Impairment Of Sympathetic Innervation Research Articles

Streptozotocin-induced diabetes reduces the density of sympathetic innervation and increases adrenosensitivity of small renal arteries in rats

Autonomic neuropathy is a common complication of diabetes mellitus, but impairment of sympathetic innervation appears differently in different vascular beds. According our data, intermediate-stage (6-week) diabetes reduces the density of periarterial nerve plexus in small renal arteries by 30%. The aim of this study was to test the hypothesis that such partial denervation affects adrenosensitivity of renal arteries from diabetic rats and to explore the possible mechanisms.

Advances in Imaging of the Cardiac Neuronal System

Left ventricular ejection fraction (LVEF) is a useful tool for stratifying risk for heart failure progression and life-threatening arrhythmic events. Yet, the clinical course of heart failure patients with severely reduced LVEF is variable, and the majority of patients who die suddenly do not have an LVEF ≤35%. A recently completed large multicenter trial, ADMIRE-HF, confirms that cardiac neuronal imaging with I-123 metaiodobenzylguanidine is an important independent predictor of heart failure progression and sudden cardiac death. Data from that study indicate that heart failure patients with severe impairment of cardiac sympathetic innervation are at highest risk for heart failure progression, heart failure patients with moderate impairment of sympathetic innervation are at highest risk for life-threatening arrhythmic events, and heart failure patients with preserved sympathetic innervation are at low risk for either death due to heart failure progression or sudden cardiac death.

Increase in the sensitivity of the vascular smooth muscle to constrictor factors after denervation and with a decrease in blood pressure

The effect of denervation on the contractile activity of the saphenous artery in normotensive rats and rats with regional hypotension was studied. Hypotension was caused by partial occlusion of the abdominal aorta distally from the renal arteries, and then, in four weeks, to denervate the saphenous artery, a portion of the femoral nerve in one of the limbs was resected. In two more weeks, the contractile responses of ring preparations of the saphenous artery (after removal of the endothelium and block of neuronal uptake and β-adrenoreceptors) were investigated under isometric conditions. In normotensive rats, the denervation led to an increase in the vascular sensitivity to norepinephrine, phenylephrine, serotonin, and KCl. Similar changes in contraction were caused by chronic hypotension; however, rats with hypotension exhibited no additional denervation-induced increase in the vascular sensitivity. After treatment with glyoxylic acid, the fluorescence intensity of the vascular adrenergic fibers adapted to a reduced pressure was lower than that in the norm. It was assumed that the vascular hypersensitivity in hypotension is caused by impairment of sympathetic innervation.

Impact of sympathetic innervation on recurrent life-threatening arrhythmias in the follow-up of patients with idiopathic ventricular fibrillation

Idiopathic ventricular fibrillation (IVF) is defined as VF in the absence of any identifiable structural or functional cardiac disease. The underlying pathophysiological mechanisms are unknown. This study was performed to investigate the potential impact of sympathetic dysfunction, assessed by (123)I-meta-iodo-benzylguanidine scintigraphy ((123)I-MIBG SPECT), on the long-term prognosis of patients with IVF. (123)I-MIBG SPECT was performed in 20 patients (mean age 37+/-13 years) with IVF. Mean follow-up of patients after study entry was 7.2+/-1.5 years (range 4.9-10.5 years). Ten patients (five men, five women; mean age 43+/-12 years; p=NS versus study group) with medullary carcinoma of the thyroid gland served as an age-matched control group. Abnormal (123)I-MIBG uptake was observed in 13 patients (65%). During follow-up, 18 episodes of VF/fast polymorphic ventricular tachycardias occurred in four IVF patients with abnormal (123)I-MIBG uptake whereas only two episodes of monomorphic ventricular tachycardia (and no VF) occurred in a single IVF patient with normal (123)I-MIBG uptake. Impairment of sympathetic innervation may indicate a higher risk of future recurrent episodes of life-threatening ventricular tachyarrhythmias in patients with IVF. Studies in larger cohorts are required to validate the significance of (123)I-MIBG SPECT during the long-term follow-up of these patients.

Delayed local depolarisation and repolarization in postinfarction patients caused by impairment of sympathetic innervation

Delayed local depolarisation and repolarization in postinfarction patients caused by impairment of sympathetic innervation