Potassium infusion attenuates avoidance-saline hypertension in dogs.
Previous studies have shown that a combination of avoidance conditioning schedules and increased intake of salt and water results in progressive hypertension in dogs within 14 days. The present experiments investigated the effects of increasing potassium intake upon blood pressure and heart rate of dogs made hypertensive by avoidance conditioning and salt-water loading. Two daily 30-minute sessions of free-operant avoidance conditioning were presented for 36 days during which isotonic saline was continuously infused into the arterial circulation (1.2 liters/day; 185 mEq Na+). Daily mean levels of systolic (22 +/- 5 mm Hg) and diastolic (12 +/- 4 mm Hg) pressure increased progressively in each dog during Days 1-14. Infusion of potassium chloride (100 mEq/day) from Days 15-28 resulted in progressive decreases in daily mean levels of systolic (-11 +/- 2 mm Hg) and diastolic (-8 +/- 1 mm Hg) pressure in each dog over this period. From Day 29-36, systolic (8 +/- 1 mm Hg) and diastolic (5 +/- 1 mm Hg) pressure increased. Normotensive dogs not on the avoidance schedule showed no change in arterial pressure in response to 14 days of potassium chloride infusion. These experiments show that the level of potassium, as well as sodium, intake significantly determines blood pressure levels in this form of experimental hypertension.