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Biomedical subjects

C Zoccali

Publications and source records attributed to C Zoccali.

At least 73 records · Page 4Linked to original sources
PubMed1996

Reproducibility of the response to short-term low salt intake in essential hypertension.

BACKGROUND: The reproducibility of the arterial pressure response to change in salt intake in essential hypertensives has been little investigated. OBJECTIVE: To study the reproducibility of the response to salt in 14 untreated patients with mild essential hypertension. METHODS: After a run-in phase (1 month), each patient ingested, in random order and with cross-over, 1 week of high salt intake (170 mmol/day) and 1 week of low salt intake (40 mmol/day). The identical experimental protocol was then repeated after an average interval of 3.4 months. Arterial pressure was measured (clinic arterial pressure and 24 h ambulatory monitoring) on the seventh day of each diet period. The reproducibility of the arterial pressure response was assessed in terms the intraclass correlation coefficient and the K statistics. RESULTS: There was a good compliance with the dietary prescription because the urinary Na excretion was on average very close to the prescribed intake both during the first and during the second salt intake period. Both clinic and 24 h arterial pressure fell significantly (P < 0.01) and to the same extent in the low-salt phases of the study. Clinic arterial pressure was consistently higher than 24 h ambulatory arterial pressure but the average changes induced by salt depletion were similar. The variability of 24 h ambulatory arterial pressure at constant salt intake was lower than that of clinic arterial pressure. However, the arterial pressure response to salt showed the same variability with the two methods. The reproducibility of the dichotomous classification of patients into salt-sensitive and -resistant was low both in terms of 24 h ambulatory and in terms of clinic blood pressure. CONCLUSION: Although on rechallenging the average arterial pressure response to salt remains unchanged in essential hypertensives, the individual responses are variable and the reproducibility of the dichotomous classification is unsatisfactory. The problem of dichotomizing patients into salt-sensitive and -resistant ones is only in very little part resolved by more precise arterial pressure estimates.

Adult↗
PubMed1996

Does high salt intake cause hyperfiltration in patients with essential hypertension?

In animal models of salt-dependent hypertension, hyperfiltration is associated with a faster decline in renal function and there is evidence that in hypertensive man, increased creatinine clearance is a marker of early hypertensive nephropathy. We have studied the influence of salt intake on the glomerular filtration rate (GFR) (Creatinine Clearance) in 14 patients with mild hypertension. Each patient was studied in random order and according to a crossover design, at habitual salt intake, at high salt intake (ie habitual +50/100 mmol/day) and at low salt intake (habitual -50/100 mmol/day). Protein, calcium and potassium intake was fixed across the three study periods. The control group was formed by seven healthy subjects. High salt intake, caused a significant (P < 0.01) increase in 24 h mean arterial pressure (MAP) and the expected suppression in plasma renin activity (PRA) and in plasma aldosterone. Seven patients were classified as salt-sensitive. The GFR was significantly higher (P < 0.01) at high salt intake (125 +/- 10 ml/min) than at habitual (113 +/- 7 ml/min) and at low salt intake (97 +/- 6 ml/min). On aggregate urinary salt excretion was significantly related with the GFR (P < 0.01 by correlation analysis for repeated observations) and the slope of this relationship predicted that a 100 mmol/day increase in salt intake is associated with the 14.6 ml/min rise in the GFR. The relationship between GFR and 24 h urinary salt in salt sensitive patients did not differ from that in salt resistant patients. The GFR response to salt loading was largely independent of the renin-aldosterone system. No change in arterial pressure nor in GFR was observed in healthy subjects. At fixed protein intake, changes in salt intake in the physiological range are associated with important GFR variations in mild hypertensives. As long as hyperfiltration in mild hypertension is a predictor of renal function deterioration, high salt intake, independent of the effect of arterial pressure, could be a factor that contributes to nephronic obsolescence in patients with essential hypertension.

Adult↗
PubMed1995

Urinary and plasma endothelin 1 in essential hypertension and in hypertension secondary to renoparenchymal disease.

