Effects of greater erythroid Cl⁻/HCO₃⁻ transporter (band 3) expression on ventilation and gas exchange during exhaustive exercise

Abstract

Band 3 protein is a Cl-/HCO3- transporter on the red blood cell (RBC) surface with an important role in CO2 excretion. Greater band 3 expression by roughly 20% is found in people with the GP.Mur blood type. Intriguingly, a disproportional percentage of those with GP.Mur excel in field-and-track sports. Could higher band 3 activity benefit an individual's physical performance? This study explored the impact of GP.Mur/higher band 3 expression on ventilation and gas exchange during exhaustive exercise. We recruited 36 nonsmoking, elite male athletes (36.1% GP.Mur) from top sports universities to perform incremental exhaustive treadmill cardiopulmonary exercise testing (CPET). We analyzed CPET data with respect to absolute running time and to individual's % running time and % maximal O2 uptake. We found persistently higher respiratory frequencies and slightly lower tidal volume in GP.Mur athletes, resulting in a slightly larger increase of ventilation as the workload intensified. The expiratory duty cycle (Te/Ttot) was persistently longer and inspiratory duty cycle (Ti/Ttot) persistently shorter for GP.Mur subjects throughout the run. Consequently, PETCO2 (a surrogate marker for alveolar and arterial CO2 tension--PACO2 and PaCO2) was lower in the GP.Mur athletes during the early stages of exercise. In conclusion, athletes with GP.Mur and higher band 3 expression hyperventilate more during exercise in a pattern that utilizes a greater fraction of time for expiration than inspiration to increase the rate of CO2 excretion than increased tidal volume. This greater ventilation response reduced pCO2 and may help to extend exercise capacity in high-level sports.

Erythroid anion transport, nitric oxide, and blood pressure

“…Similar to the finding that GP.Mur increases erythroid HCO 3 − permeability and respiratory excretion of CO 2 (Hsu et al, 2009;Hsu et al, 2015;Hsu et al, 2023), here, we proposed that GP.Mur also increases erythroid NO 3 − /NO 2 − permeability to accelerate erythrocyte processing of NO metabolites, which affects blood pressure (Patel et al, 2011) (Figure 1D). Could the two distinct anion transport modes of AE1 be coupled and AE1 serve as a coordinator for the seemingly separate physiological processes?…”

“…Could the two distinct anion transport modes of AE1 be coupled and AE1 serve as a coordinator for the seemingly separate physiological processes? A recently emerged clue is that GP.Mur+ carriers tend to rely more on aerobic respiration during intense exercise ( Hsu et al, 2023 ). As intense physical activities demand more O 2 delivery and blood flow, conceivably intravascular NO is metabolized and dissipated faster.…”

“…From the respiratory/exercise physiology studies conducted on healthy adults and professional athletes, we repeatedly observed a slightly but statistically significant higher systolic blood pressure (SBP) among those carrying the GP.Mur blood type (Hsu et al, 2015;Chen et al, 2022;Hsu et al, 2023). For verification, we collaborated with one of our health check-up centers located in Eastern Taiwan, where the GP.Mur+ population is four times higher than that in other regions of Taiwan (Chen et al, 2022).…”