Objective: The somatotropic axis (Growth hormone (GH)/ serum insulin-like growth factor (IGF)-1) has been shown to be of importance for the development of vascular risk factors in adults. We have evaluated sympathetic nerve activity in conditions with a wide range of GH/IGF-I levels and shown that low level of GH/IGF-I is coupled to high sympathetic nerve traffic. Acromegaly, a condition characterised by excessive GH/IGF-I level, is associated with insulin resistance, hypertension and vascular morbidity and mortality all factors known to be related with high sympathetic activity. Against this background the objective of the present study was to evaluate sympathetic outflow in patients with acromegaly.

Design and Method: In a longitudinal prospective study direct recordings of sympathetic nerve activity to the muscle vascular bed (MSA) and cardiovascular, hormonal and biochemical features were attained in 10 patients with Acromegaly prior to and following 1 year of curative surgery.

Results: Sympathetic nerve activity in patients with Acromegaly remained unchanged prior to and following 1 year of curative surgery and did not deviate from matched healthy controls (36 and 31 vs. 33 bursts per minute, 48 and 45 vs. 54 bursts per 100 heart beats, respectively).

Conclusions: These results are in line with our former findings of an inverse relationship between serum IGF-I level and sympathetic outflow and strengthening our hypothesis of the somatotropic axis being tonically involved in the regulation of central sympathetic outflow.