Effect of sodium nitrite on renal function and sodium and water excretion and brachial and central blood pressure in healthy subjects: a dose-response study.

Sodium nitrite (NaNO2) is converted to nitric oxide (NO) in vivo and has vasodilatory and natriuretic effects. Our aim was to examine the effects of NaNO2 on hemodynamics, sodium excretion, and glomerular filtration rate (GFR). In a single-blinded, placebo-controlled, crossover study, we infused placebo (0.9% NaCl) or 0.58, 1.74, or 3.48 µmol NaNO2·kg-1·h-1 for 2 h in 12 healthy subjects, after 4 days of a standard diet. Subjects were supine and water loaded. We measured brachial and central blood pressure (BP), plasma concentrations of renin, angiotensin II, aldosterone, arginine vasopressin (P-AVP), and plasma nitrite (P-[Formula: see text]), GFR by Cr-EDTA clearance, fractional excretion of sodium (FENa) free water clearance (CH2O), and urinary excretion rate of guanosine 3',5'-cyclic monophosphate (U-cGMP). The highest dose reduced brachial systolic BP (5.6 mmHg, P = 0.003), central systolic BP (5.6 mmHg, P = 0.035), and CH2O (maximum change from 3.79 to 1.27 ml/min, P = 0.031) and increased P-[Formula: see text] (from 0.065 to 0.766 µmol/l, P < 0.001), while reducing U-cGMP (from 444 to 247 pmol/min, P = 0.004). GFR, FENa, P-AVP, and the components in the renin-angiotensin-aldosterone system did not change significantly. In conclusion, intravenous NaNO2 induced a dose-dependent reduction of brachial and central BP. The hemodynamic effect was not mediated by the renin-angiotensin-aldosterone system. NaNO2 infusion resulted in a vasopressin-independent decrease in CH2O and urine output but no change in urinary sodium excretion or GFR. The lack of increase in cGMP accompanying the increase in [Formula: see text] suggests a direct effect of nitrite or nitrate on the renal tubules and vascular bed with little or no systemic conversion to NO.

Effects of atorvastatin on systemic and renal NO dependency in patients with non-diabetic stage II-III chronic kidney disease.

AIMS: Clinical trials suggest that statins have beneficial effects on the cardiovascular system independent from their cholesterol lowering properties. In patients with chronic kidney disease stage II-III, we tested the hypothesis that atorvastatin increased systemic and renal nitric oxide (NO) availability using L-N(G) -monomethyl arginine (L-NMMA) as an inhibitor of NO production. METHODS: In a randomized, placebo-controlled, crossover study patients were treated with atorvastatin for 5 days with standardized diet and fluid intake. Glomerular filtration reate (GFR), fractional excretions of sodium (FENa ), urinary excretion of aquaporin-2 (u-AQP2) and epithelial sodium channels (u-ENaCγ ), vasoactive hormones (renin, angiotensin II, aldosterone, arginine vasopressin, endothelin-1 and brain natriuretic peptide) and central blood pressure (BP) estimated by applanation tonometry were measured before and after systemic administration of the NO inhibitor L-NMMA. RESULTS: Atorvastatin caused a significant reduction in U-ENaCγ , but sodium excretion, C H 2 O , FENa and u-AQP2 were not changed by atorvastatin. L-NMMA reduced renal effect variables, including GFR, FENa and u-ENaCγ and increased brachial BP and central BP to a similar extent during both treatments. Vasoactive hormones were changed in the same way by L-NMMA during atorvastatin and placebo treatment. CONCLUSION: During, atorvastatin and placebo treatment, inhibition of nitric oxide synthesis induced the same response in brachial and central blood pressure, GFR, renal tubular function and vasoactive hormones. Thus, the data do not support that atorvastatin changes nitric oxide availability in patients with mild nephropathy. The reduced u-ENaC may reflect changes in sodium absorption in the nephron induced by atorvastatin.

Effect of vasopressin antagonism on renal handling of sodium and water and central and brachial blood pressure during inhibition of the nitric oxide system in healthy subjects.

