"The sympathetic ganglion is not a simple relay station but a site modulated by short inter-neurons and a variety of neurotransmitters and receptors. Therefore, [T2-T3] ETS might have modified the sympathetic regulation of adrenaline secretion from the adrenal medulla. [T2-T3] ETS increases the plasma level of atrial natriuretic peptide, which has widespread sympatholytic activity. [T2-T3] ETS might have influenced the amount of adrenaline secreted from the adrenal medulla via changes in humoral factors such as atrial natriuretic peptide."(Nakamura 2002)
Stroke index and systemic vascular resistance were similar both at rest and at submaximal exercise before and after ETS. Thus, ETS reduces myocardial oxygen demand and plasma noradrenaline levels both at rest and during exercise without significantly depressing cardiac function in terms of stroke volume.
http://www.ncbi.nlm.nih.gov/pubmed/11954949?dopt=Abstract