An alteration in renal metabolism of endothelin may contribute to hypertension in the SHR and it has been shown that the excretion rate of endothelin is reduced in patients with essential hypertension. We measured plasma and urinary endothelin 1 (ET-1) in 20 untreated essential hypertensives with normal renal function, in eight normotensive healthy subjects, and in 13 hypertensive patients with primary renoparenchymal disease. Plasma ET-1 was higher (P < 0.01) in essential hypertensives (median 1.69, interquartile range 1.2-3.3 pg/ml) than in normal subjects (0.84, 0.37-1.10 pg/ml) but significantly less (P < 0.01) than in hypertensives with renoparenchymal disease (3.57, 1.45-9.52 pg/ml). ET-1 levels slightly correlated with diastolic pressure in essential hypertensives (r = 0.43, P < 0.05) and tended to be correlated with systolic pressure in hypertensives with renal disease (r = 0.47, P = 0.08). ET-1 excretion in essential hypertensives (137, 99-154 ng/24 h) and in normal subjects (120, 62-150 ng/24 h) was significantly lower than in renal hypertensives (191, 123-241 ng/24 h). The ET clearance/GFR ratio (ClET/GFR) was markedly reduced (30%, 21-67%) in essential hypertensives and substantially raised in renal hypertensives (164%, 86-314%) in comparison with normal subjects (83%, 35-94%). Since the ClET/GFR ratio should be 100% if all filtered ET-1 is excreted, the data indicate that ET-1 is synthesized at a reduced rate and/or broken down at an enhanced rate by the kidney in essential hypertension and confirm that there is a high ET-1 generation rate in remnant nephrons in hypertension secondary to renal disease.

Adolescent↗
PubMed1994

Assessment of the salt-arterial pressure relationship in mild hypertensive subjects by 24-hour ambulatory monitoring.

1. We have assessed the relationship between salt intake and 24 h ambulatory arterial pressure in middle aged men with essential hypertension. 2. During the run-in phase (1 month) we estimated the habitual sodium intake (the average Na excretion of two 24 h urine collections) of each participant (n = 14). In the randomized and crossover part of the study we contemplated a 'habitual' sodium intake phase, in which each individual received a fixed diet (about 30 mmol of Na+ and 65 mmol of K+) with additional salt so as to equalize the average intake of the run-in phase, as well as high sodium phases (habitual intake +50 and +100 mmol/day) and low sodium phases (habitual intake -50 and -100 mmol/day). After the trial, 10 patients underwent an additional week of fixed salt intake to assess the reproducibility of 24 h ambulatory monitoring. 3. Average 24 h arterial pressure at habitual sodium intake was significantly lower than that at high intake and significantly higher than at low sodium intake. Clinic arterial pressure showed similar trends but only systolic pressure changes at low sodium intake achieved statistical significance. 4. Analysis of the data on an individual basis showed a linear increase in 24 h mean arterial pressure with increasing levels of sodium intake in all but two cases (flat response in one case and a non-linear rise in the other case). The response pattern of clinic measurements was much less homogeneous. In the aggregate, there was a highly significant linear trend for ambulatory arterial pressure to rise with increasing levels of salt intake.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1994

Influence of extracellular volume expansion on circulating PTH1-84 in subjects with mild essential hypertension.

The effect of acute volume expansion by saline (1 L/40 min) on serum parathyroid hormone (PTH) concentration was studied in 28 subjects with mild essential hypertension. At the zenith volume expansion there was a significant increase in systolic pressure (7 +/- 2 mm Hg, P < .01) while diastolic pressure and heart rate showed minor (NS) variations. The rise in systolic pressure was accompanied by a significant (P = .02) decrease in plasma ionized calcium (from 1.12 +/- 0.03 to 1.08 +/- 0.03 mmol/L) and by a marked PTH increase (from 36 +/- 3 to 60 +/- 4 pg/mL, P < .01). The arterial pressure variations were independent of changes in serum PTH. In a second experiment (n = 11), aimed at preventing the changes in calcium concentration brought about by hemodilution, we infused the same volume of saline with the addition of 1.25 mmol of elemental calcium. In this study PTH showed a small, nonsignificant, decrease while systolic pressure changes were similar to those of the first study (ie, an isolated 9 +/- 4 mm Hg increase in systolic pressure). In a third experiment (n = 7), aimed at studying the effect of raised plasma PTH concentration in isocalcemic conditions, PTH1-38 was continuously infused (1 ng/kg/min) during the volume expansion phase performed with the same solution as used in the second experiment. The hemodynamic changes were again identical to those of the other studies (an isolated 9 +/- 3 mm Hg increase in systolic pressure).(ABSTRACT TRUNCATED AT 250 WORDS)

