The Effect of Central Chemoreceptors on the Peripheral Respiratory Chemoreflex Response to Hypoxia in Humans

Nasimi A. Guluzade, Western University

Abstract

We measured the peripheral chemoreflex sensitivity to hypoxia (PChS) at various isocapnic carbon dioxide tensions (PCO₂) to determine the form of the relationship between PChS and central PCO₂. Twenty participants completed three repetitions of modified rebreathing tests with end-tidal PO₂ (P_ETO₂) clamped at 150, 70, 60, and 45 mmHg. PChS was computed at 1-mmHg intervals of P_ETCO₂ as follows: the differences in V̇_E between the three hypoxic profiles and the hyperoxic profile (∆V̇_E) were calculated; three ∆V̇_E values were plotted against corresponding calculated oxyhemoglobin saturation (S_CO₂); and linear regression determined PChS (L^∙min^-1∙mmHg^-1∙%S_CO₂^-1). These processing steps were repeated at each P_ETCO₂ to produce the PChS vs. isocapnic PCO₂ relationship which was fitted with linear and polynomial functions. Chemoreflex sensitivity (V̇_ES) rose (PCO₂ fell progressively (pETCO₂ and this relationship was best described by a liner model in 15 of the 20 individuals, indicative of an additive interaction.