Regulation of Th17 cell differentiation by intestinal commensal bacteria

Interleukin (IL)-17-producing CD4 T cells ('Th17 cells') are most abundant at the intestinal mucosa, and play a critical role in the maintenance of mucosal barrier function. Recent studies indicate that accumulation of intestinal Th17 cells depends on stimulation by intestinal commensal bacteria – particularly by segmented filamentous bacterium. In this review, we summarise recent advances in our understanding of the mechanisms of intestinal Th17 synthesis in mice, and discuss their relevance to infectious and inflammatory diseases.

Skin application of the nonsteroidal anti-inflammatory drug ketoprofen downmodulates the antigen-presenting ability of Langerhans cells in mice

BACKGROUND

Ketoprofen (KP) is widely used as a topical nonsteroidal anti-inflammatory drug that inhibits prostaglandin (PG) biosynthesis. As PGE(2) upregulates the antigen-presenting activity of Langerhans cells (LCs), i.e. migration to lymph nodes and expression of immunocompetent molecules, modulation of LC functions resulting from topical application of KP is an issue to be clarified.

OBJECTIVES

To investigate the in vivo effect of KP application to the skin and the in vitro effect of KP addition to the culture on the antigen-presenting ability of murine LCs. Methods Ears of BALB/c mice were painted with picryl chloride (PCl) hapten, KP or both. An immunofluorescence study of epidermal sheets and a flow cytometric analysis of epidermal cell suspensions from the treated ears were performed.

RESULTS

PCl altered the morphology of LCs and reduced their number, and simultaneous application of 10% KP maintained LC morphology and number. KP at 5% or 10% clearly decreased the PCl-augmented expression of major histocompatibility complex class II and CD86 on LCs. In cultivation of freshly isolated epidermal cells, 5 mmol L(-1) KP inhibited the culture-promoted expression of these molecules on LCs, whereas 100 micromol L(-1) indomethacin was not inhibitory. The further addition of PGE(2) to the KP-containing epidermal cell culture did not restore the expression of these molecules. Moreover, topical application of 10% KP to the sensitizing sites suppressed the development of contact hypersensitivity to PCl.

CONCLUSIONS

KP may have the potential to inhibit the antigen-presenting ability of LCs, in a PGE(2)-independent manner.

Innate immunity mediated by epidermal keratinocytes promotes acquired immunity involving Langerhans cells and T cells in the skin

Skin is an immunological organ consisting of epidermal cells, i.e. keratinocytes and Langerhans cells (LCs, antigen-presenting dendritic cells), and both innate and acquired immune systems operate upon exposure of the skin to various external microbes or their elements. To explore the relationship between innate and acquired immunities in the skin, we investigated whether Toll-like receptor (TLR) ligation of epidermal cells enhances the ability of LCs to present a specific antigen to T cells in mice. LC-containing epidermal cells were incubated with CpG oligonucleotide (TLR9 ligand) modified with trinitrophenyl hapten, and cultured with hapten-primed CD4(+) T cells. TLR9 ligand was capable of enhancing the hapten-presenting ability of LCs when LC-enriched epidermal cells, but not purified LCs, were used as the LC source, suggesting that bystander keratinocytes play a role in the enhancement of LC function. Cultivation of freshly isolated epidermal cells with CpG promoted the expression of major histocompatibility complex (MHC) class II and CD86 molecules on LCs. CpG enhanced the production of interleukin (IL)-1alpha, granulocyte-macrophage colony-stimulating factor (GM-CSF) and tumour necrosis factor (TNF)-alpha by primarily cultured keratinocytes. The addition of a cocktail of neutralizing antibodies against these cytokines abrogated the CpG-promoted, antigen-presenting ability of LC-enriched epidermal cells. Moreover, the addition of culture supernatants from CpG-stimulated keratinocytes restored the ability of purified LCs. Our study demonstrated that although the direct effect of CpG on LCs is minimal, LC function can be up-regulated indirectly by cytokines released by CpG-stimulated keratinocytes. This also implies that innate immunity evoked by TLR ligation of keratinocytes enhances acquired immunity comprising LCs and T cells.

Molecular and epidemiological study of the first outbreak of vanB type vancomycin-resistant Enterococcus faecalis in Japan

In July, 1999, an outbreak of vancomycin-resistant Enterococcus faecalis (VREF) with the vanB genotype occurred for the first time in Japan at Hokushin General Hospital, Nakano City, Nagano Prefecture. Four VREF strains were isolated from the clinical specimens of four inpatients, and 16 VREF strains were isolated by the screening of asymptomatic carriers and by surveillance of the hospital environment. All of the isolates possessed vanB genes. In a pulsed-field gel electrophoresis analysis, 19 out of 20 VREF isolates exhibited the indistinguishable restriction endonuclease digestion patterns of the chromosomal DNA. Additional investigation by Southern hybridization using the vanB probe implied that the vanB gene of these 19 isolates was encoded on a 110-kb plasmid. These findings indicate that the outbreak was principally caused by a single clone. The restriction endonuclease digestion patterns of the remaining single isolate was different from those of the other isolates. The vanB gene was encoded on the chromosome.

Interaction of ribosome recycling factor and elongation factor EF-G with E. coli ribosomes studied by the surface plasmon resonance technique

BACKGROUND

Ribosome recycling factor (RRF), in concert with elongation factor EF-G, is required for disassembly of the post-termination complex of a ribosome after the release of polypeptides. How RRF dissociates the complex has long been puzzling. Crystal structures of RRF molecules have been solved recently and shown to mimic a transfer RNA (tRNA) shape, which prompted us to examine whether RRF binds to the ribosome as tRNA does.

RESULTS

The formation of ribosome complexes on the surface-coupled RRF and elongation factor EF-G of Escherichia coli was monitored in real time with a BIACORE 2000 instrument based on the surface plasmon resonance technique. RRF interacted with 70S ribosomes as well as 50S and 30S subunits, although it interacted preferentially with 50S subunits, which was clearly seen under high but physiological ionic conditions. This 50S interaction was diminished by a single amino acid substitutions for Arg132 of RRF, which did not appreciably affect the protein folding but nullified the activity in vivo and in vitro. Moreover, a set of antibiotics that inhibited the RRF-50S interaction were also inhibitory to the polysome breakdown activity of RRF in vitro. The BIACORE technique also worked very well in demonstrating the action of the antibiotics thiostrepton and fusidic acid, which are inhibitory to the RRF function by freezing the pre- and post-translocation intermediates catalysed by EF-G.

CONCLUSIONS

These results suggest that the preferential interplay of RRF with the 50S subunit may be of biological significance, probably reflecting the mode of RRF action. The BIACORE technique proved useful for real-time monitoring of the interaction between the ribosome and translation factors, as well as for screening of potential inhibitors for ribosome recycling factor.

