Somatostatin-induced apnea: interaction with hypoxia and hypercapnea in the rat.

The effects of hypoxia and hypercapnea in the production of somatostatin (SRIF)-induced apnea were studied during rebreathing experiments. Hypoxia and hypercapnea resulted in a shortening of the latency of SRIF-induced apnea. In order to exclude the effect of stimulation of central chemoreceptors by mock-CSF solution, control experiments using mock-CSF in combination with hypoxia and hypercapnea were done. No apnea could be produced by the mock-CSF in combination with hypoxia and hypercapnea. The shortening of apneic latency from 480 +/- 8 s (S.E.M.) to 148 +/- 30 s with the addition of a chemostimulus (hypoxia and hypercapnea) in SRIF-induced respiratory depression demonstrates that chemostimulation interacts with the centrally originating apnea to enhance its apneic response.