Biomaterial Database

Hypercapnia selectively attenuates the somato-sympathetic reflex. 2004

John M Makeham, and A K Goodchild, and N S Costin, and Paul M Pilowsky

Department of Physiology, Hypertension and Stroke Research Laboratory, University of Sydney, NSW, Australia.

The effects of hyperoxic hypercapnia (5, 10 or 15% CO2 in O2) on splanchnic sympathetic nerve activity (sSNA) and sympathetic reflexes such as the somato-sympathetic reflex or baroreflex were studied in urethane anaesthetised, paralysed, artificially ventilated and vagotomized Sprague-Dawley rats. Hypercapnia caused a small increase in mean arterial blood pressure (MAP) in the 10% CO2 group and a fall in heart rate (HR) in all three groups. sSNA increased in all three groups. Phrenic frequency and amplitude increased during hypercapnia, with frequency adapting back towards baseline during the CO2 exposure. The somato-sympathetic reflex was attenuated in the 5% CO2 group and abolished in the 10 and 15% CO2 groups, whereas there was little effect on the sSNA baroreflex. Hypercapnia significantly affects phrenic nerve activity (PNA), sSNA and selectively inhibits the somato-sympathetic reflex with little effect on the sSNA baroreflex.

UI	MeSH Term	Description	Entries
D008297	Male		Males
D010791	Phrenic Nerve	The motor nerve of the diaphragm. The phrenic nerve fibers originate in the cervical spinal column (mostly C4) and travel through the cervical plexus to the diaphragm.	Nerve, Phrenic,Nerves, Phrenic,Phrenic Nerves
D011930	Reaction Time	The time from the onset of a stimulus until a response is observed.	Response Latency,Response Speed,Response Time,Latency, Response,Reaction Times,Response Latencies,Response Times,Speed, Response,Speeds, Response
D012018	Reflex	An involuntary movement or exercise of function in a part, excited in response to a stimulus applied to the periphery and transmitted to the brain or spinal cord.
D001784	Blood Gas Analysis	Measurement of oxygen and carbon dioxide in the blood.	Analysis, Blood Gas,Analyses, Blood Gas,Blood Gas Analyses,Gas Analyses, Blood,Gas Analysis, Blood
D001794	Blood Pressure	PRESSURE of the BLOOD on the ARTERIES and other BLOOD VESSELS.	Systolic Pressure,Diastolic Pressure,Pulse Pressure,Pressure, Blood,Pressure, Diastolic,Pressure, Pulse,Pressure, Systolic,Pressures, Systolic
D002245	Carbon Dioxide	A colorless, odorless gas that can be formed by the body and is necessary for the respiration cycle of plants and animals.	Carbonic Anhydride,Anhydride, Carbonic,Dioxide, Carbon
D004305	Dose-Response Relationship, Drug	The relationship between the dose of an administered drug and the response of the organism to the drug.	Dose Response Relationship, Drug,Dose-Response Relationships, Drug,Drug Dose-Response Relationship,Drug Dose-Response Relationships,Relationship, Drug Dose-Response,Relationships, Drug Dose-Response
D004558	Electric Stimulation	Use of electric potential or currents to elicit biological responses.	Stimulation, Electric,Electrical Stimulation,Electric Stimulations,Electrical Stimulations,Stimulation, Electrical,Stimulations, Electric,Stimulations, Electrical
D004594	Electrophysiology	The study of the generation and behavior of electrical charges in living organisms particularly the nervous system and the effects of electricity on living organisms.