Inhibitory effect of heterologous ribosome recycling factor on growth of Escherichia coli

Ribosome recycling factor (RRF) of Thermotoga maritima was expressed in Escherichia coli from the cloned T. maritima RRF gene and purified. Expression of T. maritima RRF inhibited growth of the E. coli host in a dose-dependent manner, an effect counteracted by the overexpression of E. coli RRF. T. maritima RRF also inhibited the E. coli RRF reaction in vitro. Genes encoding RRFs from Streptococcus pneumoniae and Helicobacter pylori have been cloned, and they also impair growth of E. coli, although the inhibitory effect of these RRFs was less pronounced than that of T. maritima RRF. The amino acid sequence at positions 57 to 62, 74 to 78, 118 to 122, 154 to 160, and 172 to 176 in T. maritima RRF differed totally from that of E. coli RRF. This suggests that these regions are important for the inhibitory effect of heterologous RRF. We further suggest that bending and stretching of the RRF molecule at the hinge between two domains may be critical for RRF activity and therefore responsible for T. maritima RRF inhibition of the E. coli RRF reaction.

Purification and characterization of the allergenic components of shimeji mushroom (Tricholoma conglobatum) spore for shimeji workers' hypersensitivity pneumonitis

Respiratory symptoms and hypersensitivity pneumonitis (HP) among mushroom workers have been well documented. Inhalation of shimeji mushroom (Tricholoma conglobatum) spore has been assumed to be the cause of HP among indoor shimeji cultivating workers. We isolated and partially characterized the allergenic components of shimeji. The sera from 9 HP patients, 10 asymptomatic shimeji workers and 15 normal individuals were examined for shimeji specific IgG and IgA antibodies by ELISA using crude shimeji extract. Shimeji specific IgG- and IgA-antibodies were higher in sera from HP patients than in sera from control subjects. Crude shimeji spore extract was separated and purified by HPLC followed by SDS-PAGE, and their antigenic activity was studied by immunoblotting with a pool of sera from patients. Sera from all HP patients showed IgG and IgA antibody activities to 21, 16 and 14 kD proteins extracted from shimeji spore. The 21 kD protein contained internal peptide amino acid sequence of Gly-Gly-Thr-Val-Ile-Asn-Leu-Leu-Gly, Gln-Arg-Phe-Glu-Glu and Gln-Gly-Ile-Tyr. These results demonstrate that shimeji spore extract contains multiple proteinous components, which have antigenic activity to react with the sera from HP patients among shimeji workers. These proteins may be the potent sensitizing allergens to cause HP among shimeji cultivating workers.

Effects of alacepril and amlodipine on the renal injury induced by a high-cholesterol diet in rats

BACKGROUND

A high-cholesterol (HC) diet increases blood pressure and induces renal injury in rats. We compared the effects of alacepril, an ACE inhibitor, and amlodipine, a Ca antagonist, on the renal injury induced by an HC diet in rats.

DESIGN AND METHODS

Male Sprague-Dawley rats were given either an HC diet only (n = 5), an HC diet and amlodipine (n = 10) or an HC diet and alacepril (n = 10). The control rats (n = 5) were given a normal diet Systolic blood pressure (SBP) was measured by a tail-cuff method. Serum lipids, malondialdehyde (MDA) as a parameter for lipid peroxidation and urinary protein excretion were determined at 0, 4 and 8 weeks. The renal injury was evaluated histologically by the glomeruli sclerosing score.

RESULTS

The HC diet increased SBP. Amlodipine lowered SBP more significantly than alacepril. Serum total cholesterol was increased by the HC diet and was not affected by either anti-hypertensive agent. HDL-cholesterol was similarly decreased in the three HC diet groups. Alacepril, but not amlodipine, completely attenuated the MDA elevation induced by the HC diet. Urinary protein excretion was decreased by the two anti-hypertensive agents at a similar rate. The renal histological injury assessed by the sclerosing score was ameliorated more significantly by alacepril than by amlodipine.

CONCLUSIONS

Both amlodipine and alacepril decreased blood pressure and urinary protein, and ameliorated the renal injury induced by the HC diet in rats. The renal effect of alacepril seems to be mediated by the decrease in oxidative stress as well as by reduction of blood pressure, since alacepril lowered the sclerosing score more than amlodipine and completely attenuated MDA, although the blood pressure reduction by alacepril was less than that by amlodipine.

[A case of localized fibrous tumor of the pleura after four years follow up and evaluate the doubling time with computed tomography]

Thirty-five-year female had taken video assisted thoraco-surgery (VATS) and resected her localized fibrous tumor of parietal pleura. She suspected chest tumor with annual X-ray survey for lung disease four years ago. She complained of left side back pain recently. Her chest CT revealed that the tumor enlarged than before. She was performed video assisted thoraco-surgery. The tumor was solid hard and connected to the parietal pleura with pedicle, which was resected easily from her pleural cavity. Histrogical examination detected that her tumor was localized fibrous tumor of parietal pleura. CD 34 and Vimentin were positive and cytokeratin was negative in this case. Four year and two examinations of the chest CT later, we could determine the doubling time (800.7 days) of localized fibrous tumor in this case.

Hypersensitivity pneumonitis among workers cultivating Tricholoma conglobatum (shimeji)

We report five cases of hypersensitivity pneumonitis among workers cultivating Tricholoma conglobatum (shimeji). After having worked for 5 to 20 years, they began to notice symptoms of cough, sputum, and dyspnea. They were diagnosed as having a hypersensitivity pneumonitis based on clinical features, bronchoalveolar lavage and transbronchial lung biopsy. By the double immunodiffusion test, precipitating lines between shimeji spore antigen and sera were observed in all of the patients. By enzyme-linked immunosorbent assay, the antibody activities against shimeji and three species of fungi (Cladosporium sphaerospermum, Penicillium frequentans, and Scopulariopsis species) were significantly higher in the sera of the patients than in those of normal subjects who were cultivating shimeji. Although it is not clear what causes this disease, these findings may be helpful in determining the specific antigen.

Role of free radicals in the pathogenesis of lipid-induced glomerulosclerosis in rats

BACKGROUND

We examined whether a high-cholesterol (HC) diet causes glomerulosclerosis in rats, and investigated the role of free radicals and lipid peroxidation in lipid-induced glomerulosclerosis.

METHODS

The rats were given a normal diet, a HC diet, or a HC diet with antioxidants and radical scavengers. Serum levels of lipid, lipid peroxide (LOOH), urinary excretion of protein (UP), and urinary norepinephrine excretion (UNE) were measured. The glomerular sclerosing score was used to evaluate the renal injury.

