Relationship between chronotropic incompetence and ß-blockers based on changes in chronotropic response during cardiopulmonary exercise testing.

BACKGROUND: Chronotropic incompetence (CI), an attenuated heart rate (HR) response to exercise, is common in patients with cardiovascular disease. The aim of this study was to assess changes in the chronotropic response (CR) during cardiopulmonary exercise testing (CPET) in patients undergoing cardiac rehabilitation and investigate the effects of ß-blockers. METHODS: Patients undergoing cardiac rehabilitation performed CPET. Failure to achieve 80% of the age-predicted maximal HR (APMHR) defined CI. Values of the metabolic chronotropic relationship (MCR) were calculated from the ratio of the HR reserve to metabolic reserve at 4 stages, warm-up (MCR-Wu), anaerobic threshold (MCR-AT), respiratory compensation (MCR-Rc), and peak point (MCR-Pk), using the Wilkoff model. In patients who showed an increase in MCR at ≥ 3 of the 4 exercise stages, CR was considered to have improved. RESULTS: Patients with high BNP levels (≥ 80 pg/ml) had a lower MCR at all stages compared with those with low BNP levels (< 80 pg/ml). Of the 80 patients, 47 showed an increase in both peak VO2 and AT, and of these 31 (66.0%) were taking ß-blockers. Improvement in CR was observed in 30 of 47 patients with CI, and 70% of these were taking ß-blockers. In patients not taking ß-blockers, MCR-AT was lower than MCR-Rc, whereas in those taking ß-blockers MCR-AT was higher than MCR-Rc. CONCLUSIONS: An attenuated HR response may occur during the early stages of exercise. The HR response according to the presence or absence of ß-blockers is clearly identifiable by comparing MCR-AT and MCR-Rc using the Wilkoff model.

Cardiac output response to exercise in chronic cardiac failure patients.

The purpose of this study was to investigate the precise pattern of stroke volume (SV) response during exercise in patients with chronic heart failure (CHF) compared with age-matched controls. Fourteen patients with CHF and 7 controls performed symptom-limited bicycle exercise testing with respiratory gas exchange measurement. Patients were classified into group A (n = 7) with peak VO2 ≥ 18.0 mL/kg/minute and group B (n = 7) with peak VO2 < 18.0 mL/kg/ minute. SV and cardiac output (CO) were continuously measured during exercise using a novel thoracic impedance method (Physioflow). CO and SV were lower in the group B patients than those in controls at peak exercise [CO: 11.3 ± 1.0 (SE) versus 15.6 ± 0.9 L/minute, P < 0.05, SV: 89 ± 6 versus 110 ± 6 mL, P < 0.05]. SV reached its peak levels during submaximal exercise and remained close to the peak value until peak exercise in 6 of 7 group B patients (86%). On the other hand, it progressively increased until peak exercise in 6 of 7 controls (86%) and 5 of 7 group A patients (71%). In all subjects, CO at peak exercise was more closely correlated with SV at peak exercise (r = 0.86, P < 0.001) than with peak heart rate (r = 0.69, P < 0.001). CHF patients with impaired exercise capacity had attenuated increment of CO during exercise, and SV reached its peak levels during submaximal exercise.

Cardiac rehabilitation decreases plasma pentraxin 3 in patients with cardiovascular diseases.

