Cardiovascular responses to upright tilting in hypertensive patients, with and without renal impairment and before and following nisoldipine treatment.

1. Cardiovascular responses to upright tilting were determined before and after treatment with the calcium antagonist, nisoldipine, in patients with essential hypertension and in patients of similar ages and similar degrees of hypertension complicated by renal impairment. 2. Cardiac output was determined by a single breath respiratory method and heart rate and blood pressure by an automatic sphygmomanometer. 3. During placebo treatment, the supine values of heart rate and blood pressure were similar in the two groups, but the renal patients had significantly higher cardiac outputs. Following nisoldipine treatment blood pressure was lower in both groups due to decreased vascular resistance; cardiac output was unchanged. 4. Upright tilting lowered cardiac output in both groups, but the fall in the patients with renal disease was greater. There were similar increases in heart rate, diastolic blood pressure and vascular resistance in both groups. After nisoldipine, in the renal patients the fall in cardiac output was again greater and there was also a fall in systolic blood pressure. 5. These results indicate that patients with hypertension complicated by renal impairment may have reduced orthostatic tolerance particularly after treatment with nisoldipine.