Influence of nonhemodynamic factors on the microcirculation in moderate arterial essential hypertension

Relationship between vitamin D3 and the peripheral circulation in moderate arterial primary hypertension

Although altered cellular calcium handling plays a critical role in the pathophysiology of hypertension, little attention has been focused on the impact of calcium regulating hormones on target-organs (e.g. vascular tissue). Therefore the relationship between calcium, phosphorus, parathyroid hormone, 25- and 1,25-(di) hydroxyvitamin D3, blood pressure (BP) and regional circulation was examined in 25 patients (44 +/- 2.5 years) with moderate hypertension (systolic BP 164 +/- 4 mmHg, diastolic BP 105 +/- 2 mmHg). Calf and finger blood flow were measured simultaneously using ECG-triggered plethysmography at rest and after 3 min arterial occlusion (reactive hyperemia). Systolic and diastolic BP were inversely correlated with 25-hydroxyvitamin D3 (r = -0.511 and r = -0.445, p < 0.002). Calf vascular resistance at rest (r = -0.46, p = 0.02) and after 3 min arterial occlusion (r = -0.78, p = 0.0001) was related to 25-hydroxyvitamin D3 concentration. Only calf vascular resistance during reactive hyperemia was significantly related to 1,25-dihydroxyvitamin D3 (r = -0.44, p = 0.03). After correction for blood pressure calf vascular resistance after 3 min arterial occlusion remained significantly and inversely related with 25-hydroxyvitamin D3. There was no relation between finger (skin) circulation and vitamin D3. All other calcium regulating factors were unrelated to the parameters of peripheral circulation. Our results indicate that among the calcium regulating factors, particularly vitamin D3 seems to inversely influence muscle, but not skin vascular tone-independently of blood pressure in mild to moderate hypertension.