BACKGROUND: Inflammatory markers such as serum C-reactive protein (CRP), serum amyloid A (SAA), and plasma pentraxin 3 (PTX3), which belong to the pentraxin superfamily, increase due to various inflammatory diseases. Some studies demonstrated that serum CRP and SAA are predictors of cardiovascular diseases, and cardiac rehabilitation (CR) induces anti-inflammatory effects. In the present study, we investigated the effects of CR on pentraxins (serum CRP, SAA, and plasma PTX3) in patients with cardiovascular diseases. METHODS: Fifty patients with cardiovascular diseases [61 ± 13 (mean ± SD) years old, male/female 44/6] participated. Each subject performed CR using aerobic bicycle exercise two or three times per week for 3-6 months. We measured resting serum high-sensitivity CRP (hsCRP), SAA, and plasma PTX3 before and 3 and 6 months after CR, and compared them with VO(2peak) determined using a standard increment cycle ergometer protocol, B-type natriuretic peptide (BNP), and other biochemical data such as HbA1c. RESULTS: There was a significant positive correlation between hsCRP and SAA (r = 0.92, p < 0.001), but no relations between these parameters and PTX3. Plasma PTX3 significantly decreased time dependently during CR (at baseline 3.2 ± 2.0 ng/ml, at 3 months 2.3 ± 0.8 ng/ml, at 6 months 2.1 ± 0.7 ng/ml; all p < 0.05). Serum hsCRP tended to decrease, but not statistically significantly. At baseline, plasma PTX3 was negatively correlated with the percentage of the predicted values of VO(2peak) and positively correlated with BNP. CR significantly increased the percentage of the predicted values of VO(2peak) and decreased BNP. CONCLUSIONS: Plasma PTX3, an inflammatory marker, which was quite different from CRP and SAA, decreased during cardiac rehabilitation with an improvement of exercise capacity in patients with cardiovascular diseases.

Pentraxin3 and high-sensitive C-reactive protein are independent inflammatory markers released during high-intensity exercise.

High-intensity exercise shares similarities with acute phase responses of inflammatory diseases. We investigated the influences of acute exercise on inflammatory markers, plasma pentraxin3 (PTX3) and serum high-sensitive C-reactive protein (CRP) (hsCRP). Nine healthy male subjects (41 ± 3 years old) participated. Each subject performed three types of exercise; ergometer exercise at 70% workload of anaerobic threshold (AT) for 30 min (70% AT exercise), peak ergometer exercise (peak EX, 20 watt increase/min until fatigue) and resistance exercises of 70% 1 RM (70% RE) until exhaustion. We measured plasma PTX3, serum hsCRP, lactate, noradrenaline (NOR), white blood cells (WBC), interleukin-6 (IL-6) and myeloperoxidase (MPO), a marker of neutrophil degranulation. The effects of exercise on intracellular PTX3 and MPO in neutrophils were also investigated, by using flow cytometry analysis. Circulating PTX3 and hsCRP significantly increased immediately after 70% RE and peak EX, while they did not increase after 70% AT exercise. The exercise-induced fold increase in PTX3 and hsCRP relative to the resting level was positively correlated with the changes in WBC, NOR, lactate and MPO. The exercise-induced fold increase in IL-6 was positively correlated with that in NOR, but not with that in PTX3 and hsCRP. Neutrophils isolated immediately after 70% RE, but not 70% AT exercise, exhibited lower mean fluorescence for PTX3 and MPO than those from pre-exercise blood. These results provide the evidence that high-intensity exercises significantly increase circulatory PTX3 as well as hsCRP. The release from peripheral neutrophils is suggested to be involved in the exercise-induced plasma PTX3 increase.

Involvement of CaV3.1 T-type calcium channels in cell proliferation in mouse preadipocytes.

Voltage-gated Ca(2+) channels (Ca(V)) are ubiquitously expressed in various cell types and play vital roles in regulation of cellular functions including proliferation. However, the molecular identities and function of Ca(V) remained unexplored in preadipocytes. Therefore, whole cell voltage-clamp technique, conventional/quantitative real-time RT-PCR, Western blot, small interfering RNA (siRNA) experiments, and immunohistochemical analysis were applied in mouse primary cultured preadipocytes as well as mouse 3T3-L1 preadipocytes. The effects of Ca(V) blockers on cell proliferation and cell cycle were also investigated. Whole cell recordings of 3T3-L1 preadipocytes showed low-threshold Ca(V), which could be inhibited by mibefradil, Ni(2+) (IC(50) of 200 muM), and NNC55-0396. Dominant expression of alpha(1G) mRNA was detected among Ca(V) transcripts (alpha(1A)-alpha(1I)), supported by expression of Ca(V)3.1 protein encoded by alpha(1G) gene, with immunohistochemical studies and Western blot analysis. siRNA targeted for alpha(1G) markedly inhibited Ca(V). Dominant expression of alpha(1G) mRNA and expression of Ca(V)3.1 protein were also observed in mouse primary cultured preadipocytes. Expression level of alpha(1G) mRNA and Ca(V)3.1 protein significantly decreased in differentiated adipocytes. Mibefradil, NNC55-0396, a selective T-type Ca(V) blocker, but not diltiazem, inhibited cell proliferation in response to serum. NNC55-0396 and siRNA targeted for alpha(1G) also prevented cell cycle entry/progression. The present study demonstrates that the Ca(V)3.1 T-type Ca(2+) channel encoded by alpha(1G) subtype is the dominant Ca(V) in mouse preadipocytes and may play a role in regulating preadipocyte proliferation, a key step in adipose tissue development.

