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Biomedical subjects

P Delva

Publications and source records attributed to P Delva.

At least 37 records · Page 2Linked to original sources
PubMed1989

High plasma levels of a ouabain-like factor in normal pregnancy and in pre-eclampsia.

Recent reports have described high levels of one or more substances which cross-react with digoxin antibodies in the serum of women with pre-eclampsia. We measured plasma ouabain-like activity and intraerythrocyte sodium and potassium concentrations, in addition to performing routine hypertensive laboratory tests, in 13 normotensive non-pregnant subjects, 15 normotensive pregnant women and 16 pre-eclamptic women (gestational age: 33-36 weeks). Plasma ouabain-like activity, measured as plasma-induced variations in ouabain binding to human erythrocytes, proved significantly higher in both groups of pregnant subjects as compared to normotensive non-pregnant women, and a significant difference was also found between pre-eclamptic and normotensive pregnant women, the former exhibiting higher plasma ouabain-like activity. No differences in intracellular sodium and potassium levels were detected among the three groups studied. Though there is reason to believe that the high plasma levels found both in normal and hypertensive pregnancy may depend on placental production, we are not in a position to define with any degree of certainty what the mechanism or mechanisms are that regulate ouabain-like factor production.

Adult↗
PubMed1989

Plasma ouabain-like activity in essential hypertensive patients and in subjects with primary aldosteronism.

Plasma from 37 essential hypertensive patients, from 11 subjects with primary aldosteronism and from 23 normotensive subjects was tested for ouabain-like activity. Despite a very substantial overlap, hypertensive patients (both essential and secondary) showed significantly higher levels of a ouabain-like plasma factor compared to normotensive controls. No substantial differences could be detected, however, between the two forms of hypertension; in particular, no significant changes were observed in the low-PRA subgroup. Our results are hardly compatible with the hypothesis that this substance may be of crucial importance in the development either of essential hypertension or of primary aldosteronism.

Adolescent↗
PubMed1989

Platelet intracellular free Ca2+ after incubation with plasma from hypertensive patients.

Variations in intracellular free calcium were measured in platelets from normal donors, incubated with plasma from hypertensive patients and from control subjects to test the hypothesis that a circulating factor might induce an increase in calcium concentration. Before incubation, plasma was heat-inactivated or ultrafiltered. Incubation both with heat-inactivated and ultrafiltered plasma failed to result in any significant modifications in intracellular free calcium. Similarly, no significant increase was observed after incubation with ouabain at concentrations ranging from 10(-7) to 10(-4) M. No significant differences were observed between platelets incubated with plasma from hypertensive as compared with control subjects. These findings are not consistent with the hypothesis that the increase in intracellular free calcium observed in platelets of hypertensive patients may be due to a plasma ouabain-like factor.

Adult↗
PubMed1988

Correlations between plasma levels of an endogenous digitalis-like substance and haemodynamic parameters measured during cardiac catheterization.

It has been postulated that one or more plasma digitalis-like compounds may play an important role in body fluid regulation and in essential hypertension, although very little is known about their possible role in general haemodynamics. We therefore measured plasma inhibition of human kidney Na+,K+-ATPase and plasma cross-reactivity with digoxin antibodies in 11 normotensive cardiopathic subjects admitted to our clinic for heart catheterization. Possible correlations with haemodynamic parameters were studied. Plasma digoxin-like activity correlated directly with left atrial pressure and with pulmonary circulation data. The ability of the plasma to inhibit Na+,K+-ATPase showed an inverse correlation with cardiac output and cardiac index. No correlations were found with any of the other parameters measured, notably systemic resistance, blood pressure and natriuresis. These findings suggest the presence of more than one substance sharing chemical properties with digitalis: (1) a substance cross-reacting with digoxin antibodies and dependent on pulmonary vascular congestion; and (2) a substance capable of inhibiting the Na+-K+ pump and present in large amounts in heart diseases with a reduced cardiac index.

Adult↗
PubMed1987

Measurement by bioluminescence technique of erythrocyte membrane Na+,K+-ATPase activity in hypertensive patients.

