Nasopulmonary bronchomotor reflexes elicited by mechanical or irritant stimulation of the nose have been described in animals and asthmatic patients. However, few studies were devoted to the consequences of nasal breathing of cold and dry air or of only dry or only moist air on the bronchomotor control in normal individuals. The present study reported changes in interruption resistance (Rint) measured during eupneic breathing of moderately cold (-4 or -10 degrees C) and dry [0.3% relative humidity (RH)] air or of room air at 23 degrees C that is either dry (0.3% RH) or moist (97% RH). Nasal inhalation of cold (-4 degrees C) dry air or of only dry air significantly increased baseline Rint value (17 and 21%, respectively) throughout the 15-min test periods. The response to cold was significantly accentuated when the air temperature was lowered to -10 degrees C (42%). After nasal anesthesia or inhalation of a cholinergic antagonist, cold air did not induce a change in Rint. Nasal inhalation of moist room air had no effect. No Rint changes were measured during oral breathing of the three test agents. It is concluded that the activation of cold receptors or osmoreceptors in the nasal mucosa induces protective bronchoconstrictor responses in normal individuals.

The consequences of chronic hypoxemia on maximal force and endurance time to sustained 80% of maximal isometric contraction of two skeletal muscles (adductor pollicis and vastus lateralis) and the diaphragm were studied in patients with chronic obstructive pulmonary disease (COPD). Compared to normal subjects, COPD patients have lower values of Fmax for the two skeletal muscle groups and Pmax (diaphragm). Endurance time was also shorter for the diaphragm and adductor pollicis. Chronic hypoxemia was associated with an accentuation in integrated EMG changes in both low and high frequency bands for adductor pollicis and diaphragm. Inhalation of oxygen enriched gas mixture for a 15-min period increased markedly Fmax and PImax values, prolonged the endurance time to sustained thumb adduction, and reduced the EMG changes in the low frequency band for adductor pollicis. The present observations provide evidence for altered maximal performances of skeletal muscles in chronic hypoxemic patients and also point out the virtues of oxygen breathing in these patients.

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