Ventilatory regulation of arterial H(+) (pH) during exercise
Karlman Wasserman1, Timothy A Cox1, Kathy E Sietsema1
1Division of Respiratory and Critical Care, Physiology and Medicine, Los Angeles Biomedical Research Institute, Harbor-UCLA Medical Center, David Geffen School of Medicine, University of California at Los Angeles, Torrance, CA 90502, United States.
Abstract:
We hypothesized that exercise ventilation and arterial H(+) ([H(+)]a) are mutually interactive, [H(+)]a stimulating V(E) and V(E) regulating [H(+)]a increase. Fifty-five patients were studied, 10 normal and 45 with cardio-respiratory disorders. Each patient underwent cardiopulmonary exercise testing with simultaneous serial arterial blood gas and pH measurements. Subsequently, they were classified into one of 7 clinical groups: (1) normal, (2) exercise-induced hypoxemia (PaO2<50mmHg), (3) exercise-induced myocardial ischemia, (4) heart failure, (5) COPD, (6) interstitial lung disease, and (7) pulmonary vasculopathy. The average resting pHa was 7.42 or 7.43 for each group. At anaerobic (lactic acidosis) threshold (AT), [H(+)]a increased due to PaCO2 increase (+2mmHg), primarily. At peak exercise, [H(+)]a increased further due to arterial HCO3(-) decrease. In summary, [H(+)]a appears to be closely regulated at rest to AT and further to peak exercise by CO2 elimination from the venous return. No evidence was observed for over-ventilation of CO2, causing the arterial blood to become more alkaline during exercise in the patient groups studied.
Related Concept Videos
Respiratory Regulation of Acid-Base Balance
When carbon dioxide levels increase in the blood, more H+ and HCO3⁻ are...
Chemical Factors Affecting Respiration Centers
CO2 has a potent influence on respiration and is strictly regulated....
Hyperpnea and Hyperventilation
pH Homeostasis
Respiratory...
Physiological Control of Respiration
Breathing, a seemingly passive process, is regulated by the respiratory center in the brainstem. This center coordinates the involuntary control of respirations, which means it occurs without conscious effort, ensuring a smooth and uninterrupted pattern.
Regulation of Ventilation
The body maintains ventilation by monitoring levels of carbon dioxide (CO2), oxygen (O2), and hydrogen ion concentration (pH) in the arterial blood. Among these factors, the level of CO2 plays a crucial...
Compensation Mechanisms
Respiratory Compensation
This mechanism addresses metabolic-induced pH imbalances by adjusting breathing rates. Respiratory compensation begins within minutes of detecting a pH...


