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Urinary Osmolality (urinary + osmolality)
Selected AbstractsInteractions between maternal subtotal nephrectomy and salt: effects on renal function and the composition of plasma in the late gestation sheep fetusEXPERIMENTAL PHYSIOLOGY, Issue 2 2008Amanda C. Boyce Effects of altered maternal salt intake between 122 and 127 days gestation (term is 150 days) were studied in eight fetuses carried by ewes which had renal insufficiency caused by subtotal nephrectomy (STNxF) and seven fetuses carried by intact ewes (IntF). Plasma sodium and osmolality were increased in ewes with subtotal nephrectomy on a high-salt intake (0.17 m NaCl in place of drinking water for 5 days; P < 0.05). The STNxF had normal body weights. A high maternal salt intake did not affect fetal blood pressure or heart rate. Plasma osmolality was higher in STNxF (P < 0.001), and plasma sodium and osmolality were increased by high salt (P < 0.001 and P < 0.04, respectively). The STNxF had higher urinary osmolalities (P= 0.002), which were also increased by a high maternal salt intake (P= 0.03). Renal blood flow fell in STNxF in response to a high maternal salt intake, but increased in IntF (P= 0.003). In STNxF but not IntF, glomerular filtration rate and urinary protein excretion were positively related to fetal plasma renin levels (P, 0.01). It is concluded that the salt intake of pregnant ewes with renal insufficiency affects maternal and fetal osmolar balance, fetal plasma sodium and fetal renal function. Since STNxF also had altered renal haemodynamic responses to high maternal salt and evidence of renin-dependent glomerular filtration and protein excretion, we suggest that interactions between dietary salt and pre-existing maternal renal disease impair glomerular integrity and function in the fetus. [source] Protective Effects of Glycyrrhizin on Gentamicin-Induced Acute Renal Failure in RatsBASIC AND CLINICAL PHARMACOLOGY & TOXICOLOGY, Issue 3 2003Eun-Jin Sohn Polyuria in rats with gentamicin-induced acute renal failure was associated with down-regulation of renal aquaporin 2 in the inner and outer renal medulla, and cortex. Glycyrrhizin administration restored the expression of aquaporin 2 with paralleled changes in urine output. Changes in renal functional parameters, such as creatinine clearance, urinary osmolality, and solute-free reabsorption, accompanying acute renal failure were also partially restored after administration of glycyrrhizin. Histological changes in rats with gentamicin-induced acute renal failure were also abrogated by glycyrrhizin treatment. The above results suggest that glycyrrhizin treatment could ameliorate renal defects in rats with acute renal failure induced by gentamicin. [source] Renal concentrating capacity as a marker for glomerular filtration rateACTA PAEDIATRICA, Issue 1 2008Víctor M García Nieto Aim: We have studied 160 children with a variety of renal diseases, 14 of them with chronic renal failure (CRF), to evaluate maximum urinary osmolality as a predictor of glomerular filtration rate (GFR) testing the hypothesis that a normal GFR is necessary to have a normal urinary concentrating capacity. Methods: All patients had a serum creatinine measured. GFR was calculated according to the Schwartz formula. All patients underwent desmopressin (DDAVP) test to evaluate renal concentrating capacity. Results: Patients with CRF were unable to concentrate the urine beyond 486 mosm/kg whereas all patients with a normal concentrating capacity (urine osmolality > 835 mosm/kg) had a normal GFR. Desmopressin test sensitivity to detect CRF was 100% and specificity 70.5%. A significant negative correlation was found between urinary osmolality after DDAVP administration and serum creatinine levels and between urinary volume corrected by 100 mL of GFR (V/GFR) and urinary osmolality. Conclusion: In our series, a normal concentrating capacity was always associated with a normal GFR while all patients with decreased GFR had a concentrating capacity defect. Thus, in the evaluation of infants and children with renal disease, the finding of a normal urinary concentrating capacity will suggest and intact glomerular and tubular function. [source] Urinary excretion of the aquaporin-2 water channel exaggerated in pathological states of impaired water excretionCLINICAL ENDOCRINOLOGY, Issue 2 2001Takako Saito OBJECTIVE The present study was undertaken to determine whether the hydro-osmotic action of arginine vasopressin (AVP) is exaggerated in pathological states of impaired water excretion by measuring urinary excretion of the aquaporin-2 (AQP-2) water channel. PATIENTS AND MEASUREMENTS Eighteen hyponatraemic patients with impaired water excretion and 12 control subjects were studied during an acute oral water load (20 ml/kg body weight). RESULTS In the patient group plasma AVP levels were 1·6 pmol/l, relatively high compared to plasma osmolality of 279·8 mmol/kg. Urinary excretion of AQP-2 under ad libitum water drinking was 41·1 fmol/umol creatinine in the patient group, a value significantly greater than that of 21·7 fmol/,mol creatinine in the control subjects. The acute water load verified the impairment in water excretion in the patient group, as the excretion of the water load was only 28·2% (control, 77·3%, P < 0·001) and the minimum urinary osmolality was as high as 437·3 mmol/kg (control, 122·9 mmol/kg, P < 0·001). Also, the minimum urinary excretion of AQP-2 was significantly greater in the patient group than that in the control. There was a positive correlation between plasma AVP levels and urinary excretion of AQP-2 in the control subjects (r = 0·56, P < 0·01). In contrast, the urinary excretion of AQP-2 was exaggerated compared to the respective plasma AVP levels in the patient group, and thus the positive correlation disappeared. CONCLUSION These results indicate that hydroosmotic action of AVP is exaggerated more than that expected from plasma AVP levels in pathological states of impaired water excretion, with non-suppressible, but normal, arginine vasopressin levels in spite of the hypo-osmotic condition. [source] | ||||||||||