Iron deficient cardiac hypertrophy is not unique in this regard, as Lin has recently documented enhanced contractility without increased heart rate in hyper-sympathetic transgenic mice [ 34].
The lateralized (right) increased mesiotemporal grey matter volume in our cohort may contribute to chronic, asymmetric hyper-sympathetic activation, or a sympathetic system lacking in appropriate responsiveness, which would contribute to mechanisms that pose a risk for sudden death.
Therefore, migraine attacks seem to occur as a consequence of the imbalance between the brain stem projections upon the intrinsic noradrenergic system and frontal regulatory executive mechanisms resulting in sensory and sympathetic hyper-activation [26].
35– 38 Our results, however, show that in the elderly, sympathetic hyper-activation occurs in the moments after exercise.
Hyper-responsivity of sympathetic nervous activity may also constitute a risk factor for the development or progression of CVD [ 36].
Discontinuation of beta-blocker therapy is indeed associated with a "withdrawal syndrome", a transient sympathetic hyper-response caused by hypersensitivity of cardiac β-receptors [ 18].
The association between endothelial function and frailty might be due to the sympathetic hyper-activation of CKD [ 29], generating an autonomous dysfunction and, consequently, a reduction of vascular perfusion in the skeletal muscle.
By utilizing a hyper-sensitive response to sympathetic stimulation, coupled with an unchanged or lower heart rate, the iron deficient heart can potentially offset some of the oxygen delivery deficiencies of anemic blood without risking myocardial ischemia.
If the inhibitory stimulus is abruptly removed, a set of symptoms including central nervous stimulation (e.g., agitation, irritability, tremors, increased wakefulness), sympathetic nervous system hyper-activation (e.g., fever, hypertension, tachycardia, tachypnea, sweating) and gastrointestinal disturbance (e.g., vomiting, nausea, diarrhea) can occur.
Marriage may reduce stress and stress related illness [ 22], by attenuating the effects of stress on cardiovascular hyper-reactivity and on exaggerated sympathetic nervous system activity [ 71].
Under sedation can cause hyper-catabolism, immunosupporession, hypercoagulability and increase sympathetic activity.
