Study identifies hypertension patients who can benefit from the little used diuretic...( of the devastating health consequences...)

Methodology
The initial step was an assessment of whether peripheral blood lymphocytes expressing ENaC (epithelial Na+ channels) similar to the same expressed by renal cells could be linked to hypertensive etiologies. The second was to test the hypothesis that specific inhibition of hyperactive ENaC with amiloride could improve hypertension.

To test their assumption, the researchers obtained blood samples from patients with normal blood pressure and hypertensive patients. Volunteers were between ages 19 and 70 and were recruited from the University of Alabama-Birmingham Hypertension Clinic. Blood samples were taken from subjects diagnosed as normotensive (unmedicated blood pressure <140/90 mmHg and no family history of hypertension); controlled hypertensive (having a blood pressure <140/90 mmHg while taking a single hypertensive medication); and refractory hypertensive (blood pressure >140/90 mmHg despite ongoing therapy with three or more anti-hypertensive agents). Nine subjects with refractory hypertension were prescribed amiloride for a four-week period.

Subjects were assessed after two weeks and their dosage increased to five milligrams, twice daily. Lymphocytes were examined to determine whether ENaC was hyperactive. They were then divided into four samples and frozen at -84C before undergoing electrophysiological examination. A determination of normal or abnormal ENaC regulation was based on the basal channel activity and a response to cyclic AMP. Blood pressure was compared before and after treatment.

Results
Cells from blood samples of 106 volunteers were examined using a whole cell patch clamp (a technique used in the study of ion channels in which the movement of ions across a small patch of isolated membrane is measured when the membrane is electrically polarized or hyperpolarized and maintained at that
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Contact: Donna Krupa
djkrupa1@aol.com
703-527-7357
American Physiological Society
19-Aug-2002