Blood Pressure↗
PubMed1994

Influence of ANF on the cardiovascular response to volume expansion in haemodialysis patients.

Plasma ANF concentration in uraemic patients is very sensitive to changes in extracellular volume. It is unknown, however, if the release of this vasoactive hormone has a compensatory role in the haemodynamic response to extracellular volume expansion in these patients. We investigated the effect of isolated ultrafiltration followed by isovolumic re-expansion by saline in seven haemodialysis patients. The experiment was repeated on two occasions and the UF rate as well as the rate of volume re-expansion in the two studies were accurately matched. During the phase of volume re-expansion, we infused either ANF (0.83 microgram/min) or a placebo, in random order and cross-over. Central venous pressure, arterial pressure, haematocrit, and plasma ANF concentration were measured in baseline conditions, after ultrafiltration, and 0, 15, and 30 min after isovolumic re-expansion. In the control experiment (placebo), isolated ultrafiltration caused a marked reduction in central venous pressure and in arterial pressure and a pronounced haematocrit increase. These changes were reversed by volume re-expansion. In the active experiment, during the phase of volume re-expansion ANF infusion doubled plasma ANF concentration as compared to control experiment but it did not affect the ongoing haemodynamic response nor the haematocrit changes. Doubling of plasma ANF concentration has no influence on the haemodynamic and microcirculatory adaptations to acute volume expansion in haemodialysis patients. The data indicate that it is unlikely that raised plasma ANF concentration has a major role in the cardiovascular response to acute extracellular volume expansion in these patients.

Adult↗
PubMed1994

The influence of salt intake on plasma calcitonin gene-related peptide in subjects with mild essential hypertension.

BACKGROUND: Calcitonin gene-related peptide is a pleiotropic neuropeptide with potent vasodilatory properties, which interferes with renin release and might participate in cardiovascular homeostasis. DESIGN AND METHODS: We studied the influence of salt intake on the plasma concentration of calcitonin gene-related peptide, parathyroid hormone and on the renin-aldosterone system in 15 patients with mild hypertension. Each participant was studied after 1 week of high salt intake (200 mmol/day) and after 1 week of low salt intake (50 mmol/day). The order of the two diet periods was randomized and crossover. Plasma calcitonin gene-related peptide concentration was measured by radioimmunoassay after pre-extraction by reverse chromatography. Seven patients were classified as salt-sensitive and eight as salt-resistant. RESULTS: In the whole group the low salt intake caused a significant decrease in arterial pressure and the expected increase in plasma renin activity and in plasma aldosterone concentration. Such changes were accompanied by a significant increase in plasma calcitonin gene-related peptide. In salt-resistant patients in the sodium-replete state calcitonin gene-related peptide levels tended to be reduced in comparison with salt-sensitive patients. Sodium depletion, however, caused a more pronounced rise in plasma calcitonin gene-related peptide in salt-resistant hypertensives, who attained levels close to those in salt-sensitive hypertensives. Interestingly, in salt-resistant hypertensives changes in plasma calcitonin gene-related peptide were closely related to plasma renin activity (r = 0.71, P = 0.003), whereas no such correlation was found in salt-sensitive patients. Parathyroid hormone was not influenced by changes in salt intake. CONCLUSIONS: In subjects with mild hypertension calcitonin gene-related peptide is sensitive to changes in salt intake in the physiological range. Such a response seems to be linked to the individual arterial pressure response to salt, because salt-resistant patients showed reduced calcitonin gene-related peptide levels in the sodium-replete state and a more pronounced calcitonin gene-related peptide increase, closely related to plasma renin activity, during sodium deprivation.