BACKGROUND: Tolvaptan is a selective vasopressin receptor antagonist (V2R) that increases free water excretion. We wanted to test the hypotheses that tolvaptan changes both renal handling of water and sodium and systemic hemodynamics during basal conditions and during nitric oxide (NO)-inhibition with L-NG-monomethyl-arginine (L-NMMA). METHODS: Nineteen healthy subjects were enrolled in a randomized, placebo-controlled, double-blind, crossover study of two examination days. Tolvaptan 15 mg or placebo was given in the morning. L-NMMA was given as a bolus followed by continuous infusion during 60 minutes. We measured urine output(UO), free water clearance (CH2O), fractional excretion of sodium (FENa), urinary aquaporin-2 channels (u-AQP2) and epithelial sodium channels (u-ENaCγ), plasma vasopressin (p-AVP), central and brachial blood pressure(cBP, bBP). RESULTS: During baseline conditions, tolvaptan caused a significant increase in UO, CH2O and p-AVP, and FENa was unchanged. During L-NMMA infusion, UO and CH2O decreased more pronounced after tolvaptan than after placebo (-54 vs.-42% and -34 vs.-9% respectively). U-AQP2 decreased during both treatments, whereas u-ENaCγ decreased after placebo and increased after tolvaptan. CBP and bBP were unchanged. CONCLUSION: During baseline conditions, tolvaptan increased renal water excretion. During NO-inhibition, the more pronounced reduction in renal water excretion after tolvaptan indicates that NO promotes water excretion in the principal cells, at least partly, via an AVP-dependent mechanism. The lack of decrease in u-AQP2 by tolvaptan could be explained by a counteracting effect of increased plasma vasopressin. The antagonizing effect of NO-inhibition on u-ENaC suggests that NO interferes with the transport via ENaC by an AVP-dependent mechanism.

[Genetic testing in autism spectrum disorder].

Autism spectrum disorders (ASD) have a complex genetic component comprising both frequent polygenic and rare monogenic factors. Research is conducted in methods used to calculate polygenic risk scores, which are not applicable in clinical practice. Advances in genomic technology have identified several monogenic causes, and genetic testing may be offered to persons with ASD where a monogenic etiology is suspected. Herein, we provide an overview of the current knowledge and present the first national recommendation regarding genetic testing in ASD.

Mitochondrial Disease Caused by a Novel Homozygous Mutation (Gly106del) in the SCO1 Gene.

The cytochrome C oxidase assembly protein SCO1 gene encodes a mitochondrial protein essential for the mammalian energy metabolism. Only three pedigrees of SCO1mutations have thus far been reported. They all presented with lactate acidosis and encephalopathy. Two had hepatopathy and hypotonia, and the other presented with intrauterine growth retardation and hypertrophic cardiomyopathy leading to cardiac failure. Mitochondrial disease may manifest in neonates, but early diagnosis has so far been difficult. Here, we present a novel mutation in the SCO1 gene: in-frame deletion (Gly106del)with a different phenotype without encephalopathy, hepatopathy, hypotonia, or cardiac involvement. Within the first 2 h the girl developed hypoglycemia and severe chronic lactate acidosis. Because of the improved technique in whole exome sequencing, an early diagnosis was made when the girl was only 9 days old, which enabled the prediction of prognosis as well as level of treatment. She died at 1 month of age.

[Urgent revascularisation can preserve renal function in a patient with severe hypertension because of renal artery stenosis]. / Akut revaskularisering kan redde nyrefunktionen ved svær hypertension på grund af okkluderet nyrearterie.

We present a case of a 61-year-old woman with renal artery stenosis in a solitary functional kidney. The patient was admitted with recurrent severe hypertension, flash pulmonary oedema and acute kidney failure. She underwent surgical intervention, after which blood pressure and plasma creatinine level remained normal during a 11-year follow-up. Renal artery stenosis may have a serious course with flash pulmonary oedema and dialysis-dependent renal failure. Urgent revascularisation may be the only option to avoid pulmonary oedema and preserve renal function in patients with renal artery stenosis.