Venous blood gas and metabolite response to low-intensity muscle contractions with external limb compression.

The effect of low-intensity resistance exercise with external limb compression (100 [EC100] and 160 [EC160] mm Hg) on limb blood flow and venous blood gas-metabolite response was investigated and compared with that of high-intensity resistance exercise (no external compression). Unilateral elbow flexion muscle contractions were performed at 20% (75 repetitions, 4 sets, 30-second rest intervals) and 70% of 1-repetition maximum (1-RM; 3 sets, each set was until failure, 3-minute rest intervals). Precontraction brachial arterial blood flow (Doppler ultrasound) was reduced with EC100 or EC160 (56% and 39% of baseline value, respectively) compared with no external compression (control). At 20% 1-RM, brachial arterial blood flow increased after contractions performed with EC160 (190%), but not with the others. Decreases in venous oxygen partial pressure (P(v)O(2)) and venous oxygen saturation (S(v)O(2)) were greater during EC100 and EC160 than control (mean [SE]: P(v)O(2), 28 [3] vs 26 [2] vs 33 [2] mm Hg; S(v)O(2), 41% [5%] vs 34% [4%] vs 52% [5%], respectively). Changes in venous pH (pH(v)), venous carbon dioxide partial pressure (P(v)CO(2)), and venous lactate concentration ([L(-)](v)) were greater with EC160 than EC100 and/or control (pH(v), 7.19 [0.01] vs 7.25 [0.01] vs 7.27 [0.02]; P(v)CO(2), 72 [3] vs 64 [2] vs 60 [3] mm Hg; [L(-)](v), 5.4 [0.6] vs 3.7 [0.4] vs 3.0 [0.4] mmol/L, respectively). Seventy percent 1-RM contractions resulted in greater changes in pH(v) (7.14 [0.02]), P(v)CO(2) (91 [5] mm Hg), and [L(-)](v) (7.0 [0.5] mmol/L) than EC100 and EC160, but P(v)O(2) (30 [4] mm Hg) and S(v)O(2) (40% [3%]) were similar. In conclusion, changes in pH(v), P(v)CO(2), and [L(-)](v), but not in P(v)O(2) and S(v)O(2), are sensitive to changes in relative, "internal" intensity of low-intensity muscle contractions caused by reduced blood flow (EC160) or high-intensity muscle contractions. Given the magnitude of the changes in pH(v), P(v)CO(2), and [L(-)](v), it appears plausible that they may be involved in stimulating the observed increase in muscle activation via group III and IV afferents.

Effects of low-intensity resistance exercise with blood flow restriction on coagulation system in healthy subjects.

