Exemplary methods are described for providing responsive vascular control with or without cardiac pacing. An implantable device with responsive vascular and cardiac controllers interprets physiological conditions and responds with an appropriate degree of vascular therapy applied as electrical pulses to a sympathetic nerve. In one implementation, an implantable device is programmed to deliver the vascular therapy in response to low blood pressure or orthostatic hypotension. The device may stimulate the greater splanchnic nerve, to effect therapeutic vasoconstriction. The vascular therapy is dynamically adjusted as the condition improves. In one implementation to benefit impaired physical mobility, vascular therapy comprises vasoconstriction and is timed to coincide with a recurring segment of the cardiac cycle. The vasoconstriction assists circulation and venous return in the lower limbs of inactive and bedridden individuals. In various implementations, cardiac pacing therapy that is synergistic with the vascular therapy may be added to augment treatment.