RESULTS

Blood pressure, total cholesterol, and LOOH were increased by a HC diet, as were UP and UNE. The HC diet induced renal injury. Treatment with superoxide dismutase, dimetylthiourea as a scavenger of hydroxyl radical (OH.), defferoxamine masilate as an iron chelator, or vitamin E inhibited the increases in blood pressure, LOOH, UP, and UNE, whereas total cholesterol was not affected. The production of superoxide anion (O2-.) by neutrophil and LOOH in the kidney was increased, and superoxide dismutase and hydrogen peroxide in the kidney were decreased. Almost all of these changes were attenuated by vitamin E; however, the O2-. production was not inhibited. OH. was increased by the HC diet, and it was normalized with the treatments. Furthermore, the sclerosing score was partially suppressed by the treatments. Ferric iron was stained in the proximal tubulus, and it was not observed in the treated rats.

CONCLUSIONS

The data suggest that lipid peroxidation is involved in the pathogenesis of lipid-induced glomerulosclerosis and that O2-. and OH. may play a role in the process.

Pressor hyperreactivity to mental and hand-grip stresses in patients with hypercholesterolemia

OBJECTIVE

To investigate the role of hypercholesterolemia in the regulation of blood pressure.

SUBJECTS AND METHODS

We compared blood pressure responses to arithmetic stress and hand-grip tests in normotensive patients with hypercholesterolemia n = 15) and a mean (+/- SEM) age of 49 +/- 3 years, and normal cholesterolemic controls (n = 22) aged 48 +/- 1 years. Blood pressure and heart rate were measured throughout the tests. We examined the intracellular Ca2+ concentration in platelets with or without low-density-lipoprotein stimulation (2.9 nmol/l, 10 mg/ml). The plasma nitrite plus nitrate and cyclic GMP were determined before and at the end of each test to evaluate nitric oxide production and activity.

RESULTS

Both tests showed that systolic/diastolic blood pressure was higher in the hypercholesterolemic patients than in the normal controls (stress test: 139 +/- 3/91 +/- 4 versus 127 +/- 2/80 +/- 3 mmHg, P < 0.01/P < 0.05; hand-grip test: 164 +/- 5/106 +/- 5 versus 144 +/- 3/88 +/- 3 mmHg, P < 0.01/P < 0.01). The intracellular Ca2+ concentration in platelets and the increase in response to low-density-lipoprotein stimulation were higher in the hypercholesterolemic patients (without stimulation: 72 +/- 3 versus 64 +/- 3 nmol/l, P < 0.01; with 2.9 nmol/l stimulation: 145 +/- 21 versus 89 +/- 6 nmol/l, P < 0.01). The increase in Ca2+ in response to 2.9 nmol/ml stimulation with low-density lipoprotein was positively related to the increase in mean blood pressure in response to the stress test (r = 0.56, P < 0.002). Nitric oxide production appeared to be increased in the hypercholesterolemic patients (65 +/- 5 versus 51 +/- 4 mmol/l, P < 0.05), and was not affected significantly by the tests. In contrast, cyclic GMP was lower in the patients and was increased significantly in the normal controls by the hand-grip test (P < 0.05). As a result, plasma cyclic GMP was lower in the patients (1.9 +/- 0.2 versus 2.5 +/- 0.1 nmol/l, P < 0.01). The ratio of plasma cyclic GMP to nitric oxide was also lower in the hypercholesterolemic patients at rest (P < 0.05), and at the end of the mental stress (P < 0.02) and hand-grip (P < 0.001) tests.

CONCLUSIONS

Patients with hypercholesterolemia showed an exaggerated blood pressure response to both mental stress and exercise, even if resting blood pressure was normal. Increases in the intracellular Ca2+ concentration can contribute to these excessive responses. A disproportionately lower level of cyclic GMP to nitric oxide in plasma may also be involved in these abnormal responses.

[Chronic hypersensitivity pneumonitis due to isocyanate in a patient presenting with acute symptoms 1 month after environmental exposure]

A 51-year-old man who had been working for 10 years with polyurethane paint containing isocyanate (MDI) was admitted to our hospital with complaints of fever and exertional dyspnea. Fine crackles were heard in both bases, and the patient had clubbed fingers. A chest X-ray film and computed tomograms of the lungs revealed patchy infiltrative shadows in both lung fields and subpleural honeycombing associated with irregular linear areas. Examination of bronchoalveolar lavage fluid showed increased T lymphocytes and a decreased CD 4/8 ratio. Specimens obtained by transbronchial lung biopsy revealed lymphoplasmacytic infiltration into the thickened alveolar walls, macrophage accumulation, and micro-epithelioid cell granulomas in the alveolar sacs. Hypersensitivity pneumonitis was suspected although the causative antigen was not identified because the results of short-term environmental provocation tests were negative in the patient's home and workplace. After discharge, the patient continued working as a paint sprayer. His acute symptoms recurred 1 month after exposure to isocyanate. Similar episodes occurred on two separate occasions. In addition, the patient tested positive for antibody to MDI-HSA in bronchoalveolar fluid. From the above observations, the patient was given a diagnosis of chronic hypersensitivity pneumonitis due to isocyanate (MDI). This condition is extremely rare. Furthermore, it is interesting that acute symptoms recurred 1 month after environmental exposure to the causative antigen.

[An elderly woman with chronic pigeon-breeder's disease]

A 64-year-old woman had been feeding more than 60 pigeons in a coop in her back yard for 35 years. Diffuse reticulonodular shadows were found on a chest radiograph obtained as part of an annual check-up eight years before admission to the hospital. She was given a tentative diagnosis of idiopathic pulmonary fibrosis and was observed. She was admitted to our hospital because she noticed dry coughing and shortness of breath. A chest CT scan revealed segmentally distributed honeycombing and bronchi-bronchioloectasis. Tests for IgA and IgG antibodies to extracts of pigeon droppings in serum samples and in samples of bronchoalveolar lavage fluid were strongly positive, as were tests for lymphocyte blastogenic responses to samples of pigeon serum Examination of lung-biopsy specimens obtained by video-assisted thoracoscopic surgery revealed bronchiolitis, alveolitis, and honeycombing in a centrilobular distribution. The patient was given a diagnosis of pigeon-breeder's disease. Chronic hypersensitivity pneumonitis without acute episodes might be misdiagnosed as idiopathic interstitial pneumonia or bronchiectasis, as happened in this case. The possibility of chronic hypersensitivity pneumonitis should be considered when patients are suspected to have pulmonary fibrosis. It is important to obtain the detailed information on past or current avian contact, working history, and the home environment.

