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Nisoldipine. Central haemodynamics at rest and during exercise in essential hypertension: acute and chronic studies
P Omvik1, P Lund-Johansen, H Haugland
1Medical Department, Haukeland Hospital, Bergen, Norway.
Insights
Nisoldipine effectively lowers blood pressure by reducing total peripheral resistance in patients with essential hypertension. Long-term treatment diminishes initial reflex increases in heart rate and cardiac output.
Area of Science:
- Cardiovascular Pharmacology
- Hypertension Research
- Clinical Hemodynamics
Background:
- Calcium channel blockers can decrease vascular smooth muscle and myocardial contractility.
- Potential mechanisms for blood pressure reduction include decreased total peripheral resistance (TPR) and cardiac output (CO).
Purpose of the Study:
- To investigate the acute and chronic hemodynamic effects of nisoldipine in patients with essential hypertension.
- To determine if cardiac output is compromised by acute and chronic calcium blockade.
Main Methods:
- Nineteen patients with essential hypertension were studied at rest and during exercise.
- Hemodynamic parameters including intra-arterial pressure, CO, stroke volume, heart rate, and TPR were measured after acute (10 mg) and chronic (1 year, 25 mg) nisoldipine administration.
Main Results:
- Acutely, nisoldipine caused a rapid fall in blood pressure and TPR with a reflex increase in heart rate and CO.
- After 1 year, blood pressure was significantly reduced at rest and during exercise due to decreased TPR; initial reflex tachycardia and increased CO were absent.
Conclusions:
- Nisoldipine lowers blood pressure by reducing TPR both acutely and chronically.
- Long-term nisoldipine treatment leads to a stable hemodynamic profile, likely due to baroreceptor resetting, without compromising cardiac output.
Abstract:
Calcium blockers may reduce contractility of vascular smooth muscle as well as that of myocardial cells. Therefore, falls in both total peripheral vascular resistance (TPR) and cardiac output (CO) might be responsible for a fall in blood pressure (BP) caused by calcium blockers in essential hypertension. We have studied the acute and chronic haemodynamic effects of nisoldipine (a new calcium blocker) in 19 patients with essential hypertension at rest in the supine and sitting positions and during 100-W dynamic exercise to investigate whether CO might be compromised by acute and chronic calcium blockade. Intra-arterial pressure, CO (by Cardiogreen), stroke volume, heart rate and TPR were measured hourly after the first dose of 10 mg nisoldipine (acute study) and then after 1 year of nisoldipine treatment (mean dose 25 mg; chronic study). The maximal first dose response was seen after 1 h, i.e. a fall in intra-arterial pressure (9%) and TPR (19%) and a reflex rise in heart rate (9%) and CO (12%). The effects levelled off during the next 2 h. After 1 year of treatment there was a more marked reduction in BP: at rest intra-arterial pressure fell (14% supine, 16% sitting) due to fall in TPR (19%) but without significant changes in heart rate or CO; during 100-W exercise, intra-arterial pressure fell (14%) due to reduction in both TPR (7%) and CO (6%). In conclusion, nisoldipine lowers BP by reducing TPR, both acutely and chronically. The initial reflex tachycardia and rise in CO disappear during long-term treatment, probably due to resetting of the baroreceptors.(ABSTRACT TRUNCATED AT 250 WORDS)