Recent studies have demonstrated that even a low-intensity resistance exercise can effectively induce muscle hypertrophy and strength increase when combined with moderate blood flow restriction (BFR) into the exercising muscle. Although serious side effects of low-intensity resistance exercise with BFR have not been reported, a concern of thrombosis has been suggested, because this type of exercise is performed with restricted venous blood flow and pooling of blood in extremities. Thus, the purpose of this study was to investigate the effects of low-intensity resistance exercise with BFR on coagulation system in healthy subjects. Ten healthy men (25.1 +/- 2.8 year) performed four sets of leg press exercises with and without BFR (150-160 mmHg) at an intensity of 30% of one-repetition maximum (1RM). In each exercise session, one set with 30 repetitions was followed by three sets with 15 repetitions. Blood samples were taken before, and 10 min, 1, 4 and 24 h after the exercise. Prothrombin fragment 1 + 2 (PTF) and thrombin-antithrombin III complex (TAT) were measured as markers of thrombin generation, whereas D-dimer and fibrin degradation product (FDP) were measured as markers of intravascular clot formation. Changes in plasma volume (PV) were calculated from haemoglobin and hematocrit values. PV reduction was significantly greater after the exercise with BFR than without (P<0.05). However, neither markers of thrombin generation nor intravascular clot formation increased after the exercises. These results suggest that low-intensity resistance exercise with BFR does not activate coagulation system in healthy subjects.

Function and role of voltage-gated sodium channel NaV1.7 expressed in aortic smooth muscle cells.

Voltage-gated Na(+) channel currents (I(Na)) are expressed in several types of smooth muscle cells. The purpose of this study was to evaluate the expression of I(Na), its functional role, pathophysiology in cultured human (hASMCs) and rabbit aortic smooth muscle cells (rASMCs), and its association with vascular intimal hyperplasia. In whole cell voltage clamp, I(Na) was observed at potential positive to -40 mV, was blocked by tetrodotoxin (TTX), and replacing extracellular Na(+) with N-methyl-d-glucamine in cultured hASMCs. In contrast to native aorta, cultured hASMCs strongly expressed SCN9A encoding Na(V)1.7, as determined by quantitative RT-PCR. I(Na) was abolished by the treatment with SCN9A small-interfering (si)RNA (P < 0.01). TTX and SCN9A siRNA significantly inhibited cell migration (P < 0.01, respectively) and horseradish peroxidase uptake (P < 0.01, respectively). TTX also significantly reduced the secretion of matrix metalloproteinase-2 6 and 12 h after the treatment (P < 0.01 and P < 0.05, respectively). However, neither TTX nor siRNA had any effect on cell proliferation. L-type Ca(2+) channel current was recorded, and I(Na) was not observed in freshly isolated rASMCs, whereas TTX-sensitive I(Na) was recorded in cultured rASMCs. Quantitative RT-PCR and immunostaining for Na(V)1.7 revealed the prominent expression of SCN9A in cultured rASMCs and aorta 48 h after balloon injury but not in native aorta. In conclusion, these studies show that I(Na) is expressed in cultured and diseased conditions but not in normal aorta. The Na(V)1.7 plays an important role in cell migration, endocytosis, and secretion. Na(V)1.7 is also expressed in aorta after balloon injury, suggesting a potential role for Na(V)1.7 in the progression of intimal hyperplasia.

Hemodynamic responses to simulated weightlessness of 24-h head-down bed rest and KAATSU blood flow restriction.

The KAATSU training is a unique method of muscle training with restricting venous blood flow, which might be applied to prevent muscle atrophy during space flight, but the effects of KAATSU in microgravity remain unknown. We investigated the hemodynamic responses to KAATSU during actually simulated weightlessness (6 degrees head-down tilt for 24 h, n = 8), and compared those to KAATSU in the seated position before bed rest. KAATSU was applied to the proximal ends of both the thighs. In the seated position before bed rest, sequential incrementing of KAATSU cuff pressure and altering the level of blood flow restriction resulted in a decrease in stroke volume (SV) with an increase in heart rate (HR). KAATSU (150-200 mmHg) decreased SV comparable to standing. Following 24-h bed rest, body mass, blood volume (BV), plasma volume (PV), and diameter of the inferior vena cava (IVC) were significantly reduced. Norepinephrine (NOR), vasopressin (ADH), and plasma renin activity (PRA) tend to be reduced. A decrease in SV and CO induced by KAATSU during the simulated weightlessness was larger than that in the seated position before bed rest, and one of eight subjects developed presyncope due to hypotension during 100 mmHg KAATSU. High-frequency power (HF(RR)) decreased during KAATSU and standing, while low-frequency/high-frequency power (LF(RR)/HF(RR)) increased significantly. NOR, ADH and PRA also increased during KAATSU. These results indicate that KAATSU blood flow restriction reproduces the effects of standing on HR, SV, NOR, ADH, PRA, etc., thus stimulating a gravity-like stress during simulated weightlessness. However, syncope due to lower extremity blood pooling and subsequent reduction of venous return may be induced during KAATSU in microgravity as reported in cases of lower-body negative pressure.

