1. Ouabain-sensitive 86Rb uptake was used to assess sodium-potassium pump activity in vascular smooth muscle of animals with various types of experimental hypertension.
2. The findings suggest that pump activity is suppressed in the non-genetic low renin, presumably volume-expanded forms of hypertension.
3. By contrast, pump suppression does not appear to be involved in spontaneously hypertensive rats or in salt-induced hypertension in Dahl's salt-sensitive rats. In these genetic models the primary defect may be increased cell membrane permeability.