Differential localization of s and e antigens in hepatitis B virus-associated glomerulonephritis

We report here a case of membranous glomerulonephritis associated with chronic hepatitis B (HB) virus infection and describe differential localization of HB antigens in glomeruli. The patient showed mild proteinuria and was positive for hepatitis B surface (HBs) antigen, hepatitis B envelope (HBe) antigen, and antibody to hepatitis B core (HBc) antigen in the serum. The antibody against hepatitis C was negative. A renal biopsy revealed membranous glomerulonephritis with mesangial proliferation. The immunohistochemical studies using monoclonal antibodies localized the HBe antigen along the capillary wall and the HBs antigen in the mesangial area. The immunoelectron microscopic study confirmed the localization of HB antigens: HBe antigen was located in the subepithelial and intramembranous electron dense deposits and HBs antigen in the mesangial deposits. Our present results provide the first report of the differential localization of HB antigens in glomeruli at both the light and electron microscopic levels. The differential localization of HB antigens will provide insight into the pathogenesis of membranous glomerulonephritis.

The threshold for thermoregulatory vasoconstriction during nitrous oxide/sevoflurane anesthesia is reduced in the elderly

Elderly patients become more hypothermic during surgery, shiver less postoperatively, and take longer to rewarm than younger patients. Similarly, the vasoconstriction threshold (triggering core temperature) is reduced approximately 1 degree C in elderly patients during nitrous oxide/isoflurane anesthesia. Accordingly, we tested the hypothesis that the vasoconstriction threshold in the elderly is also reduced approximately 1 degree C during nitrous oxide and sevoflurane anesthesia. Eleven young patients aged 30-50 yr and 14 elderly patients aged 60-80 yr were anesthetized with nitrous oxide (50%) and sevoflurane (1%). Mean skin temperature was calculated from four sites. Fingertip blood flow was estimated using forearm minus fingertip skin-temperature gradients, with a gradient of 0 degree C identifying onset of vasoconstriction. The distal esophageal temperature triggering onset of vasoconstriction identified the threshold for this thermoregulatory defense. The data from five patients who did not vasoconstrict at minimum core temperatures of 33-34 degrees C were eliminated, leaving 10 patients in each group. The vasoconstriction threshold was significantly less in the elderly (35.0 +/- 0.8 degrees C) than in younger patients (35.8 +/- 0.3 degrees C), despite similar mean skin temperatures (mean +/- SD, P < 0.01, Student's t-test). Age dependence of thermoregulatory vasoconstriction during nitrous oxide/sevoflurane anesthesia is similar to that previously observed during nitrous oxide/isoflurane anesthesia.

Vitamin E ameliorates the renal injury of Dahl salt-sensitive rats

Recently, hyperlipidemia as well as hypertension has been observed in Dahl salt-sensitive (S) rats. In this study, to investigate whether the lipid abnormality is involved in the renal injury of Dahl S rats, we examined the effect of vitamin E on glomerular sclerosis, as vitamin E is an inhibitor of lipid oxidation. Dahl S rats were given a high salt diet (8% NaCl) containing either normal vitamin E (2 mg/100 g) or high vitamin E (50 mg/100 g) for 4 weeks. Dahl salt-resistant (R) rats were given a high salt and normal vitamin E diet. The blood pressure in the Dahl rats increased and was not suppressed by the vitamin E supplement. Serum cholesterol and triglycerides in Dahl S rats were higher than in Dahl R rats at both 0 and 4 weeks. Vitamin E lowered the serum cholesterol level in Dahl S rats at 4 weeks (126 +/- 5 v 150 +/- 12 mg/dL, P < .01). Urinary protein excretion and serum creatinine increased in Dahl S rats, and vitamin E inhibited the increases significantly (urinary protein, 70.7 +/- 0.9 v 178.0 +/- 8.8 mg/day, P < .01; serum creatinine, 0.45 +/- 0.02 v 0.63 +/- 0.05 mg/dL, P < .01). Serum lipid peroxide (LPO) was higher in Dahl S rats than in Dahl R rats, and vitamin E lowered LPO in Dahl S rats (2.10 +/- 0.03 v 2.70 +/- 0.04 nmol/mL, P < .01). In the histologic study, sclerosing score (SS) of glomeruli, which represents the degree of glomerulosclerosis semiquantitatively, was higher in Dahl S rats than in Dahl R rats. Vitamin E lowered SS (114 +/- 3 v 157 +/- 6, P < .01) and ameliorated arterial injuries such as medial thickness with partial necrosis and severe fibrinoid proliferation with inflammatory cell infiltration. In all rats, SS was strongly correlated with urinary protein (r = 0.93, P < .01), serum cholesterol (r = 0.86, P < .01), and serum LPO (r = 0.89, P < .01). These results suggest that the renal injury in Dahl S rats is caused not only by hypertension but also by hyperlipidemia. Therefore, vitamin E might ameliorate the renal damage by inhibiting the oxidation of lipids.

Relation of 24-h ambulatory blood pressure with plasma potassium in essential hypertension

The established associations between blood pressure (BP) and electrolytes are mostly based on either dietary intake or urinary excretion data. We measured office BP, ambulatory BP (ABP) using the automated oscillometric ABPM-630 device, and plasma electrolytes in 82 essential hypertensive patients to examine the relation between BP and plasma electrolytes. Significant negative correlations were observed between plasma potassium concentration and 24-h systolic BP (r = -0.336) and diastolic BP (r = -0.298) in our patients. Plasma potassium concentration inversely correlated also with both daytime and nighttime systolic and diastolic BPs. There was no relation between office BP and plasma potassium concentration. These findings indicate that in essential hypertensives plasma potassium concentration is inversely related to ABP including daytime and nighttime BPs and suggest that potassium may be a factor determining the whole day BP in essential hypertension.

Recurrent histiocytic necrotizing lymphadenitis (Kikuchi's disease) in an human T lymphotropic virus type I carrier

We describe a case of recurrent histiocytic necrotizing lymphadenitis (HNL) with aseptic meningitis. The patient was a 46-year-old male and a carrier of human T lymphotropic virus type I (HTLV-I). The patient had a past medical history of at least three relapses of HNL. In addition, his sister, who was also an HTLV-I carrier, had recurrent clinical episodes consistent with those of HNL, suggesting familial HNL occurrence. This observation suggests the possibility that HTLV-I infection is relevant to the pathogenesis of HNL.

