Erythrocyte Na+,K(+)-ATPase activity does not predict therapeutic response to calcium antagonists in essential hypertension.
We investigated whether pre- and posttreatment analysis of erythrocyte membrane Na+,K(+)-ATPase (EC 3.6.1.37) activity would be a useful marker for screening hypertensive patients to determine who might benefit from treatment with calcium antagonists. Erythrocyte Na+,K(+)-ATPase activity and sodium and potassium (ENa, EK) contents were determined in controls and in patients with untreated essential hypertension before and after 4 weeks of treatment with nitrendipine. Na+,K(+)-ATPase activity was significantly (P < 0.0001) less in untreated hypertensive patients (n = 15; 104.60 +/- 29.37 nmol of phosphate produced per milligram of protein per hour) than in controls (n = 15, 171.87 +/- 34.42). After 4 weeks of nitrendipine treatment Na+,K(+)-ATPase activity was greater than in the pretreatment group: 158.13 +/- 26.80 (P < 0.001). Pretreatment ENa contents (22.34 +/- 4.77 mmol/L) were significantly (P < 0.0001) higher than in the normotensive group (13.14 +/- 3.32 mmol/L), but there was no significant difference between the controls and the posttreatment group (14.84 +/- 3.49 mmol/L). The control and pretreatment groups showed negative correlations between enzyme activity and systolic/diastolic blood pressure (P < 0.0001). The control and the posttreatment groups showed an inverse correlation between enzyme activity and ENa contents: r = -0.608 (P < 0.05) and r = -0.724 (P < 0.001), respectively. Although Na+,K(+)-ATPase is restored in hypertensive patients receiving nitrendipine treatment, relative changes in enzyme activity in relation to relative reduction in blood pressure response to treatment were not correlated.
Tanyalçin
T
T
Department of Biochemistry, Ege University School of Medicine, Bornova, Izmir-Turkey.
Kutay
F
F
Soydan
I
I
Erlaçin
S
S
D000328:Adult; D000368:Aged; D002121:Calcium Channel Blockers / Q000627:therapeutic use*; D004912:Erythrocytes / Q000201:enzymology*; D005260:Female; D006801:Humans; D006973:Hypertension / Q000188:drug therapy* / Q000201:enzymology; D008297:Male; D008875:Middle Aged; D009568:Nitrendipine / Q000627:therapeutic use; D011188:Potassium / Q000097:blood; D012016:Reference Values; D012964:Sodium / Q000097:blood; D000254:Sodium-Potassium-Exchanging ATPase / Q000097:blood*
D002121:Calcium Channel Blockers; D009568:Nitrendipine; D012964:Sodium; D000254:Sodium-Potassium-Exchanging ATPase; D011188:Potassium