Inhibition of aldosterone production by an atrial extract

Crude extracts of rat atria reduced the basal amount of aldosterone released from rat zona glomerulosa cells and partially inhibited aldosterone stimulation by adrenocorticotropic hormone and angiotensin II. The destruction of this activity by trypsin suggests that the active factor is a peptide, possibly atrial natriuretic factor. These data suggest that atrial natriuretic factor affects sodium excretion by the kidneys both directly and through the inhibition of aldosterone production.

Effect of atrial peptides on aldosterone production

This study examines the effects of the synthetic atrial peptides (atriopeptin I, II, and III) on aldosterone and corticosterone production by rat adrenal cell suspensions. Furthermore, we studied the effect of atriopeptin II infusion on the plasma aldosterone response to angiotensin II in the rat in vivo. Atriopeptin I, II, and III decreased aldosterone release from zona glomerulosa cells in a dose-dependent fashion. 10 pM atriopeptin II inhibited basal aldosterone release significantly (P less than 0.01), and 10 nM atriopeptin II or III lowered it by 79%. Atriopeptin II decreased the sensitivity of the glomerulosa cells to adrenocorticotropic hormone (ACTH) and angiotensin II. Atriopeptin II had no effect on basal or ACTH-stimulated corticosterone release by fasciculata-medullary cells. In vivo infusions of angiotensin II with or without simultaneous infusions of atriopeptin II showed that atriopeptin II significantly inhibited the aldosterone response to angiotensin II. This inhibition by atriopeptin II was independent of any effect on plasma renin activity, serum potassium, or ACTH. These data raise the possibility that the atrial natriuretic peptides may affect sodium excretion by the kidney, not only directly, but also indirectly through the inhibition of aldosterone production.

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.

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.

Elevated plasma catecholamines in hypertensives with primary glomerular diseases

Supine plasma concentration of norepinephrine (PNE), epinephrine (PE), and aldosterone (PA), plasma renin activity (PRA), and blood volume (BV) were measured in 25 normotensive and 11 hypertensive patients with biopsy-proven glomerulonephritis who had serum creatinine concentrations of less than 1.6 mg/dl, and in 20 normotensive control subjects. PNE and PE were measured according to the trihydroxyindol method using high pressure liquid chromatography. Renal clearances of p-aminohippurate (CPAH) and endogenous creatinine (Ccr) were also determined. Age, BV, and 24-hour urinary excretion of sodium were not significantly different in the three groups. Although all the measured variables were comparable between the control subjects and the normotensive nephritic patients, blood pressure, PNE, PE, PRA, and PA were significantly higher and CPAH and Ccr were significantly lower in the hypertensive nephritic patients than in the normotensive nephritic patients or the control subjects. In the pooled nephritic patients, mean blood pressure was significantly correlated with PNE (r = 0.76, p less than 0.001), PE (r = 0.34, p less than 0.05), PRA (r = 0.33, p less than 0.05), PA (r = 0.40, p less than 0.05) and CPAH (r = -0.51, p less than 0.01). Highly significant positive correlation was also observed between PNE and systolic pressure (r = 0.63, p less than 0.001) or diastolic blood pressure (r = 0.78, p less than 0.001). The results suggest that deterioration of renal function is an important factor in the development of hypertension even in non-azotemic patients with glomerulonephritis, and that increased activities of the sympathetic nervous system and the renin-aldosterone system participate, in part, in elevating blood pressure in the hypertensive nephritic patients. Mechanisms involved in the elevation of plasma concentrations of catecholamines and renal effects on the plasma catecholamines remain to be elucidated.

Effect of changes in sodium or potassium balance, and nephrectomy, on adrenal renin and aldosterone concentrations

An active form of renin was confirmed in the adrenal gland of rats. It had a molecular weight of 40,000, generated angiotensin I (AI) from natural renin substrate at pH 7.4, and was found at concentrations 30 to 60 times higher than plasma renin in rats on a normal diet. Changes in sodium diet induced changes in adrenal capsular renin concentration (high Na 2.21 +/- 0.34, normal Na 4.34 +/- 0.53, low Na 13.19 +/- 1.67 ng AI/mg protein/hr). A high potassium diet also increased adrenal capsular renin from 5.27 +/- 0.53 to 39.78 +/- 5.68 ng AI/mg protein/hr, while plasma renin concentration decreased from 7.28 +/- 0.63 in the normal diet to 5.05 +/- 0.60 on the high potassium diet. Neither diet altered the concentration of renin in the fasciculata-medullary portion of the adrenal gland. Nephrectomy markedly increased the renin concentration in the adrenal capsules without any effect on the decapsular cells (20 hours after nephrectomy, 71.5 +/- 10.6 ng AI/mg protein/hr). Sodium loading or dexamethasone treatment prior to nephrectomy blunted the rise in adrenal renin (nephrectomy + dexamethasone = 27.64 +/- 4.33 ng AI/mg protein/hr; nephrectomy + NaCl = 38.70 +/- 5.82 ng AI/mg protein/hr). In all experiments, there was a positive correlation between adrenal renin and adrenal aldosterone concentrations, but the experiments did not rule out the possibility that this positive correlation was due to two independent variables changing in the same direction and not causally related. In conclusion, adrenal renin may be a local hormone, involved in the regulation of aldosterone production.

