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 language | English |
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Pages (from-to) | 1013-1019 |
Number of pages | 7 |
Journal | Journal of Hypertension |
Volume | 9 |
Issue number | 11 |
DOIs | |
State | Published - 1 Jan 1991 |
Keywords
- Hypertension
- Intracellular pH set-point
- Na+-H+ exchange
- Phosphorylation
ASJC Scopus subject areas
- Internal Medicine
- Physiology
- Cardiology and Cardiovascular Medicine