The role of potassium in control of blood pressure.

Extra potassium intake has been found to be a determinant of blood pressure for epidemiological and experimental reasons. People with hypertension have a small fall in blood pressure with added potassium. Potassium chloride (48 mmol/day) was given to 36 male patients with high blood pressure; 5 did not comply with therapy. In the entire group of patients, potassium chloride had no significant effect on blood pressure, but prevented the rise in blood pressure and pulse rate produced by posture. In patients with a urinary Na+ excretion less than 75 mmol per 10 mmol creatinine, potassium chloride had no effect on supine blood pressure, but prevented the rise in blood pressure and pulse rate with standing. In those on a high sodium intake, potassium chloride lowered both the systolic and diastolic pressures. In sodium-responsive subjects, potassium chloride prevented the rise in blood pressure induced by sodium chloride but had no significant effect on blood pressure when on a low sodium intake. These results indicate that potassium reduces the rise in blood pressure caused by sodium chloride and reduces the increased sympathetic postural response seen in people on a low sodium intake.