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Clinical Science (2003) 104, (323–327) (Printed in Great Britain)

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Sodium/lithium countertransport and intracellular calcium concentration in patients with essential hypertension and coronary heart disease

Sybille GRUSKA*, Ingo JENDRAL*, Rainer RETTIG† and Günter KRAATZ*

*Department A of Internal Medicine, Ernst Moritz Arndt University Greifswald, Loefflerstrasse 23a, D-17487 Greifswald, Germany, and †Department of Physiology, Ernst Moritz Arndt University Greifswald, Greifswalder Strass 11C, D-17495 Karlsburg, Germany

Key words: calcium signalling, cellular ion transport system, coronary heart disease, hypertension, platelet-activating factor, sodium/lithium countertransport.

Abbreviations: BMI, body mass index; [Ca²⁺]_i, intracellular calcium concentration; CHD, coronary heart disease; Na⁺/Li⁺ CT, sodium/lithium countertransport; PAF, platelet-activating factor.

Correspondence: Dr Sybille Gruska (e-mail gruska@uni-greifswald.de).

The present study was designed to test the hypothesis that enhanced intracellular calcium signalling and increased sodium/lithium countertransport (Na⁺/Li⁺ CT) activity may be associated with coronary heart disease (CHD) in non-diabetic patients with essential hypertension. Platelet-activating factor (PAF)-evoked rises in the intracellular calcium concentration ([Ca²⁺]_i) were measured in Epstein–Barr-virus-immortalized lymphoblasts from 62 hypertensive patients with CHD and 34 patients without CHD. Na⁺/Li⁺ CT activity was assessed in erythrocytes from 80 hypertensive patients with CHD and 46 patients without CHD. Baseline values of unstimulated and PAF-stimulated [Ca²⁺]_i were not significantly different between hypertensive subjects with (baseline, 126±5nmol/l; stimulated, 550±43nmol/l) and without (baseline, 125±5nmol/l; stimulated, 654±105nmol/l) CHD. Similarly, Na⁺/Li⁺ CT activity was not significantly different between the two groups (patients with CHD, 219±8µmol·l^-1·h^-1; patients without CHD, 234±10µmol·l^-1·h^-1). We conclude that intracellular signal transduction, as indicated by PAF-induced rises in [Ca²⁺]_i and Na⁺/Li⁺ CT activity, is not associated with an increased risk of CHD in non-diabetic patients with essential hypertension.

Received 27 September 2002/29 November 2002; accepted 2 January 2003

The Biochemical Society and the Medical Research Society © 2003