Ouabainlike compound in hypertension associated with ectopic corticotropin syndrome

Molecular mechanisms related to sodium retention have been implicated in the pathogenesis of hypertension. It is unclear how sodium retention leads to a rise in blood pressure, but ouabainlike compound may act as a final common pathway in sodium-induced hypertension. In ectopic corticotropin syndrome, hypertension has been attributed to cortisol inactivation overload, giving rise to mineralocorticoid-type hypertension. We sequentially measured plasma and urinary levels of ouabainlike compound over 2 months to evaluate its role in the hypertensive mechanisms in a 64-year-old man with this syndrome caused by lung cancer. His data included hypokalemia and increased cortisol concentrations, corticotropin levels, and urinary 17-hydroxycorticosteroid excretion. Plasma renin activity was suppressed. Plasma and urinary levels of ouabainlike compound were markedly increased concomitantly with high blood pressure. The maximum plasma level was 40-fold the normal range of the subject. After chemotherapy, ouabainlike compound levels gradually decreased in parallel with the decline in blood pressure and rise in potassium concentration. A correlation was observed between plasma and urinary levels of ouabainlike compound (P < .05). Plasma and urinary levels of ouabainlike compound correlated with systolic (P < .01) and diastolic (P < .05) pressures, respectively. The peak of ouabainlike compound in plasma and urine coincided with that of authentic ouabain on high-performance liquid chromatography. Ouabainlike compound derived from urine inhibited [3H]ouabain binding to human erythrocytes. These findings suggest that ouabainlike compound with biological activity could partly account for hypertension in ectopic corticotropin syndrome.

[Sevoflurane comparably decreases the threshold for thermoregulatory vasoconstriction as isoflurane]

The core temperature triggering thermoregulatory arteriovenous shunt constriction is defined as the threshold for vasoconstriction. Vasoconstriction helps prevent further core hypothermia by decreasing cutaneous heat loss and constraining metabolic heat to the core thermal compartment. A previous study showed isoflurane inhibited thermoregulatory threshold. However there is no study to confirm whether sevoflurane perturb thermoregulatory vasoconstriction or not. Consequently we tested the hypothesis that 1.0 minimum alveolar concentration (MAC) sevoflurane and 1.0 MAC isoflurane would reduce the vasoconstriction threshold comparably. With institutional review board approval, we studied 20 patients, aged 20-60 yr, undergoing open abdominal surgery. No premedication was given. Ten patients each were anesthetized with 1.0 MAC sevoflurane (2.0%) alone or 1.0 MAC isoflurane (1.2%) alone. A forearm minus fingertip, skin temperature gradient 0 degree C was considered to demonstrate significant vasoconstriction; the esophageal temperature triggering vasoconstriction identified the threshold. Morphometric characteristics were comparable in each group. The threshold for vasoconstriction was 35.1 +/- 0.4 degrees C in the patients given 1.0 MAC sevoflurane, which was comparable that in those given 1.0 MAC isoflurane: 35.3 +/- 0.7 degrees C. We thus conclude that sevoflurane impairs thermoregulation comparably with isoflurane.

Nitrous oxide decreases the threshold for vasoconstriction less than sevoflurane or isoflurane

The core temperature triggering thermoregulatory arteriovenous shunt constriction is designated the threshold for vasoconstriction. High thresholds are generally desirable because vasoconstriction helps prevent further core hypothermia by decreasing cutaneous heat loss and constraining metabolic heat to the core thermal compartment. Previous studies suggest that nitrous oxide (N2O) may inhibit thermoregulatory vasoconstriction less than comparable doses of volatile anesthetics. To confirm this impression, we tested the hypothesis that 0.5 minimum alveolar anesthetic concentration (MAC) N2O combined with 0.5 MAC sevoflurane or isoflurane would reduce the vasoconstriction threshold less than 1.0 MAC sevoflurane or isoflurane. With institutional review board approval, we studied 40 patients, aged 20-60 yr, undergoing open abdominal surgery. No premedication was given. Ten patients each were anesthetized with: 1) N2O (50%) and 0.5 MAC sevoflurane (1%); 2) sevoflurane alone (2%); 3) N2O (60%) and 0.5 MAC isoflurane (0.6%); and, 4) isoflurane alone (1.2%). A forearm minus fingertip, skin temperature gradient > or = 0 degree C was considered significant vasoconstriction; the esophageal temperature triggering vasoconstriction identified the threshold. Morphometric characteristics were comparable in each group. The threshold for vasoconstriction was 35.8 +/- 0.3 degrees C in the patients given 50% N2O combined with 0.5 MAC sevoflurane, which was significantly greater than that in those given 1.0 MAC sevoflurane: 35.1 +/- 0.4 degrees C. Similarly, the threshold for vasoconstriction was 35.9 +/- 0.3 degrees C in the patients given 60% N2O combined with 0.5 MAC isoflurane, which was significantly greater than that in those given 1.0 MAC isoflurane: 35.0 +/- 0.5 degrees C. We thus conclude that N2O impairs thermoregulation less than sevoflurane or isoflurane.

[A case of thymic carcinoma successfully controlled by combined chemotherapy and irradiation]

There is no well established therapeutic protocol for advanced thymic carcinoma, although chemotherapy and irradiation can apparently be used to control the malignancy. Here we report a case of advanced thymic carcinoma successfully controlled by combination of treatment with systemic chemotherapy and irradiation. A 79-year-old man was admitted to the Hiratsuka Kyosai Hospital with complaints of productive cough and dyspnea. Chest roentgenogram and computerized tomography on admission revealed a tumorous lesion in the anterior mediastinum and on accumulation of left pleural and pericardial effusion fluid. The tumor was diagnosed as a thymic squamous cell carcinoma, after percutaneous needle biopsy. Because of extension to the left pleura and cardiac sac, the tumor was considered to be unresectable and systemic chemotherapy (CDDP + VDS + MMC) was begun. After drainage of the pericardial effusion fluid, intrapericardial injection of MMC was also done. The anterior mediastinum was irradiated. The patient has been doing well, with regression of the thymic tumor for 48 months after irradiation. This case provides important information that can be used to establish an effective therapeutic regimen for advanced thymic carcinoma.

Adamantinoma of the rib metastasizing to the liver

Adamantinoma is a rare bone tumor, most of which originates in the long bone. Here, we present a case of adamantinoma of the rib with liver metastasis. The patient, a 69-year-old man, complained of dull chest pain for over 6 months. Chest X-ray and CT film revealed osteolytic mass of the right 7th rib. Under the clinical diagnosis of hepatic tumor with rib metastasis, resection of the rib and partial hepatectomy were performed. Pathologically, the bone tumor was diagnosed as primary adamantinoma and the liver tumor was its metastasis. The patient has been well without adjuvant chemotherapy for 5 years after the operation.