Adult↗
PubMed1993

Influence of cardiovascular damage and residual renal function on plasma endothelin in chronic renal failure.

To study the influence of cardiovascular damage on plasma endothelin in chronic renal failure, we have measured the plasma concentration of this peptide in 32 uremic patients (7 undialyzed uremics, 8 CAPD patients and 16 hemodialysis patients) and in 9 healthy subjects. Sixteen patients had severe cardiovascular damage while the other 16 had no cardiovascular involvement. Endothelin was markedly raised (p < 0.01) in the uremic group as a whole (13.9 +/- 2.6 pmol/l) in comparison with the group of healthy subjects (8.6 +/- 1.6 pmol/l). Hemodialysis patients displayed endothelin levels much higher (p < 0.01) than CAPD patients and undialyzed uremics. Endothelin was directely related with BUN (r = 0.37) and with serum creatinine (r = 0.52) in dialysis patients. Similar correlations were also found in undialyzed uremics. Plasma endothelin was almost identical in patients with severe cardiovascular damage (15.5 +/- 1.6 pmol/l) and in those without cardiovascular involvement (15.9 +/- 2.6 pmol/l). There was no relationship between arterial pressure and plasma endothelin. Residual renal function is an important determinant of circulating endothelin even at very advanced stages of renal insufficiency. It appears unlikely that atherosclerosis plays a major role in the pathogenesis of high plasma concentration of this peptide in uremic patients.

Adult↗
PubMed1993

Parathyroidectomy and blood pressure in hemodialysis patients.

To assess whether parathyroidectomy (PTx) affects blood pressure (BP) in hemodialysis (HD) patients, we studied 11 uremics on HD treatment for 8.2 +/- 0.9 years who underwent successful PTx. As the control group, we selected 11 HD patients not submitted to PTx, matched with the study group for sex, age, years on HD, dialysis procedure and BP values. In the controls, BP and body weight did not change during the 2 years of observation. In the patients, BP remained stable in the year before PTx. PTx caused a progressive reduction in BP in 7 of the 11 patients. The fall was significant from the 3rd quarter onward (mean BP values before PTx: 139/82 mm Hg, 1 year after PTx: 122/75 mm Hg). The magnitude of the hypotensive effect of PTx was related to the pre-PTx systolic BP value (r = -0.70, p = 0.016). PTx also caused a significant progressive increase in body weight (1.56 +/- 0.57 kg 1 year after PTx). In conclusion, PTx causes BP fall in HD patients regardless of whether their preintervention values are normal or increased. The BP reduction occurs in concomitance with a consistent increase in body weight. BP variations are clinically relevant and may be related to the post-PTx calcium efflux from the vessel wall.

Alkaline Phosphatase↗
PubMed1993

Genetic mapping in the Xp11.2 region of a new form of X-linked hypophosphatemic rickets.

Human X-linked dominant hypophosphatemic rickets (HPDR I) is characterized by hypophosphatemia, hyperphosphaturia, abnormal vitamin D metabolism, and rickets/osteomalacia. Two closely linked hypophosphatemic genes, hypophosphatemia (Hyp) and Gyro (Gy), are known on the mouse X chromosome. The Hyp phenotype is the equivalent of the human X-linked hypophosphatemia, while the human equivalent of the Gyro mouse has not been unambiguously identified. We observed an Italian four-generation pedigree with a new form of X-linked recessive hypophosphatemic rickets (XLRH). We demonstrated that HPDR I and XLRH are two different X-linked genes and that XLRH maps in the Xp11.2 region at 0% recombination fraction from the DXS1039 locus. We discuss this new finding in relation to the identification of the human equivalent of the Gyro mouse and to the recent mapping in Xp11.22 of another X-linked recessive renal disorder named Dent disease.

Adult↗