CALCIUM-REGULATING HORMONES IN HYPERTENSION - VASCULAR ACTIONS

The vascular and potentially hypertensive actions of the calcium-regulating hormones 1,25-dihydroxycholecalciferol [1,25(OH)2D3], parathyroid hormone (PTH), and calcitonin and related factors such as parathyroid hypertensive factor (PHF) and calcitonin gene-related peptide (CGRP) are discussed. 1,25(OH)2D3 has inotropic and calciotropic actions on isolated vascular tissue whereas PTH is a vasodilator. PHF, which has been reported in plasma of humans with essential hypertension and spontaneously hypertensive rats, has both pressor and calciotropic actions. Calcitonin is without vascular effects and CGRP is a potent vasodilator. It is concluded that several of the hormones responsible for maintaining Ca2+ homeostasis modulate vascular Ca2+ metabolism and force generating capacity. These substances may be long-term modulators of vascular function and play a role in the determination of peripheral vascular resistance.