[Comparison between diltiazem and nicardipine used during anesthesia for coronary revascularization]

The effects of diltiazem (0.1 mg.kg-1 + 3 micrograms.kg-1.min-1) and nicardipine (0.01 mg.kg-1 + 2 micrograms.kg-1.min-1) on circulatory parameters were compared in 30 patients with ischemic heart disease, who underwent coronary revascularization. These drugs were administered intravenously via a Swan-Ganz catheter after induction of fentanyl anesthesia. The group injected with diltiazem showed significant decreases in heart rate, mean arterial pressure, cardiac output, left ventricular stroke work and rate-pressure product. The group injected with nicardipine showed significant decreases in mean arterial pressure, systemic vascular resistance, rate-pressure product and pressure-rate quotient. There were significant differences between the two groups in cardiac output, stroke volume, systemic vascular resistance and left ventricular stroke work. The results suggest that diltiazem protects the ischemic heart by slight cardiac suppression and that nicardipine reduces afterload by marked vascular dilatation during anesthesia for coronary revascularization. Both Ca-channel blockers were demonstrated to be useful.

Senegoses J-O, oligosaccharide multi-esters from the roots of Polygala senega L

From the roots of Polygala senega L. six new oligosaccharides, called senegoses J-O, were isolated and their structures were elucidated by spectroscopic and chemical means. These oligosaccharides were esterified with acetic, benzoic, p-coumaric and ferulic acids.

A biphasic effect of noradrenaline on renin release from rat juxtaglomerular cells in vitro is mediated by alpha 1- and beta-adrenoceptors

The direct effect of noradrenaline on renin release from juxtaglomerular (JG) cells in vitro were investigated in a dynamic superfusion system of dispersed rat renal cortical cells. At low concentrations (1-100 nmol/l), noradrenaline stimulated renin release in a dose-dependent manner, while at higher concentrations (0.1-1 mmol/l) it inhibited renin release. The stimulatory effect of 0.1 mumol noradrenaline/l was completely blocked by a beta-adrenoceptor antagonist, propranolol (0.1 mumol/l). When applied at concentrations of 1 mumol/l or 10 mumol/l, noradrenaline had no consistent effect on renin release, although 10 mumol noradrenaline/l had an inhibitory effect in the presence of propranolol (0.1 mumol/l). The inhibitory effect of noradrenaline (0.1 mmol/l) was converted to a stimulatory effect by the addition of an alpha 1-adrenoceptor antagonist (bunazosin, 1 mumol/l), but was not altered by the addition of an alpha 2-adrenoceptor antagonist (yohimbine, 1 mumol/l). These results indicate that low concentrations of noradrenaline directly stimulate renin release from JG cells by the activation of beta-adrenoceptors, while high concentrations of noradrenaline inhibit renin release by the activation of alpha 1-adrenoceptors. Accordingly, a dynamic balance may exist between beta-adrenergic stimulation and alpha 1-adrenergic depression of renin release.

[Clinical study on the priming principle of muscle relaxants: comparison of pancuronium with vecuronium]

The priming principle of non-depolarizing muscle relaxants was treated in this study. The subjects were 48 patients. We administered divided doses (p) and single dose (s) using pancuronium (P) and vecuronium (V), and compared the 4 groups (Pp, Ps, Vp, Vs). Pp and Vp groups received intravenous injection of 0.02 mg.kg-1 first, and 0.08 mg.kg-1 after 5 minutes. Ps and Vs groups received intravenous injection of 0.1 mg.kg-1. Relaxograph was used for monitoring muscle relaxation. First-twitch (T1) and train-of-four ratio (TR) were recorded, and the time intervals required to decrease T1 to 25% (T1-25) and 5% (T1-5) were determined. T1-25 (sec) was 126.2, 153.1, 82.7, and 132.7 in Pp, Ps, Vp, and Vs group, respectively; and T1-5 (sec) was 192.8, 229.8, 112.7, and 165.2 in Pp, Ps, Vp, and Vs group, respectively. As these values suggest, there were no significant differences between Pp and Ps group, while significant differences were noted between Vp and Vs group. The following conclusions were obtained. Clinical usefulness of the priming principle was not shown with pancuronium, but was noted with vecuronium. However, the action of vecuronium appeared rapidly after single dose, and some patients complained of dyspnea during priming. Consequently, the priming principle was not considered to be clinically beneficial.

Plasma renin activity and norepinephrine as predictors for antihypertensive effects of nifedipine and captopril

To examine predictors for the efficacy of antihypertensive agents, we investigated the effects of nifedipine and captopril on blood pressure (BP) and humoral factors in patients with essential hypertension. Eleven essential hypertensive patients (mean age: 54) were treated with long acting nifedipine at 20 to 40 mg/day for 8 weeks and 25 essential hypertensives (mean age: 51) were treated with captopril at 37.5 to 75 mg/day. Blood pressure was measured every 2 weeks. Plasma renin activity (PRA), and plasma concentrations of aldosterone, epinephrine and norepinephrine were determined before and at the end of treatment. Both nifedipine and captopril decreased BP (nifedipine: mean BP 119 +/- 3 to 101 +/- 2 mm Hg, captopril: 124 +/- 2 to 100 +/- 2, P less than .01 for each), whereas neither of them affected heart rate. The 8-week treatment of nifedipine showed no significant effect on humoral factors. Captopril increased PRA by 63% (P less than .05) and decreased plasma epinephrine by 42% (P less than .01) and norepinephrine by 35% (P less than .01). The change in mean BP was positively correlated with pretreatment PRA (r = 0.68, P less than .01) in nifedipine-treated patients and inversely with pretreatment norepinephrine (r = -0.53, P less than .01) in captopril treatment. The results suggest that both nifedipine and captopril were effective antihypertensive agents and that the long term treatment of nifedipine is more effective in essential hypertensives with lower PRA, while captopril is more effective in those with higher plasma norepinephrine concentration.

Immunohistochemical study of vascular lesions in severe hypertension induced by DOCA and salt administration to spontaneously hypertensive rats

In order to evaluate whether immunoglobulin deposition in vessels plays some role in the development of vascular lesions in severe hypertension, an immunohistochemical study was performed in spontaneously hypertensive rats (SHRs), to which deoxycorticosterone acetate (DOCA) and salt were administered. DOCA and salt rapidly induced severe hypertensive vascular lesions, including necrotizing arteriolitis and productive endarteritis. In these rats, considerable deposits of IgG and IgM were found in the small arteries and arterioles of the kidneys. These deposits were accompanied by complement (C3), and could be eluted by acid incubation. They were localized in periodic acid-Schiff-positive insudative lesions, which were thought to be an early phase of the hypertensive vascular lesions. These results suggest that the immunoglobulins might be bound to an unknown antigen in the vascular lesions and that some immunological mechanism mediated by the immunoglobulins is involved in the development of vascular lesions in severe hypertension.

