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Intracellular cation concentrations in essential hypertension and chronic renal failure
J M Krzesinski1, F Du, G Rorive
1Nephrology-Hypertension Unit, C.H.U.- Sart Tilman, Liege, Belgium.
Insights
Essential hypertension and chronic renal failure patients show abnormal cellular ion levels. Hemodialysis and antihypertensive treatments partially correct these abnormalities, linking cellular calcium reduction to blood pressure decrease.
Area of Science:
- Nephrology
- Cardiovascular Medicine
- Cellular Physiology
Background:
- Essential hypertension and chronic renal failure (uremia) are associated with altered cellular ion homeostasis.
- Platelet cytosolic free calcium and pH, along with erythrocyte sodium and calcium concentrations, are potential biomarkers for these conditions.
Purpose of the Study:
- To investigate basal and post-treatment erythrocyte and platelet ionic concentrations and calcium-ATPase activity in normotensive controls, hemodialysis patients, and essential hypertensive patients.
- To explore the effects of hemodialysis and antihypertensive medications on these ionic parameters.
Main Methods:
- Measurements of erythrocyte sodium, calcium, magnesium, and calcium-ATPase activity.
- Assays for platelet cytosolic free calcium and pH.
- Comparison between normotensive controls, hemodialysis-dependent chronic renal failure patients, and essential hypertensive patients before and after treatment.
Main Results:
- Uremic and hypertensive patients exhibited higher platelet calcium and lower pH than controls. Erythrocyte sodium, calcium, and magnesium were elevated in uremia, with reduced calcium-ATPase activity.
- Hemodialysis partially normalized platelet pH and some ionic abnormalities. Antihypertensive treatments showed a trend towards normalizing intracellular calcium.
- Correlations were found between weight loss and decreased platelet calcium/erythrocyte sodium, and between blood pressure decrease and increased calcium-ATPase activity or reduced intracellular calcium.
Conclusions:
- Essential hypertension and uremia present with distinct cellular ionic abnormalities in platelets and erythrocytes.
- Hemodialysis and antihypertensive therapies can partially correct these ionic disturbances, with specific links between treatment efficacy and blood pressure reduction.
- Cellular calcium reduction is associated with blood pressure decrease in essential hypertension.
Abstract:
The aim of this study was to test basal and after treatment erythrocyte sodium and calcium concentrations, and calcium-ATPase activity and platelet cytosolic free calcium and pH in 20 normotensive controls, 20 hemodialysis-dependent chronic renal failure patients and in 18 essential hypertensives. Prior to treatment, essential hypertensive and uremic patients presented similar higher platelet calcium concentrations and lower pH than the normotensive control group. The erythrocyte sodium, calcium, and magnesium concentrations were only significantly elevated in chronic renal failure, with a significant decrease in the calcium-ATPase activity in the latter population. Hemodialysis partially reversed these intracellular ionic abnormalities with normalization of platelet pH. Significant correlations have been noted between weight loss and decreases in platelet calcium concentration (r = 0.60, p < 0.01) or in erythrocyte sodium (r = 0.50, p < 0.05). The systolic blood pressure decrease was only correlated to the increase in calcium-ATPase activity (r = 0.57, p < 0.05). Antihypertensive treatment (captopril and nifedipine) only tended to normalize the intracellular calcium concentration with correlation between the decrease of the latter and blood pressure decrease (r = 0.64 for the systolic blood pressure and 0.68 for the diastolic blood pressure, p < 0.01). Thus, in essential hypertension and in uremia, some cellular ionic abnormalities exist in platelets in baseline condition. Moreover, in uremia, erythrocyte presents abnormal ionic pattern. Some, but not all of these abnormalities could be corrected by treatment affecting blood pressure (cellular calcium) in essential hypertension or by hemodialysis (cellular sodium, calcium, and pH). In the latter treatment, the changes are linked to extracellular fluid modification. In essential hypertension, the intracellular calcium reduction was linked to blood pressure decrease.