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Platelet binding sites and plasma concentration of atrial natriuretic peptide in patients with essential hypertension
E L Schiffrin1, J St-Louis, R Essiambre
1Experimental Hypertension Laboratory, Clinical Research Institute of Montreal, Quebec, Canada.
Insights
In essential hypertension, elevated atrial natriuretic peptide (ANP) levels correlate with decreased ANP platelet binding sites. This finding is particularly notable in severe, untreated cases with left ventricular hypertrophy.
Area of Science:
- Cardiovascular Physiology
- Endocrinology
- Hypertension Research
Background:
- Essential hypertension is a complex cardiovascular disease.
- Atrial natriuretic peptide (ANP) plays a role in regulating blood pressure and fluid balance.
- Platelets can serve as a model system for studying ANP receptor dynamics.
Purpose of the Study:
- To investigate plasma concentrations of ANP and ANP binding site density in platelets of patients with essential hypertension.
- To explore the relationship between ANP levels, ANP platelet binding sites, and left ventricular hypertrophy in hypertensive individuals.
Main Methods:
- Measurement of plasma ANP levels in healthy controls and hypertensive patients.
- Quantification of ANP binding site density and affinity in platelets.
- Echocardiography to assess left ventricular hypertrophy and mass index.
- Analysis of ANP and platelet binding site variations with diuretic treatment.
Main Results:
- Plasma ANP levels were significantly elevated in moderate to severe untreated hypertensives compared to controls.
- Platelet ANP binding site density showed a significant inverse relationship with plasma ANP levels.
- Hypertensive patients with elevated ANP and reduced platelet ANP sites had a higher incidence of left ventricular hypertrophy.
- Diuretic therapy influenced plasma ANP and platelet ANP sites inversely.
Conclusions:
- Increased plasma ANP and decreased platelet ANP receptor density are observed in moderate to severe uncontrolled essential hypertension with left ventricular hypertrophy.
- These findings suggest a potential role for the ANP system in the pathophysiology of hypertensive cardiac remodeling.
- The ANP system in mild essential hypertension may not differ significantly from healthy individuals.
Abstract:
The plasma concentration of atrial natriuretic peptide (ANP) and the density and affinity of binding sites for ANP in platelets was investigated in patients with essential hypertension. Severe hypertensives were studied whilst still on medication. All subjects were ambulatory and were investigated after 3 days on a 135 mmol/day sodium intake. Plasma ANP levels were significantly increased from 13 +/- 1 fmol/ml in healthy normotensive controls to 39 +/- 5 fmol/ml (P less than 0.01) in moderate or severe hypertensives uncontrolled by treatment. Platelet binding sites varied in a non-linear inverse relationship to plasma concentration of ANP (r = -0.76), from 14 +/- 1 fmol per 10(9) platelets in healthy subjects to 8 +/- 1 fmol per 10(9) platelets in severe hypertensives, uncontrolled by treatment, (P less than 0.05). The latter group with elevated plasma ANP and reduced density of ANP platelet sites, had a high incidence of left ventricular hypertrophy and increased left ventricular mass index by echocardiography. When a diuretic was added or stopped, plasma ANP and ANP sites in platelets varied inversely, with lower ANP concentration in plasma and higher density of ANP receptors in platelets when receiving the diuretic. Plasma concentrations of ANP are increased and the density of ANP receptors is decreased in moderate to severe uncontrolled essential hypertensives with left ventricular hypertrophy, but neither parameter differs from those of healthy age-matched volunteers in mild essential hypertension.