Biomaterial Database

CO2-H+ stimuli and neural muscular drive to ventilation during dynamic exercise: comparison of stimuli at constant levels of ventilation. 1983

D Essfeld, and J Stegemann

In exercising man, the ventilatory responses to CO2-H+ stimuli and neural muscular drives were compared at constant ventilation (VE). For that purpose, a small increase of the CO2-H+ stimulus in exercise was to be counterbalanced by work load reductions in such a way that the magnitude of ventilation remained unchanged. Control of end-tidal PO2 and PCO2 (PETO2, PETCO2) was established to minimize the influence of changed mixed venous gas tensions on the arterial levels. Only in metabolic acidosis could the additional CO2 stimulus be compensated by work load reduction. This compensation was due to the concomitant decrease of acidosis. Below the 2 mmol X l-1 [La]a threshold, decrements of work load, VO2, and VCO2 showed no effect on VE, when PETCO2 and PETO2 were regulated at constant levels. After the termination of end-tidal clamps, the proportional relation of VE to VO2, VCO2, and work load was largely reestablished. The results show that neural muscular drives cannot decrease ventilation against a background of constant arterial feedback stimuli. Transient decreases of the CO2-H+ stimulus seem to be necessary to readjust the ventilation to a decreased CO2 flow to the lungs. It is suggested that the overall effect of decreasing CO2 is to inhibit the respiratory centers and that positive ventilatory effects of CO2 are the result of a disinhibitory influence.

UI	MeSH Term	Description	Entries
D008297	Male		Males
D009469	Neuromuscular Junction	The synapse between a neuron and a muscle.	Myoneural Junction,Nerve-Muscle Preparation,Junction, Myoneural,Junction, Neuromuscular,Junctions, Myoneural,Junctions, Neuromuscular,Myoneural Junctions,Nerve Muscle Preparation,Nerve-Muscle Preparations,Neuromuscular Junctions,Preparation, Nerve-Muscle,Preparations, Nerve-Muscle
D010101	Oxygen Consumption	The rate at which oxygen is used by a tissue; microliters of oxygen STPD used per milligram of tissue per hour; the rate at which oxygen enters the blood from alveolar gas, equal in the steady state to the consumption of oxygen by tissue metabolism throughout the body. (Stedman, 25th ed, p346)	Consumption, Oxygen,Consumptions, Oxygen,Oxygen Consumptions
D010313	Partial Pressure	The pressure that would be exerted by one component of a mixture of gases if it were present alone in a container. (From McGraw-Hill Dictionary of Scientific and Technical Terms, 6th ed)	Partial Pressures,Pressure, Partial,Pressures, Partial
D011659	Pulmonary Gas Exchange	The exchange of OXYGEN and CARBON DIOXIDE between alveolar air and pulmonary capillary blood that occurs across the BLOOD-AIR BARRIER.	Exchange, Pulmonary Gas,Gas Exchange, Pulmonary
D012119	Respiration	The act of breathing with the LUNGS, consisting of INHALATION, or the taking into the lungs of the ambient air, and of EXHALATION, or the expelling of the modified air which contains more CARBON DIOXIDE than the air taken in (Blakiston's Gould Medical Dictionary, 4th ed.). This does not include tissue respiration (	Breathing
D012125	Respiratory Center	Part of the brain located in the MEDULLA OBLONGATA and PONS. It receives neural, chemical and hormonal signals, and controls the rate and depth of respiratory movements of the DIAPHRAGM and other respiratory muscles.	Center, Respiratory,Centers, Respiratory,Respiratory Centers
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
D005082	Physical Exertion	Expenditure of energy during PHYSICAL ACTIVITY. Intensity of exertion may be measured by rate of OXYGEN CONSUMPTION; HEAT produced, or HEART RATE. Perceived exertion, a psychological measure of exertion, is included.	Physical Effort,Effort, Physical,Efforts, Physical,Exertion, Physical,Exertions, Physical,Physical Efforts,Physical Exertions
D006339	Heart Rate	The number of times the HEART VENTRICLES contract per unit of time, usually per minute.	Cardiac Rate,Chronotropism, Cardiac,Heart Rate Control,Heartbeat,Pulse Rate,Cardiac Chronotropy,Cardiac Chronotropism,Cardiac Rates,Chronotropy, Cardiac,Control, Heart Rate,Heart Rates,Heartbeats,Pulse Rates,Rate Control, Heart,Rate, Cardiac,Rate, Heart,Rate, Pulse