Effects of respiratory stimulation on alae nasi electromyograms and respiratory changes in length in dogs.

The relationship between the electrical and mechanical activity of the nasal dilator muscle was assessed in 8 pentobarbital-anesthetized, tracheostomized, supine dogs. Alae nasi electromyograms (EMGs) were recorded with bipolar fine wire electrodes, and respiratory changes in muscle length were recorded contralaterally using sonomicrometry. During both resting and stimulated breathing, the intrabreath pattern of muscle shortening closely paralleled the intrabreath pattern of EMG activity. Increases in both alae nasi EMG and alae nasi inspiratory shortening occurred in response to single-breath airway occlusions, brief periods of asphyxia, progressive hyperoxic hypercapnia, and intravenous nicotine sulfate administration. With all interventions, the increases in mechanical activation of the alae nasi paralleled the increases in alae nasi electrical activity. These results indicate that alae nasi EMGs, closely reflect respiratory changes in alae nasi length under conditions in which no mechanical load is placed in the nasal muscle.