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.

Adrenal renin: a possible regulator of aldosterone production

We have confirmed the presence of adrenal renin and have shown that the concentration is much higher in the glomerulosa cells. The renin concentration of these cells is influenced by changes in sodium balance and after nephrectomy, while the renin of the fasciculata-medullary tissue is not. There is a positive correlation between adrenal renin and aldosterone concentration. The data suggest that adrenal renin may be a local hormone that plays a role in the regulation of aldosterone production.

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.

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.

Plasma levels of 6-keto-prostaglandin F1 alpha in normotensive subjects and patients with essential hypertension

To assess the pathophysiological role of prostacyclin in essential hypertension, plasma levels of 6-keto-prostaglandin F1 alpha (6-keto-PGF1 alpha), a stable, nonenzymatic metabolite of prostacyclin, were assayed in 25 patients with essential hypertension and 25 age-matched normotensive subjects. Supine plasma levels of 6-keto-PGF1 alpha were 270 +/- 14 (SE) in normotensive subjects and 203 +/- 14 pg/ml in the patients with essential hypertension. The difference was statistically significant (p less than 0.001). There was a significant negative correlation between plasma levels of 6-keto-PGF1 alpha and systolic blood pressure (r = 0.44, P less than 0.002), diastolic blood pressure (r = 0.55, p less than 0.001), or mean blood pressure (r = 0.56, p less than 0.001) in the pooled subjects. The same relationship was found in the hypertensive patients. There was no definite relationship either between plasma levels of 6-keto-PGF1 alpha and plasma renin activity (PRA) in the supine position, or between changes in plasma levels of 6-keto-PGF1 alpha and changes in PRA after 60 min of upright posture. These results indicate that circulating prostacyclin is reduced in patients with essential hypertension as compared to normotensive subjects. This reduction of plasma prostacyclin may participate, in part, in the maintenance of blood pressure elevation in patients with essential hypertension. It is also suggested that upright posture is not sufficient to elevate circulating prostacyclin.

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.

Role of the aldosterone system in the salt-sensitivity of patients with benign essential hypertension

This study compared responses of blood pressure, plasma concentrations of norepinephrine (PNE) and aldosterone (PA), plasma renin activity (PRA) and urinary excretion of aldosterone during a 5-day period of high salt intake in 11 untreated patients with essential hypertension and 11 age-matched normotensive control subjects. The hypertensive patients all had blood pressures that had been above 160 systolic and/or 90 mmHg diastolic before admission and had decreased to below 150/90 mmHg with only bed-rest and mild salt restriction (6 Gm per day). Sodium balance was also measured before and after high salt intake (16 Gm per day). The hypertensive patients showed both a significant reduction in blood pressure after hospitalization and a significant blood pressure elevation when salt intake was increased. In contrast, no obvious changes in blood pressure were observed in the normotensive subjects. Sodium retention and decreases in PNE and PRA during the high salt period were similar in both groups. However, the reduction in PA and urinary aldosterone excretion in response to excessive salt intake was less pronounced in the hypertensive patients than in the normotensive subjects. The ratio of percentage changes in PA to percentage changes in PRA after salt loading was significantly lower in the hypertensive patients than in the normotensive subjects. In addition, the changes in PA during salt loading were inversely proportional to changes in blood pressure (r = 0.66, p less than 0.01). Thus, it is suggested that the sensitivity of blood pressure to increased dietary salt intake in hypertensive patients may be related to altered aldosterone dynamics, and that the blunt responses of the PA and urinary excretion of aldosterone can be attributed to reduced sensitivity of the adrenal cortex to changes in circulating angiotensin.

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.

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.

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.

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.

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.

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.

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.

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.

Effects of allopurinol, a xanthine oxidase inhibitor, on renal injury in hypercholesterolemia‐induced hypertensive rats

To investigate if increased lipid peroxidation is involved in hypercholesterolemia-induced hypertension and renal injury, we examined the effects of allopurinol, a xanthine oxidase inhibitor, on these conditions. Groups of male Sprague--Dawley rats were fed for 8 weeks with a high-cholesterol diet (4% cholesterol), a high-cholesterol plus allopurinol (10 mg/kgBW/day) diet or a normal diet. Systolic blood pressure (SBP), serum lipids, uric acid (UA) and malondialdehyde (MDA) as a measure of lipid peroxides, and urinary excretion of protein (UP) were measured after 0, 4 and 8 weeks. Urinary excretion of nitrite plus nitrate (UNOx) and iron (UFe), and MDA in the kidney were measured after 8 weeks. The renal injury was evaluated by the glomerular sclerosis score (SS). The high-cholesterol diet increased SBP, serum total cholesterol and UA, MDA in the serum and kidney, UP, UNOx, UFe and SS. Allopurinol ameliorated cholesterol-induced elevation in serum UA, MDA in the serum and kidney, UP, UNOx, UFe and SS, but did not affect SBP. Hence, our results suggest that lipid peroxidation may be involved in hypercholesterolemia-induced renal injury, and that suppression of lipid peroxidation can reduce such injury.

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.