ALAE NASI ACTIVATION DECREASES NASAL RESISTANCE DURING HYPEROXIC HYPERCAPNIA

It has been proposed that decreases in nasal resistance (Rn) during hy percapnia are entirely due to vasoconstriction in the nasal cavity. We hypothesized that alae nasi (AN) muscle activity dilates the nasal ve stibule and contributes to the decrease in Rn during hypercapnia. Nine normal subjects were studied during hyperoxic hypercapnia (HH). Rn an d vestibular resistance (Rvest) for one nasal passage were measured si multaneously with the AN electromyogram before and after nasal deconge stion. HH decreased Rvest from 1.6 +/- 0.6 to 0.8 +/- 0.9 cmH(2)O . 1( -1). s (predecongestant) and from 1.3 +/- 0.8 to 0.6 +/- 0.7 cmH(2)O . 1(-1). s (postdecongestant; both P < 0.01). Nasal decongestant decrea sed Rn but not Rvest. Significant inverse linear relationships between Rvest and AN electromyogram were demonstrated for all subjects. We co nclude that in normal subjects during HH 1) decreases in Rvest are pre dominantly due to increases in AN activity; and 2) decreases in Rn are due to a combination of mucosal vasoconstriction and AN activation.