Effect of dexamethasone on voltage-gated Na+ channel in cultured human bronchial smooth muscle cells.

Voltage-gated Na(+) channel (I(Na)) encoded by SCN9A mRNA is expressed in cultured human bronchial smooth muscle cells. We investigated the effects of dexamethasone on I(Na), by using whole-cell voltage clamp techniques, reverse transcriptase/polymerase chain reaction (RT-PCR), and quantitative real-time RT-PCR. Acute application of dexamethasone (10(-6) M) did not affect I(Na). However, the percentage of the cells with I(Na) was significantly less in cells pretreated with dexamethasone for 48 h, and the current-density of I(Na) adjusted by cell capacitance in cells with I(Na) was also decreased in cells treated with dexamethasone. RT-PCR analysis showed that alpha and beta subunits mRNA of I(Na) mainly consisted of SCN9A and SCN1beta, respectively. Treatment with dexamethasone for 24-48 h inhibited the expression of SCN9A mRNA. The inhibitory effect of dexamethasone was concentration-dependent, and was observed at a concentration higher than 0.1 nM. The effect of dexamethasone on SCN9A mRNA was not blocked by spironolactone, but inhibited by mifepristone. The inhibitory effects of dexamethasone on SCN9A mRNA could not be explained by the changes of the stabilization of mRNA measured by using actinomycin D. These results suggest that dexamethasone inhibited I(Na) encoded by SCN9A mRNA in cultured human bronchial smooth muscle cells by inhibiting the transcription via the glucocorticoid receptor.

Hemodynamic and neurohumoral responses to the restriction of femoral blood flow by KAATSU in healthy subjects.

The application of an orthostatic stress such as lower body negative pressure (LBNP) has been proposed to minimize the effects of weightlessness on the cardiovascular system and subsequently to reduce the cardiovascular deconditioning. The KAATSU training is a novel method to induce muscle strength and hypertrophy with blood pooling in capacitance vessels by restricting venous return. Here, we studied the hemodynamic, autonomic nervous and hormonal responses to the restriction of femoral blood flow by KAATSU in healthy male subjects, using the ultrasonography and impedance cardiography. The pressurization on both thighs induced pooling of blood into the legs with pressure-dependent reduction of femoral arterial blood flow. The application of 200 mmHg KAATSU significantly decreased left ventricular diastolic dimension (LVDd), cardiac output (CO) and diameter of inferior vena cava (IVC). Similarly, 200 mmHg KAATSU also decreased stroke volume (SV), which was almost equal to the value in standing. Heart rate (HR) and total peripheral resistance (TPR) increased in a similar manner to standing with slight change of mean blood pressure (mBP). High-frequency power (HF(RR)) decreased during both 200 mmHg KAATSU and standing, while low-frequency/high-frequency power (LF(RR)/HF(RR)) increased significantly. During KAATSU and standing, the concentration of noradrenaline (NA) and vasopressin (ADH) and plasma renin activity (PRA) increased. These results indicate that KAATSU in supine subjects reproduces the effects of standing on HR, SV, TPR, etc., thus stimulating an orthostatic stimulus. And, KAATSU training appears to be a useful method for potential countermeasure like LBNP against orthostatic intolerance after spaceflight.

Comparative effects of azelnidipine and other Ca2+-channel blockers on the induction of inducible nitric oxide synthase in vascular smooth muscle cells.