Erythrocyte membrane Na+,K+-ATPase activity was measured using a bioluminescence technique in 28 hypertensive patients (24 with essential hypertension, 2 with renovascular hypertension and 2 with hypertension secondary to primary hyperaldosteronism) and in 28 normotensive control subjects matched for age and sex. Erythrocyte Na+,K+-ATPase activity was significantly reduced in the patients with essential hypertension (130.9 +/- 11.4 vs. 186.6 +/- 19.5 nmol ATP/mg prot per h; mean values +/- SEM; p less than 0.05) and in the patients with secondary hypertension. A significant negative correlation was found between erythrocyte Na+,K+-ATPase and systolic blood pressure (r = -0.603; p less than 0.01), but not between Na+,K+-ATPase and plasma renin activity or plasma aldosterone levels. These data confirm the findings of a number of previous studies reporting reduced activity of erythrocyte Na+,K+-ATPase possibly related to the presence of a circulatory inhibitor of sodium pump. The method, based on ATP assay by bioluminescence, presents a high degree of specificity as well as simple, rapid execution.

Adult↗
PubMed1986

High sodium diet and circulating digitalis-like compound in the rat.

The effects of a high salt diet (8% NaCl) on blood pressure and intra-erythrocytic Na+ content were studied in Wistar rats. The ability of the plasma to inhibit the renal Na+,K+-ATPase activity and to cross-react with digoxin antibodies was also investigated. After 1 week, neither systolic blood pressure nor intra-erythrocytic Na+ content were modified, but plasma extracts slightly inhibited renal Na+,K+-ATPase (70.9 +/- 1.7 versus 76.3 +/- 2.1 mumol Pi/mg per h, P = 0.05). After 2 weeks, the plasma inhibitory activity, systolic blood pressure and intra-erythrocytic Na+ content were higher than corresponding values in control animals (65.5 +/- 1.6 versus 79.1 +/- 2.8 mol Pi/mg per h, P less than 0.001; 132 +/- 2 versus 114 +/- 4 mmHg, P less than 0.001, and 4.95 +/- 0.32 versus 3.81 +/- 0.36 mmol/l cells, P less than 0.05, respectively). After 3 months, the plasma digoxin-like immunoreactivity and its ability to inhibit the Na+ pump were elevated (68.7 +/- 7.9 versus 48.2 +/- 5.4 pg/ml, P less than 0.02; 57.8 +/- 1.8 versus 72.9 +/- 1.8 mumol Pi/mg per h, P less than 0.001, respectively) whereas intra-erythrocytic Na+ content had returned to control levels. The results demonstrated that this high salt intake led to simultaneous increases in systolic blood pressure and in the activity of a digitalis-like compound present in plasma. The inhibition of Na+,K+-ATPase was correlated with systolic blood pressure and digoxin-like immunoreactivity (r = 0.569, n = 76, P less than 0.001 and r = 0.414, n = 34, P less than 0.02, respectively).(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1985

Kinetics of bumetanide-sensitive Na+-K+ co-transport in erythrocytes of essential hypertensive patients.

Outward bumetanide-sensitive Na+-K+ cotransport was studied in the erythrocytes of 51 subjects, 24 normotensive subjects and 27 hypertensive patients, matched for sex and age. Three kinetic parameters of this cation transport system were considered: velocity of efflux at saturating internal sodium (Nai) concentrations (Vmax.), apparent affinity for sodium (K 50%) and index of co-operativity among Nai sites (Hill's n). We correlated these values with clinical and laboratory data determined routinely in hypertension. There were no significant differences between normotensive and hypertensive subjects for the values considered and we did not find any significant correlations between co-transport and clinical data.

Adolescent↗
PubMed1985

[Chronic dietary sodium overload and release of a circulating Na+-K+ pump inhibitor].

