1. In autonomic failure, supine exercise lowers blood pressure and worsens postural hypotension. The somatostatin analogue, octreotide, reduces postprandial and postural hypotension, but its effects on exercise-induced hypotension and on postural hypotension post-exercise are unknown.
2. Eighteen subjects with chronic sympathetic denervation were studied; 12 had pure autonomic failure and six had additional neurological features of the Shy—Drager syndrome. Haemodynamic, hormonal and biochemical changes were measured before, during and after incremental supine leg exercise on two occasions: on no treatment and after subcutaneous octreotide. Exercise was performed 120 min after octreotide in eight subjects and 60 min after octreotide in ten subjects.
3. Octreotide did not improve exercise-induced hypotension; the blood pressure fall was greater during exercise, but the blood pressure level was no different than without treatment. Heart rate, stroke distance, cardiac index and systemic vascular resistance were similar at rest and changed to the same degree with exercise on and off octreotide. After octreotide, resting levels of serum growth hormone, plasma noradrenaline, adrenaline and renin were unchanged, but glucose was higher and insulin was lower. There was no change in biochemical and hormone levels during exercise either off or on octreotide.
4. After octreotide, although the rate of blood pressure recovery was similar post-exercise, the levels of blood pressure were higher than in the non-treatment phase and postural hypotension was improved before and after exercise.
5. In conclusion, in primary autonomic failure, octreotide did not improve exercise-induced hypotension in the supine position, suggesting that octreotide-sensitive vasodilatory peptides do not contribute to the blood pressure fall. With octreotide, supine blood pressure levels were higher post-exercise and postural hypotension was improved both before and after exercise.
