[Calcium pump changes in patients with essential arterial hypertension]

Area of Science:

• Cardiovascular Physiology
• Biochemistry
• Nephrology

Background:

• Transmembrane Ca2+ fluxes are crucial for cellular function.
• The Ca2+-dependent ATPase plays a significant role in regulating intracellular Ca2+ levels.
• Elevated cytosolic Ca2+ has been observed in essential hypertension.

Purpose of the Study:

• To investigate the kinetics of the Ca2+ pump in erythrocytes of essential hypertensive patients.
• To determine if abnormalities in Ca2+ transport are associated with hypertension.
• To identify subgroups of hypertensive patients with specific ion transport defects.

Main Methods:

• Kinetic study of the Ca2+ pump using strontium (Sr2+) as a calcium analogue in intact erythrocytes.
• Analysis of 49 essential hypertensive patients and 27 normotensive controls.
• Intracellular Ca2+ and Sr2+ concentrations modulated using the A-23187 ionophore.

Main Results:

• Hypertensive patients exhibited a significantly increased maximal efflux rate (Vmax) for Sr2+ compared to controls.
• Mean values for the apparent dissociation constant for intracellular Ca2+ (KCa) were also elevated in essential hypertensives.
• A subgroup of 32.6% of hypertensive patients showed increased KCa values, correlating with higher age, serum creatinine, and uric acid levels, and also higher Vmax.

Conclusions:

• Essential hypertensive patients display heterogeneity in ion transport abnormalities.
• Abnormalities of the Ca2+-dependent ATPase were identified in approximately 33% of essential hypertensive patients.
• These patients with Ca2+ pump dysfunction are typically older and have elevated serum creatinine and uric acid levels.