High Na+ intake has been proposed to induce a rise in the activity of a circulating inhibitor of the Na+, K+-pump. The effects on male Wistar rats of a high sodium diet (8 per cent NaCl) on the activity of such a plasma Na+, K+-ATPase inhibitor were investigated. Systolic blood pressure, body weight, urinary Na+ excretion, haematocrit, intraerythrocytic Na+ content and the activity of a Na+ dependent transport system, i.e. the uptake of 5-HT by blood platelets were measured in parallel. After one week, neither systolic blood pressure nor intraerythrocytic Na+ content were modified, but the ability of the plasma extracts to inhibit renal Na+, K+-ATPase increased (70.9 +/- 1.7 vs 76.3 +/- 2.1 mumol Pi/mg/h; p = 0.05). After two weeks, the plasma inhibitory activity, the systolic blood pressure and the intraerythrocytic Na+ content were higher than that of control animals (65.5 +/- 1.6 vs 79.1 +/- 2.8 mumol Pi/mg/h, p less than 0.001; 132 +/- 2 vs 114 +/- 4 mmHg, p. +/- 0.001 and 4.95 +/- 0.32 vs 3.81 +/- 0.36 mmol/l.cells, p less than 0.05). After three months, the ability of plasma extracts to inhibit the Na+ pump and the systolic blood pressure were still elevated (57.8 +/- 1.8 vs 72.9 +/- 1.8 mumol Pi/mg/h, p less than 0.001; 145 +/- 4 vs 118 +/- 2 mmHg, p less than 0.001) whereas intraerythrocytic Na+ content had returned to control levels and 5-HT uptake was not modified.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1984

Increased sodium-lithium countertransport in red cells of patients with Bartter's syndrome.

Erythrocyte sodium-lithium countertransport was evaluated in three adult patients with Bartter's syndrome, diagnosed on clinical and histopathological basis and on laboratory tests. As compared with age-matched control subjects, lithium effluxes to both sodium medium and to sodium-free medium were high in two patients and Na+-Li+ countertransport was significantly greater in all three patients. The relationship between increased Na+-Li+ countertransport and the proposed primary disorder of Bartter's syndrome (i.e., a primary tubular defect of chloride reabsorption) is not apparent. However, this finding favours the hypothesis of a generalized cellular membrane dysfunction of ion transport in Bartter's syndrome.

Adult↗
PubMed1984

[Hemoglobin E: report of the first 2 cases in French subjects].

Hemoglobin E has been discovered casually in the blood of two French donors: one coming from the Alsace region, the other one coming from the Champagne region. In the two cases, the hemoglobin E is in an heterozygote state and takes the place of 33 per cent of the total haemoglobin in the first and 24 per cent in the second. We investigated in their families and found that other members of these families had hemoglobin E. Each time, it was associated with a microcytosis and polycythaemia without anemy or iron deficiency. The red cells morphology shows many microspherocytes and target-cells. There is no relationship between these two families and the research of an asiatic antecedent proved negative. These two observations give a supplementary proof that the geographic repartition of the hemoglobin E is larger than what we read in the first publications and shows the interest to study the hemoglobin of unexplained polycythaemia with microcytes in the blood of blood donors.

Adolescent↗
PubMed1984

[Affinity chromatographic study of the changes in the endogenous Na+-K+-ATPase inhibitor during sodium loading in man].

Semi-purified dog kidney Na+-K+-ATPase was cross-linked with ovalbumin. This immobilized enzyme was able to hydrolyse ATP and this hydrolysis was ouabain-sensitive. It was then used in batch wise affinity chromatography for the detection of endogenous Na+-K+-ATPase inhibitor in human plasma and urine. Ammonium acetate 1 mM washed off the endogenous Na+-K+-ATPase inhibitor from the immobilized enzyme. The inhibitory activity of the eluate from hypertensive plasma was significantly higher (p less than 0.0025, n = 6) than that of normotensive plasma. Similar results were obtained (n = 3) from human urine eluates during salt loading as compared to control urine.

Animals↗
PubMed1984

[Circulating inhibitor of the Na+-K+ pump in essential hypertension. Physiological and pharmacological variations].

The presence of a circulating Na+ pump inhibitor has been assessed in 112 subjects by studying the effects of deproteinized plasma on ouabain binding to erythrocytes and/or inhibition of Na+-K+-ATPase activity. High levels of an inhibitor possessing some digitalis-like properties, were associated with essential hypertension, hypertensive heredity, treatment of hypertension with beta-blocking agents and high sodium intake. Low levels were found in hypertensives on diuretics, patients with chronic renal failure and normotensive controls. These observations are consistent with a possible role of this circulating inhibitor in the control of sodium balance and in hypertension.

