Human G protein β3 subunit variant does not alter hypercarbic or hypoxic ventilatory response

Hypercarbic respiratory drive is mainly determined by P_CO2 and pH with activity of the intracellular Na⁺/H⁺ exchanger (NHE) playing an important role in maintaining intracellular pH and respiratory drive. Because NHE activity varies with genetically different G‐protein β3 subunits (GNB3) (C/T polymorphism at nucleotide position 825) different genotypes might alter respiratory regulation. To test the hypothesis that short‐term ventilatory responses vary with different GNB3 healthy volunteers with different genotypes (CC, TC, TT) were exposed to either hyperoxic hypercarbia (n=33) or to isocapnic hypoxia (n=31), respectively. There was no difference between CC, TC, and TT genotypes in hypercarbic and hypoxic respiratory drive when assessed as the ratio of minute ventilation over endexpiratory P_CO2 changes (ΔV˙E /ΔPET _CO2), maximal tolerable PET _CO2, and ratio of changes in ventilation over arterial haemoglobin desaturation (ΔV˙_E/ΔS_O2), respectively. Thus, short‐term hypercarbic and hypoxic ventilatory drive do not differ between individuals with genotypes encoding different GNB3. Whilst respiratory control may still be influenced by G‐protein aberration, other mechanisms seem to have a more important role in controlling ventilation.