Baseline and stimulated catecholamine secretion in normotensive patients with active acromegaly: acute effects of continuous octreotide infusion

Objective: Alterations in catecholamine plasma levels may contribute to the cardiovascular complications of acromegaly. Since few data are available o n the catecholamine secretory dynamics in active acromegaly and no evidence exists on catecholamine variations during GH decrease, we studied acromega lic patients before and during octreotide administration. Methods: Mie evaluated the catecholamine responses to upright posture and a cold pressure test (CPT) in 11 acromegalic (A) patients before and during continuous administration of octreotide (500 mu g/24 h by s.c. pump) compar ed with 11 normal(N) subjects. Results: All the acromegalic patients showed left ventricular cardiac hyper trophy. The cardiovascular responses to upright posture were similar betwee n normal subjects and acromegalics both before and during octreotide treatm ent, The basal levels of norepinephrine (NE) were significantly higher in A patients compared with N subjects (423 +/- 45 vs 264 +/- 32 pg/ml, P < 0.0 5) and decreased during therapy (291 +/- 32 pg/ml: P < 0.01). The increase in plasma NE during upright posture was significantly lower in A than in N subjects (P < 0.01), but was restored to normal during octreotide treatment . CPT increased systolic and diastolic blood pressure, pulse rate and NE pl asma levels in N (P < 0.05) but not in A subjects both before and during oc treotide treatment. Conclusions: Our data demonstrate the presence of increased basal NE levels in acromegalic patients with a defective sympathetic response to stimuli. Short-term octreotide infusion is able to induce a reduction in the basal l evels of NE and a normalization of the catecholamine response to posture.