Role of adenosine A1 and A2 receptors in the regulation of aldosterone production in rat adrenal glands

To investigate the roles of adenosine A1 and A2 receptors in the regulation of aldosterone production, we examined the effects of adenosine and adenosine agonists (N6-cyclohexyl adenosine; selective adenosine A1 receptor agonist and 5'-N-ethylcarboxamine adenosine; selective adenosine A2 receptor agonist) on aldosterone and cyclic AMP production in rat adrenal capsular cells. Neither adenosine nor 5'-N-ethylcarboxamine adenosine caused significant effects on basal aldosterone or cyclic AMP production. Also, adenosine (10(-3) M) showed no consistent effects on aldosterone and cyclic AMP production induced by ACTH. On the other hand, N6-cyclohexyl adenosine exhibited a significant inhibition of basal aldosterone and cyclic AMP production at doses of 10(-4) M and 10(-3) M; furthermore, 10(-3) M N6-cyclohexyl adenosine inhibited aldosterone and cyclic AMP production stimulated by ACTH. These results suggest that adenosine A1 receptors are coupled to and inhibit adenylate cyclase and may be involved in the inhibition of aldosterone production.

Effects of magnesium on changes in blood pressure and plasma aldosterone induced by angiotensin II

This study examined the effects of magnesium on changes in blood pressure and plasma aldosterone concentration (PAC) elicited by angiotensin II in rats. The infusion of angiotensin II (0.1 nmol/kg/min) for 30 min increased mean arterial pressure (MAP) and PAC. Simultaneous infusion of magnesium sulphate (5 mumols/kg/min) attenuated the MAP elevation (157.0 +/- 5.2 (SE) v 141.6 +/- 3.5 mm Hg, P less than .01) and the increase in PAC (447 +/- 70 v 233 +/- 50 pg/mL, P less than .01) brought about by angiotensin II. These effects of magnesium were abolished when endogenous angiotensin II was suppressed by the administration of captopril, an angiotensin converting enzyme inhibitor. The results suggest that magensium may attenuate the biological actions of angiotensin II.

The extrarenal effects of atrial natriuretic peptide on body fluid distribution

To study the effects of atrial natriuretic peptide (ANP) on body fluid volume regulation, we estimated the changes in intra- and extravascular fluid volume by measuring hematocrit (Hct), plasma protein concentration and water balance, and the changes in intra- and extracellular fluid volume by the electrical impedance method during intravenous infusion of ANP. We did two studies, as follows: ANP was infused into 18 patients with essential hypertension, 29 with renal parenchymal hypertension and 15 normotensives at 0.025 microgram/kg/min for 40 min. Both hypertensive groups showed greater natriuretic responses to ANP than normotensives. ANP infusion into essential hypertensive patients increased the urinary excretion of water by 125%, Na by 205%, Hct by 4.2% and plasma total protein (TP) by 5.2% (each P less than .001). In 9 patients (1 with renal hypertension and 8 normotensives) who did not show a natriuretic response (-2.1%), the infusion of ANP also significantly increased Hct (3.8%) and plasma TP (3.1%, each P less than .01). The electrical impedance method was applied to 12 subjects to simultaneously detect the intracellular (Ri) and extracellular resistivities (Re), of which reciprocals reflect the fluid volume in the extra- and intracellular spaces, respectively. ANP infusion increased Re in all subjects (3.96 +/- 0.16 [SE] v 4.03 +/- 0.16 omega.m, P less than .05), but decreased Ri in 7. Changes in urinary Na excretion correlated positively with those in both Re (r = 0.62, P less than .05) and Ri (r = 0.75, P less than .01).(ABSTRACT TRUNCATED AT 250 WORDS)

Effects of treatment with captopril on exercise tolerance and plasma catecholamines in elderly hypertensives

We examined the effects of antihypertensive therapy with captopril, an angiotensin converting enzyme inhibitor, on exercise tolerance and humoral factors in 19 elderly patients (greater than 60 years old) with essential hypertension. Captopril (37.5-75 mg/day) was administered for 8 weeks. Fourteen of the 19 patients in whom captopril was effective took a treadmill exercise test according to Kattus' protocol. Exercise tolerance was increased in all patients (from 13.1 +/- 1.3 to 16.5 +/- 1.0 min, P less than 0.01). Captopril attenuated the rise in blood pressure during the exercise test but did not affect the heart rate. Resting values of plasma adrenaline decreased by 47% and noradrenaline by 17%, with no significant changes in plasma renin activity (PRA) or aldosterone. The change in mean blood pressure showed an inverse relationship to pretreatment plasma noradrenaline (r = -0.73, P less than 0.01). The results show that captopril is effective in the treatment of hypertensive elderly patients, and suggest that the sympathetic nervous system is involved in the mechanism of the antihypertensive response to captopril therapy.

Magnesium ion: a possible physiological regulator of aldosterone production

We examined the direct effect of magnesium ion on aldosterone production by adrenal cells using collagenase-dispersed zona-glomerulosa cells in rats. The effects of magnesium on aldosterone production stimulated by angiotensin II or ACTH were also investigated. Both magnesium sulphate (MgSO4) and magnesium chloride (MgCl2) (0 to 2 mM) decreased aldosterone production in a dose-dependent manner. In comparison with magnesium-free medium, 2 mM MgSO4 inhibited aldosterone production by 73% and MgCl2 by 65%. In addition, MgSO4 showed an inhibitory effect on aldosterone production stimulated by angiotensin II (10pM to 10nM), whereas it had no significant effect on aldosterone production due to ACTH stimulation (10pM to 10nM). These data suggest that magnesium has an inhibitory action on aldosterone production in vitro and may be a physiological regulator of aldosterone production.

Endothelin: a new inhibitor of renin release

Endothelin is a recently-discovered vasoconstrictor peptide which is produced by endothelium and acts on vascular smooth muscle cells. At present its actions on other organs or cells are unknown. We studied the effect of endothelin on renin release in a dynamic superfusion system of dispersed rat juxtaglomerular (JG) cells. Endothelin in concentrations of 10(-11) M or more inhibited renin release dose-dependently and this inhibitory action vanished in the absence of extracellular Ca. It is suggested that endothelin is an inhibitory regulator of renin secretion from JG cells and its action is Ca-dependent.

Dopamine and aldosterone in adrenal glomerulosa cells in spontaneously hypertensive rats

To investigate the possible significance of dopamine in aldosterone production, the adrenal zona glomerulosa was examined for the presence of dopamine and aldosterone in spontaneously hypertensive rats (SHR) and Wistar-Kyoto rats (WKY) aged 10 weeks. Aldosterone and dopamine were measured in the adrenal capsular portions (mostly zona glomerulosa) by radio-immunoassay and high-performance liquid chromatography, respectively. Dopamine was found in the adrenal zona glomerulosa, with a significantly higher level in SHR than in WKY, whereas the content of aldosterone was significantly lower in SHR than in WKY. Furthermore, there was a significant negative relationship between the content of dopamine and that of aldosterone. These results suggest that the inhibitory effect of dopamine on aldosterone production may be mediated within the adrenal zona glomerulosa and that an increased dopamine content in the adrenal zona glomerulosa may contribute to the decreased aldosterone content in SHR.

