The effect of octreotide on breathing and the ventilatory response to CO2 in conscious dogs.

It has been reported that injection of somatostatin into the brain-stem will lead to apnoea in animals. The aim of this study was to determine whether peripheral administration of octreotide, an analogue of somatostatin, could influence the control of breathing. We measured the tidal volume, respiratory rate and ventilatory response to CO2, before and after the intravenous injection of two dose levels of octreotide (0.1 mg and 0.5 mg) or saline in four conscious adult dogs. Injection of octreotide altered the breathing pattern with a mean decrease in the respiratory frequency of 23% (p<0.05) and an increase in the tidal volume by 16% (p<0.05), resulting in no net change in ventilation. The normal value of the ventilatory response to CO2 ranged between 1.0-3.2 L x min(-1) x mmHg(-1), with a minor variance within each dog but a significant difference amongst the four dogs (p<0.05). No significant change in the ventilatory response to CO2 was observed after octreotide. We conclude that intravenous octreotide alters the pattern of breathing but preserves minute ventilation; peripheral administration of octreotide does not influence the ventilatory response to CO2.