EFFECTS OF A NARCOTIC LEVEL OF CARBON DIOXIDE ON THE PLASMA POTASSIUM AND RESPIRATION OF CATS

Abstract

Normal anesthetized cats breathing 34% CO2 in O2 showed a rapid rise in plasma K, reaching a peak in 5 1/2 mins. and then gradually returning to near normal in about 30 mins., while the CO2 was being continued. Adrenalectomized cats breathing high CO2 showed a similar but smaller rise, suggesting the participation of the adrenal-hepatic mechanism in the CO2 effect, but indicating that another mechanism must also be involved. Eviscerated cats on high CO2 showed no rise in plasma K. On the removal of CO2 normal, adrenalectomized and eviscerated cats showed a small rise in plasma K, probably released from the muscles to maintain the acid-base balance. In all the cats, the high CO2 caused an initial stimulation of respiration, followed by a sudden depression as the CO2 passed from the excitatory to the narcotic level. The height of the stimulation and the depth of the depression usually occurred within about 5 mins. on CO2. Thereafter, the respiration gradually increased, approaching the stimulation peak value in the case of the normal cats. Neither adrenalectomized nor eviscerated cats showed such a remarkable increase in respirations, as measured by min. vol. after the depression, though the adrenalectomized cats did show a very large increase in tidal vol.