Higher Na+-H+ exchange rate and more alkaline intracellular pH set-point in essential hypertension: EFFECTS of protein kinase modulation in platelets

Avinoam A. Livne, Orit Aharonovitz, Esther Paran

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    37 Scopus citations

    Abstract

    Na+-H+ exchange is known to be elevated in essential hypertension. To examine the mechanism of this elevation, we studied a group of 19 male hypertensive patients (mean age 46 years; systolic/diastolic blood pressure 144/99 mmHg), without medication for at least 2 weeks, and a control group of 19 male normotensives (mean age 49 years; systolic/diastolic blood pressure 118/77mmHg). Na+-H + exchange and intracellular pH set-point, at which the exchange is approximately nil, were studied spectroflurometrically in blood platelets loaded with 2′, 7′-bis carboxyethyl-5, 6-carboxyfluorescein in an isotonic medium containing 60 mmol/l sodium propionate, pH 7.35. The exchange rate (△pH per 9 s at intracellular pH 7.0) of hypertensives (0.050 ± 0.005) is significantly greater (P< 0.001) than the rate of normotensives (0.027 ± 0.003), but both groups attain similar high (˜0.074) rates when phosphorylation is stimulated by 0.5μmol/l phorbol 12-myristate 13-acetate (PMA) and similar low rates (˜0.01) when inhibited by 0.5pmol/l staurosporine. Furthermore, although hypertensive set-point is significantly (P < 0.01) more alkaline (7.33 ±0.01) than that of the normotensives (7.27 ±0.02), both groups attain a similar set-point in the presence of PMA or staurosporine (˜7.62 and ˜7.08, respectively). It is concluded that more extensive phosphorylation of the exchanger, known to be regulated by phosphorylation, is the reason for the modified properties of Na+-H+ exchange in essential hypertension, rather than larger numbers of the exchanger per cell.

    Original languageEnglish
    Pages (from-to)1013-1019
    Number of pages7
    JournalJournal of Hypertension
    Volume9
    Issue number11
    DOIs
    StatePublished - 1 Jan 1991

    Keywords

    • Hypertension
    • Intracellular pH set-point
    • Na+-H+ exchange
    • Phosphorylation

    ASJC Scopus subject areas

    • Internal Medicine
    • Physiology
    • Cardiology and Cardiovascular Medicine

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