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This study is aimed at examining the role of non-hemodynamic factors on the impaired microcirculation in patients with moderate essential hypertension. In a series of 31 patients (mean age, 47.8 +/- 1.1 years) with newly diagnosed untreated moderate essential hypertension (mean systolic blood pressure 161.7 +/- 2.0 mm Hg, mean diastolic blood pressure 102.4 +/- 1.5 mm Hg), parameters of the capillaroscopic examination of the finger microcirculation (mean number of capillaries, NRCAP), length of the capillaries (LECAP, microns), diameter micron) of the efferent (EFDI) and afferent (AFDI) apillaries, and mean red blood cell velocity (RBCV, microns/sec), which was measured by the flying spot technique, were correlated with a number of hormones (sampled after an overnight fast) including: plasma renin activity, aldosterone, and parathyroid hormone (PTH). A significant correlation (P less than .05) could be obtained between several parameters of the microcirculation and PTH:PTH (23.8 +/- 1.4 pg/mL)-NRCAP (14.9 +/- 0.5): r = -0.440, P = .013; PTH-AFDI (4.0 +/- 0.5 microns): r = 0.442, P = .012; PTH-EFDI (2.8 +/- 0.5 microns): r = 0.416, P = .019; PTH-RBCV (711 +/- 69 microns/sec): r = -0.351, P = .05. Furthermore, 24-h urinary norepinephrine (U-NOR) and afferent and efferent diameter of the capillaries intercorrelated significantly: U-NOR (46.0 +/- 6.2 micrograms/24 h)-AFDI: r = 0.439, P = .034; U-NOR-EFDI; r = 0.462, P = .025. This study shows that in patients with moderate essential arterial hypertension nonhemodynamic factors have an influence at the level of the microcirculation.

In a randomized double-blind, placebo-controlled, crossover study of isradipine (5 mg twice daily), effects on peripheral hemodynamic reflex responses were studied in nine patients (mean age 48 years) at baseline and after six weeks of active treatment. Assessments included vital signs, resting blood flow in the calf and finger (using an electrocardiograph-triggered venous occlusion plethysmograph), reflex responses during isometric exercise and cold pressor resistance, and venous capacitance in the forearm and calf. Isradipine lowered systolic and diastolic blood pressure as well as mean arterial pressure in patients with mild-to-moderate essential hypertension without reflex tachycardia or venoconstriction. All of the reflex responses studied were attenuated. It is concluded that vasodilatation of the peripheral circulation induced by isradipine contributes partially to the blood pressure-lowering effect.