Overproduction of nitric oxide by inducible nitric oxide synthase contributes to the progression of cardiovascular disease. We investigated the effects of azelnidipine and other Ca2+-channel blockers on nitric oxide production by cultured aortic smooth muscle cells isolated from Wistar rats and human umbilical vein endothelial cells (HUVECs), using the Griess reaction and oxyhemoglobin method. Release of lactic dehydrogenase (LDH) was measured to evaluate cell damage, and immunohistochemistry was performed to examine the expression of inducible nitric oxide synthase and nitrotyrosine protein. Azelnidipine and other Ca2+-channel blockers inhibited the release of nitric oxide induced by lipopolysaccharide plus interferon-gamma. Azelnidipine inhibited it most potently among the Ca2+-channel blockers tested (azelnidipine, amlodipine, nifedipine, diltiazem, verapamil, and nicardipine) at a concentration of 10 microM. Longer stimulation with these agents induced the expression of inducible nitric oxide synthase and nitrotyrosine, with an increase of lactic dehydrogenase release, whereas azelnidipine suppressed these changes. In human umbilical vein endothelial cells, azelnidipine enhanced basal nitric oxide production by endothelial nitric oxide synthase. In conclusion, azelnidipine potently inhibited the induction of inducible nitric oxide synthase and then nitric oxide production in vascular smooth muscle cells, while enhancing constitutive nitric oxide production by endothelial cells. Azelnidipine may inhibit nitrotyrosine expression and cell damage caused by overproduction of nitric oxide, suggesting a mechanism for its cardiovascular protective effect.

Amiodarone and N-desethylamiodarone enhance endothelial nitric oxide production in human endothelial cells.

Amiodarone (AM) is a potent vasodilator and exhibits diverse cardiovascular protective effects in vivo, but their underlying mechanisms remain unsettled. We investigated the effects of AM and N-desethylamiodarone (DEA), the major metabolite of AM, on endothelial nitric oxide (NO) production using cultured human umbilical vein endothelial cells (HUVECs). The release of NO was evaluated as measured by nitrite, a stable metabolite of NO, using the Griess reaction and also measured directly by a NO-selective electrode. The expression of each nitric oxide synthase (NOS) mRNA was examined by reverse transcriptase-polymerase chain reaction (RT-PCR), and the effects of AM on eNOS mRNA expression were studied by quantitative real-time RT-PCR. AM and DEA (1-30 microM) enhanced NO production in a concentration-dependent manner. DEA was capable of producing more NO than AM. L-NAME, a nonselective NOS inhibitor, EGTA, a Ca(2+)-chelating agent, and nickel, a nonspecific Ca(2+) blocker, all inhibited AM-induced NO production. However, LY294002, an Akt pathway inhibitor and SB202190, a MAP kinase inhibitor, did not significantly suppress the production. In RT-PCR analysis, only eNOS mRNA was detected. Treatment with AM for 4 hours did not show a significant increase in the expression of eNOS mRNA. AM lower than 30 microM did not induce apoptosis, net cell loss, or LDH release from cells. The present study provides the first evidence that therapeutic concentrations of AM and DEA enhance eNOS-mediated NO production without any toxic or apoptotic effects. This mechanism may underlie the cardiovascular protective effects of AM and its metabolite observed in a clinical setting.

Hemodynamic and hormonal responses to a short-term low-intensity resistance exercise with the reduction of muscle blood flow.

We investigated the hemodynamic and hormonal responses to a short-term low-intensity resistance exercise (STLIRE) with the reduction of muscle blood flow. Eleven untrained men performed bilateral leg extension exercise under the reduction of muscle blood flow of the proximal end of both legs pressure-applied by a specially designed belt (a banding pressure of 1.3 times higher than resting systolic blood pressure, 160-180 mmHg), named as Kaatsu. The intensity of STLIRE was 20% of one repetition maximum. The subjects performed 30 repetitions, and after a 20-seconds rest, they performed three sets again until exhaustion. The superficial femoral arterial blood flow and hemodynamic parameters were measured by using the ultrasound and impedance cardiography. Serum concentrations of growth hormone (GH), vascular endothelial growth factor (VEGF), noradrenaline (NE), insulin-like growth factor (IGF)-1, ghrelin, and lactate were also measured. Under the conditions with Kaatsu, the arterial flow was reduced to about 30% of the control. STLIRE with Kaatsu significantly increased GH (0.11+/-0.03 to 8.6+/-1.1 ng/ml, P < 0.01), IGF-1 (210+/-40 to 236+/-56 ng/ml, P < 0.01), and VEGF (41+/-13 to 103+/-38 pg/ml, P < 0.05). The increase in GH was related to neither NE nor lactate, but the increase in VEGF was related to that in lactate (r = 0.57, P < 0.05). Ghrelin did not change during the exercise. The maximal heart rate (HR) and blood pressure (BP) in STLIRE with Kaatsu were higher than that without Kaatsu. Stroke volume (SV) was lower due to the decrease of the venous return by Kaatsu, but, total peripheral resistance (TPR) did not change significantly. These results suggest that STLIRE with Kaatsu significantly stimulates the exercise-induced GH, IGF, and VEGF responses with the reduction of cardiac preload during exercise, which may become a unique method for rehabilitation in patients with cardiovascular diseases.

