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Flow resistance and its components in hypertensive men treated with the calcium antagonist isradipine
M Wysocki1, B Persson, U Bagge
1Department of Medicine I, Sahlgrenska Hospital, University of Göteborg, Sweden.
Insights
Isradipine, a calcium antagonist, effectively lowers blood pressure in hypertensive men by reducing vascular resistance in arteries. This treatment improves arterial compliance without affecting blood viscosity or venous compliance.
Area of Science:
- Cardiovascular Pharmacology
- Hypertension Research
- Hemodynamics
Background:
- Essential hypertension is characterized by elevated blood pressure.
- Understanding blood flow resistance components is crucial for managing hypertension.
- Dihydropyridine calcium antagonists are used to treat hypertension.
Purpose of the Study:
- To investigate the effects of isradipine on blood flow resistance components in men with essential hypertension.
- To determine how isradipine modulates vascular resistance, arterial compliance, and hemorheological parameters.
Main Methods:
- A study involving 14 men with essential hypertension (diastolic blood pressure ≥ 100 mm Hg).
- Measurements taken before and after treatment with the calcium antagonist isradipine.
- Assessment of total and renal vascular hindrance, blood viscosity, and arterial/venous compliance.
Main Results:
- Isradipine significantly reduced total and renal vascular hindrance.
- Arterial compliance was increased by isradipine, while venous compliance remained unchanged.
- Blood viscosity was unaffected, but the pressor response to phenylephrine decreased.
Conclusions:
- The antihypertensive effect of isradipine is attributed to functional modulation of small and large arteries.
- Isradipine treatment improved arterial compliance and reduced vascular resistance.
- Blood flow properties and venous system compliance were not significantly affected by isradipine.
Abstract:
The components of blood flow resistance were investigated in 14 men with essential hypertension (diastolic blood pressure higher or equal to 100 mm Hg) before and after treatment with the dihydropyridine calcium antagonist-isradipine. Isradipine reduced intraarterial blood pressure by decreasing the total (placebo 5.1 U.mPa-1.s-1; isradipine 3.9 U.mPa-1.s-1), and renal (placebo 48.9 U.mPa-1.s-1, isradipine 35.4 U.mPa-1.s-1) vascular hindrance, the blood viscosity being unchanged. Arterial compliance was increased by isradipine (placebo 1.03 ml.mmHg-1; isradipine 1,25 ml.mmHg-1). The pressor response to adrenergic alpha stimulation with phenylephrine was decreased during treatment with the calcium antagonist. The compliance of the venous system was not changed by the treatment with isradipine. Haemorheological parameters were stable throughout the study but some changes in the correlations between the different rheological parameters were observed. The present study indicates that the antihypertensive effect of the dihydropyridine calcium antagonist isradipine was the result of functional modulation of the small and large arteries, the venous system and the flow properties of blood being unaffected.