The GP.Mur red cell phenotype (higher band 3 expression) affects respiratory frequency and the inspiratory/expiratory ratio in a breath cycle during exhaustive exercise

Abstract

The GP.Mur red cell phenotype is characterized by the unique presence of glycophorin B-A-B hybrid protein on the erythrocyte membrane which promotes band 3 expression. Band 3, or anion exchanger-1, transports HCO3 - across the erythrocyte membrane by exchange of Cl-; this function of band 3 works in concert with intraerythrocytic carbonic anhydrase II (CAII) to facilitate blood CO2 transport. People with the GP.Mur blood type express 10-20% more band 3 protein than those without the special blood type. We thus hypothesized that respiration in people with the GP.Mur blood type might be distinctly different when being challenged. In this study, we recruited 36 age-matched male elite athletes (13 GP.Mur and 23 without GP.Mur [control]) for an incremental running test to exhaustion. While running on a treadmill, the subjects were continuously monitored using a Quark CPET (cardiopulmonary exercise testing) unit (COSMED, Italy). Two statistical methods were employed for data analysis: (1) unpaired t-test for comparison at individual timepoints; and (2) linear mixed modeling for serial cardiopulmonary measurements collected during the running test. We found that their running abilities were similar. However, the subjects with GP.Mur showed higher respiratory rates and smaller inspiratory/expiratory (I/E) ratios than the control subjects throughout the entire exhaustive running test. That is, GP.Mur+ subjects spent a larger fraction of the respiratory cycle time on CO2 excretion than inspiration; their respiration also appeared to respond faster to the same level of workload. These resulted in lower end-tidal CO2 pressure in the running GP.Mur subjects compared to the controls. In conclusion, we presented direct evidence that band 3-mediated HCO3 -/CO2 exchange at the erythrocyte level could impact the respiratory pattern of CO2 excretion. Taiwan National Science and Technology Council; MacKay Memorial Hospital This is the full abstract presented at the American Physiology Summit 2023 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.