Animals↗
PubMed1984

[Chronic sodium loading and circulating inhibitor of Na+,K+-ATPase in rats].

The effects of chronic sodium load on the activity of a circulating inhibitor of the Na+, K+-pump were measured in male Wistar rats. The inhibition by deproteinized plasma of renal Na+, K+-ATPase was higher in rats with high Na+ intake than in control animals (53.4 +/- 2.0 mumoles Pi.h-1 X mg-1 vs 66.6 +/- 2.6 mumoles Pi.h-1 X mg-1, p less than 0.01). The simultaneous rise in systolic blood pressure and the decrease in the hematocrit suggest that blood pressure, volemic expansion and the activity of this inhibitor may be somehow linked.

Animals↗
PubMed1984

Investigation of the endogenous Na+-pump inhibitor in essential hypertension and blood volume expansion.

The digitalis-like activities of plasma extracts from 108 patients and normal subjects were measured by their ability to compete with ouabain for binding to the digitalis sites of the Na+-pump. High levels were found in 18 of 54 untreated patients with moderate hypertension, 10 of 14 patients with end-stage renal failure and six patients with active acromegaly. These levels returned to control values after dialysis in the patients with renal insufficiency and high levels of the inhibitor, and after successful surgery and cobalt therapy in seven acromegalic patients. An increase in circulating Na+, K+-ATPase inhibitor was also found in rats after chronic sodium loading. These results indicate that levels of the circulating compound with digitalis-like properties do not result from high blood pressure but, rather, are related to blood volume and Na+ balance.

Acromegaly↗
PubMed1984

Reduction of the antihypertensive effect of captopril induced by prostaglandin synthetase inhibition.

The effects of prostaglandin synthetase inhibition by indomethacin on blood pressure and hormonal variations induced by captopril were studied in eight patients with essential hypertension and in six nonhypertensive subjects. Captopril antihypertensive effect and captopril-induced plasma renin increase were almost totally abolished by a short-term administration of indomethacin (50 mg t.i.d.). These results support the hypothesis that prostaglandins contribute to the antihypertensive effects of ACE inhibitors. It may be of clinical importance that anti-inflammatory drugs that inhibit PG-synthetase can also blunt the antihypertensive action of ACE inhibitors.

Adult↗
PubMed1983

[The effect of dopaminergic stimulation and inhibition on the urinary excretion of aldosterone and kallikrein in spontaneously hypertensive rats].

The effect on the electrolyte balance of a dopaminergic agonist (bromocriptine) and an antagonist (metoclopramide) and their effect on renal aldosterone and kallikrein excretion were investigated. Ten normotensive Wistar rats and ten spontaneously hypertensive rats (SHR-Wistar Kioto) were treated with BCR (4 mg/Kg weight b.i.d.) for 4 days; after a week of pharmacological wash-out they received MCP (0,5 mg/Kg weight b.i.d.) for 4 days. Before and after treatment and at the 2nd and 4th day of each treatment diuresis, urinary excretion of aldosterone, kallikrein, sodium, potassium and proteins were measured. During the 24-hour urine collections the rats were kept in separate metabolic cages with free access to food and water. Kallikrein urinary excretion was lower in SHR than in normotensive rats under basal conditions (p 0.05); urinary sodium, potassium, proteins and sodium/potassium rate were also reduced in SHR. After treatment with bromocriptine a further reduction in urinary kallikrein excretion was observed in SHR. After MCP all the parameters were unchanged both in normotensive rats and in SHR, but SHR showed a significant correlation between aldosterone and kallikrein excretion (p less than 0,001); in this condition it seems that in SHR the control exerted by aldosterone on kallikrein excretion is greater than the one exerted by dopamine. It may indicate a defect of the natriuretic and vasodilator dopaminergic system in spontaneously hypertensive rats.

Aldosterone↗