[Combined effects of hypoxia and hypercapnia on the functional state of the respiratory center]

Abstract

Experiments were conducted on cats under nembutal anesthesia; a study was made of pulse activity of bulbar respiratory neurons, electrical activity of the diaphragm and of the intercostal muscles; pO2, pCO2, pH, arterial blood oxygen saturation were determined in combined action of hypoxia and hypercapnia. When hypoxic gaseous mixture was given for respiration the developing hypocapnia disturbed the discharge rhythmic activity of the respiratory neurons, the respiration acquiring a pathological character of the Cheyne--Stokes type. After addition to the hypoxic gaseous mixture of 2% CO2 the gaseous composition of the arterial blood approached the initial values; this addition prevented the development of hypercapnia and disturbances of rhythmic discharge activity of the respiratory neurons. Addition of 5% CO2 to the hypoxic gaseous mixture produced a negative effect: at first it intensified and then depressed the pulse activity of the respiratory neurons, caused metabolic and respiratory acidosis, and promoted asphyxia.