Sympathetic nerve hyperactivity is associated with increased peripheral vascular resistance in hypopituitary patients with growth hormone deficiency.

Abstract

Hypopituitary patients with untreated GH deficiency have increased cardiovascular mortality. Sustained vasoconstriction is an important factor in the development of hypertension and insulin resistance. This study was designed to see whether peripheral vascular resistance was increased in subjects with GH deficiency and to examine the mechanisms involved. Nine patients with GH deficiency and nine matched control subjects were studied. Calf vascular resistance was measured by venous occlusion plethysmography and sympathetic vasoconstrictor nerve activity by peroneal microneurography. Subjects with GH deficiency had a significantly lower blood flow (by 31%) and higher vascular resistance (by 48%) than the control group. In addition, they had a significantly higher sympathetic vasoconstrictor activity (by 67%) and this correlated with the vascular resistance (r = 0.45; P < 0.04). Patients with GH deficiency have an increased peripheral vascular resistance that is contributed to by an increase in central sympathetic vasoconstrictor discharge to the peripheral vasculature. This could be important in the development of cardiovascular disease in this condition.