and instilling 5 ml of saline into patient's nostrils before and ten minutes after the nasal challenges. After the nasal challenge with control disk, the concentration of histamine in the nasal samples increased, and the concentrations of LTC4 and kinins did not increase significantly. After the nasal challenges with mite or house dust disk, the concentration of histamine increased as much the same as that after the nasal challenges with control disk, and the concentrations of LTC4 and kinins increased significantly compared with those after the nasal challenges with control disk. delta histamine and delta kinins (delta: net increments in the concentrations after the nasal challenge with antigen over values before the nasal challenge) were significantly correlated with delta albumin. The patients with severe nasal symptoms tended to present more remarkable net increments of chemical mediators than the patients with mild and moderate nasal symptoms. Similar tendencies were recognized in the relationships between the severity of nasal symptoms provoked by nasal challenge with antigen and net increments of chemical mediators. We suggest that the amounts of chemical mediators during the allergic reaction denoted the severity of nasal symptoms in allergic rhinitis patients.