The effect of atrial natriuretic peptide on acid-base balance in rats with chronic renal failure

We explored the effects of 12-hour infusion of atrial natriuretic peptide (alpha-rANP:rat, 1-28) on arterial acid-base balance, using 5/6 nephrectomized rats with chronic renal failure. Before the infusion, nephrectomized rats had a higher mean arterial blood pressure, greater urine volume, and lower creatinine clearance than the normal controls, but they did not show a significant difference in arterial hydrogen ion concentration (pH), plasma bicarbonate concentration (HCO3-), partial pressure of carbon dioxide (PCO2), plasma base excess (BE), or plasma ANP concentration. alpha-rANP infusion produced a continuous blood pressure reduction in both nephrectomized and control rats. Urine volume and urinary sodium and potassium excretion tended to increase at 2-hour infusion, but not at 12-hour infusion. In the controls alpha-rANP significantly increased pH from 7.47 to 7.50, and decreased PCO2 by 14%. In contrast, in nephrectomized rats alpha-rANP significantly decreased pH from 7.48 to 7.44, HCO3- by 13%, and BE from -0.07 to -3.22 meq/l. Rats with chronic renal failure had greater reduction in HCO3- than the controls (p less than 0.05). There was no difference in plasma ANP level between the two groups. Thus, it is indicated that the long-term infusion of alpha-rANP reduces pH in rats with chronic renal failure, thereby adversely affecting the acid-base balance.

Effects of intracerebroventricular infusion of aldosterone on blood pressure and sodium and potassium concentrations in cerebral spinal fluid in rats

The central effects of aldosterone on blood pressure and sodium (Na) and potassium (K) concentrations in cerebral spinal fluid (CSF) were examined by chronic intracerebroventricular (ICV) infusion of aldosterone. The rats were infused for 14 days with either ICV artificial CSF, ICV aldosterone or aldosterone subcutaneously using miniosmotic pumps. ICV aldosterone increased blood pressure and lowered the K concentration in CSF. The Na concentration in CSF tended to increase, although not significantly. No significant changes in concentrations of serum Na and K, plasma renin, aldosterone, norepinephrine or ANP were observed. These results suggest that aldosterone induces blood pressure elevation through a central action, and that a change in Na or K concentration in CSF may be involved.

Evidence for lack of a role of cGMP in effect of alpha-hANP on aldosterone inhibition

To investigate the role of guanosine 3',5'-cyclic monophosphate (cGMP) in the inhibitory effect on aldosterone production of alpha-human atrial natriuretic polypeptide (alpha-hANP) we first compared the effects of the peptide with those of sodium nitroprusside (SNP) on the production of aldosterone and cGMP in dispersed adrenal capsular cells of rats, second, examined the effects of derivatives of cGMP on the production of aldosterone, and, third, studied the influence of potassium on the effects of alpha-hANP on the production of aldosterone and cGMP. alpha-hANP at concentrations of 3 X 10(-8) to 3 X 10(-7) M decreased the production of aldosterone in a dose-dependent manner, while markedly increasing the production of cGMP. On the other hand, although SNP at concentrations of 10(-5) to 10(-3) M increased the production of cGMP in a dose-dependent manner, it caused no significant changes in the production of aldosterone. Neither dibutyryl cGMP nor 8-bromo-cGMP affected the production of aldosterone in the adrenal cells. Although the aldosterone-inhibitory effect of alpha-hANP was lost in the potassium-free medium, the cGMP-stimulatory effect of the peptide was not altered by adding potassium to the incubation medium at concentrations of 0-5 meq/l. These results suggest that cGMP plays a minor role in the inhibitory effect of alpha-hANP on the production of aldosterone and that the production of cGMP stimulated by the peptide is not directly involved in the decrease in aldosterone production in adrenal capsular cells of rats.

Relationship between the renin-aldosterone system and atrial natriuretic polypeptide in rats

In order to examine the relationship between the renin-aldosterone system and atrial natriuretic polypeptide (ANP), we investigated the effects of alpha-human atrial natriuretic polypeptide (alpha-hANP) on the plasma concentrations of renin (PRC) and aldosterone (PAC), as well as the effects of captopril pretreatment on the natriuresis and blood pressure reduction induced by alpha-hANP in rats. Although alpha-hANP infused into conscious rats at 0.67 microgram min-1 kg-1 markedly increased the urinary excretion of sodium and decreased mean arterial pressure, its infusion did not change PRC; however, it significantly lowered PAC. Frusemide infusion at 20.8 micrograms min-1 kg-1 induced natriuresis comparable with that of alpha-hANP and it elevated both PRC and PAC, but mean arterial pressure was not altered. Pretreatment of rats with captopril did not have any significant influence on the acute natriuretic and hypotensive effects of alpha-hANP. Although the inhibitory effect of ANP on the renin-aldosterone system may be involved in the chronic modulation of body fluid volume and blood pressure, this effect does not seem to be directly involved in the acute natriuretic and hypotensive effects of the peptide.

Blood pressure, renal and endocrine responses to alpha-human atrial natriuretic polypeptide in healthy volunteers

Intravenous infusion of graded doses of alpha-human atrial natriuretic polypeptide (alpha-hANP) resulted in a dose-dependent decrease in blood pressure and an increase in heart rate in 11 healthy male volunteers. However, there were no significant changes in urine output or in the urinary excretion rate of sodium. Glomerular filtration rate did not change, while renal blood flow decreased, leading to significant increases in filtration fraction and renal vascular resistance. Although plasma renin activity (PRA) and plasma concentration of norepinephrine (PNE) increased during infusion of alpha-hANP (both p less than 0.001), plasma concentrations of aldosterone (PA) and cortisol (PC) decreased (both p less than 0.001). Plasma concentration of arginine vasopressin (PAVP) did not change during the infusion, but greatly increased after cessation of the infusion. The hematocrit increased slightly, but significantly, during the infusion. These results show that, although alpha-hANP has a potent hypotensive action and inhibits the secretion of aldosterone, cortisol, and probably arginine vasopressin, it does not dilate renal vessels in normotensive persons, and likely increases vascular permeability. The lack of consistent diuretic and natriuretic responses to alpha-hANP may be related to the predominance of the hypotensive effect over the renal effects of the peptide in normotensive persons, or a diurnal change may have served to obscure such a response.