Search

Purpose: Leptin is associated with cardiovascular risk factors (e.g. hypertension, insulin resistance, kidney disease and excess body weight). Experimental studies showed that leptin might affect serum uric acid, by modulation of the uric acid excretion. However, there are few observational data on the relationship between leptin and uric acid in the general population. Therefore, the aim of the present study was to evaluate the relationship between leptin and uric acid and its excretion in a large middle-aged male general population. Methods: A sample of 930 adult male individuals (mean age: 52 years) without therapy for high uric acid was included in the analysis (the Olivetti Heart Study). Results: Uric acid was significantly and positively associated with blood pressure, BMI, waist circumference, insulin resistance, C-reactive protein and leptin (p?<?0.01), while inversely with renal function (p?=?0.01). The multivariate analysis confirmed the association between leptin and uric acid after adjustment for potential confounders (p?<?0.01). After division for adiposity, this trend was confirmed separately for normal weight and excess body weight participants. Moreover, leptin was inversely associated with excretion of uric acid (p?<?0.01), also in multivariate analysis (p?=?0.03). Conclusion: The results of this study indicate a positive association between circulating leptin levels and uric acid, independently of potential confounders, both in normal and excess body weight men. Furthermore, an inverse association between leptin and uric acid excretion was detected.

1. The fractional clearance of lithium (FCLi) has been validated in the rat under controlled experimental conditions as a reliable indicator of sodium and water handling in the proximal tubule. The purpose of the present study was to evaluate some key methodological aspects related to the use of the FCLi in clinical and epidemiological investigation. 2. FCLi was determined in healthy normotensive, or in some cases, in borderline/mild essential hypertensive subjects, by a morning urine collection obtained between 09.00 and 13.00 hours after a 300 mg oral lithium carbonate load (= 8.1 mmol of elemental lithium). 3. The ratio of intra-individual to inter-individual variance of FCLi, measured in free-living subjects on unrestricted diet, was shown to be low enough (0.33) to allow adequate characterization of individuals in a population with a single measurement, or at most with two (compared with at least four measurements needed to characterize the fractional excretion of sodium). 4. The remarkable influence of dietary sodium intake on FCLi, demonstrated under metabolic ward conditions, might explain a major portion of the observed intra-individual variability. 5. At the dosage employed in the present study, oral lithium administration did not affect the renal handling of sodium, potassium or calcium. Likewise, it did not induce any change in a series of 17 metabolic parameters and indicators of renal and liver function. 6. It is concluded that the FCLi may be a safe and useful tool for the clinical and epidemiological investigation of renal sodium and water handling. The possibility of a confounding effect of dietary sodium intake, however, should be kept in mind.

We evaluated the effect of the dihydropyridine Ca-channel blocker nitrendipine on blood pressure (BP) and electrolyte urinary excretion after acute and chronic therapy in 33 patients with different NaCl sensitivity as assessed by a modification of the test of Grim and colleagues. Acute nitrendipine administration significantly reduced BP in the group as a whole, although the hypotensive effect was greater in patients with greater NaCl sensitivity; this difference was still evident after 1 month of chronic therapy. Futhermore, urinary sodium and calcium excretion significantly increased in the 3 h after nitrendipine administration during both acute and chronic therapy; these effects on electrolyte excretion were independent of the NaCl sensitivity of the subject.

The present report evaluates a method for the determination of the maximal velocity of the outward sodium, potassium, chlorine (Na-K-Cl) cotransport in erythrocytes. The loading procedure was carried out using the ionophore nystatin. The technical error for this assay, based on concurrent analysis of randomized blind duplicate samples, was 8.04% of the sample mean and 27.5% of the sample standard deviation. The assay was stable over time and reproducible. Fasting was not necessary. The ratio of intra- to interindividual variances was small. The cells can be safely preserved in an appropriate preservation solution without modification of the ion transport assay. The assay appears to be adequate for use in large-scale field trials.

Previous short-term studies of muzolimine (a diuretic with frusemide-like activity) had shown that it did not induce a significant change in the serum potassium concentration. In the present study sodium and potassium handling and other metabolic variables have been compared during 16 weeks of therapy with muzolimine and chlorthalidone, a thiazide-like diuretic. During muzolimine treatment, plasma and red cell potassium concentrations remained unchanged, while a significant fall in potassium occured with chlorthalidone. Neither drug affected the activity of sodium-potassium cotransport or sodium-lithium countertransport in red cells in vitro. Muzolimine and chlorthalidone had similar effects on arterial pressure and on the other metabolic variables tested.

As a results of the MINISAL study, that indicated an excess salt intake in Italy, we planned a “The Lower Salt Community Project”, a trial of feasibility, acceptability and safety of a strategy of moderate and gradual reduction of salt intake (15 over 18 months) in an Italian community in the area of Cilento.

A significant and positive association between red blood cell sodium lithium countertransport (Na-Li CT) and blood pressure has been found in numerous studies. However, the majority of the studies presented to date are cross-sectional in nature and limited information exists on the longitudinal association between Na-Li CT and blood pressure. The present study analyzes the longitudinal association between Na-Li CT and blood pressure in 124 men participants in the Olivetti Heart Study and normotensives at the baseline examination. The Na-Li CT measured at the 12 year follow-up examination was analyzed in regard to the blood pressure changes over time during the 12 year follow-up. Na-Li CT (measured at follow-up examination) was positively related to changes over time in systolic pressure (r = 0.16) and diastolic pressure (r = 0.07) and changes in body mass index (r = 0.18). When blood pressure changes over time were analyzed by tertiles of Na-Li CT, the highest tertile group exhibited on the average significantly higher increases in systolic blood pressure compared with participants of the lowest tertile of the Na-Li CT distribution. This difference remained statistically significant after adjusting for the changes in weight observed during the 12 years follow-up. These findings indicate that the Na-Li CT distribution is related to blood pressure changes over time. However, the usefulness of Na-Li CT as a predictor of incidence of hypertension remains to be established. Am J Hypertens 1996;9:1132–1135