Ursodeoxycholic acid inhibits endothelin-1 production in human vascular endothelial cells.

Endothelin-1 is known to be implicated in the pathogenesis of hepatobiliary diseases such as cirrhosis, especially in portal hypertension. This study aimed to investigate the effects of ursodeoxycholic acid on endothelin-1 production in human endothelial cells. The effects of ursodeoxycholic acid and its conjugates (tauroursodeoxycholic and glycoursodeoxycholic acids) on endothelin-1 production as well as nitric oxide (NO) in human umbilical vein endothelial cells (HUVECs) were examined. The production of endothelin-1 and nitric oxide in culture medium was measured using enzyme-linked immunosorbent assay (ELISA) and the Griess method, respectively. Endothelin-1 and endothelial nitric oxide synthase (eNOS) mRNA expression were investigated by real-time quantitative reverse transcriptase/polymerase chain reaction (RT-PCR). Ursodeoxycholic acid (30-1000 microM) inhibited endothelin-1 production in a concentration-dependent manner, and ursodeoxycholic acid at concentrations higher than 300 microM increased nitric oxide production in culture medium. The conjugates of ursodeoxycholic acid also increased nitric oxide production and decreased endothelin-1 production, which was less effective than ursodeoxycholic acid. N-nitro-L-arginine-mythel-ester (L-NAME), a nitric oxide synthase (NOS) inhibitor, suppressed the ursodeoxycholic acid-induced nitric oxide production, but it did not antagonize the inhibitory effects of ursodeoxycholic acid on endothelin-1 production. Ursodeoxycholic acid also induced a concentration-dependent decrease in endothelin-1 mRNA expression without significant changes in eNOS mRNA expression. These results provide novel evidence that ursodeoxycholic acid inhibits endothelin-1 production in human endothelial cells, but nitric oxide is not responsible for the inhibitory effect of ursodeoxycholic acid on endothelin-1. Thus, ursodeoxycholic acid therapy may prevent the development of several pathogenesis such as portal hypertension observed in patients with cirrhosis due to the improvement of endothelial function.

Pulmonary artery obstruction caused by thoracic aortic dissection: a case with unique pathological findings.

Pulmonary artery obstruction is a rare complication of acute thoracic aortic dissection. A 74-year-old woman was admitted to hospital with respiratory distress. Computed tomography scan showed right pulmonary artery occlusion and a thoracic aortic dissection of the Stanford A type. Lung perfusion scan revealed a defect in the entire right lung field. These findings mimicked acute pulmonary thromboembolism accompanying aortic dissection. On the other hand, pulmonary angiography revealed a round smooth defect of the right pulmonary artery, indicating an extrinsic compression. The patient finally died of cardiac tamponade. Autopsy disclosed that the right pulmonary artery was compressed by a hematoma in the adventitial space around the pulmonary artery. Such a mechanism of pulmonary artery obstruction caused by acute aortic dissection is unique, and is distinct from that caused by chronic non-dissecting aortic aneurysms, which themselves compress the pulmonary arteries. This complication inevitably follows aortic rupture; therefore, emergency operation to repair the dissected aorta must be performed to avoid the following catastrophic event.