Alpha-methyldopa selectively reduces alae nasi activity.
1. Sedatives such as the benzodiazepines and alcohol reduce upper airway muscle activity. We hypothesized that a sedating antihypertensive, alpha-methyldopa, might have similar effects. To investigate this hypothesis we studied the effect of alpha-methyldopa on alae nasi electromyographic (EMG) activity during hypercapnia. 2. We studied ten healthy subjects and three subjects with obstructive sleep apnoea during CO2-stimulated breathing. In a preliminary study four subjects demonstrated a fall in alae nasi EMG activity 4 h after the ingestion of 500 mg of alpha-methyldopa during CO2 rebreathing. 3. In six additional normal subjects and three subjects with obstructive sleep apnoea, we studied the alae nasi EMG activity during steady-state hypercapnia with PCO2 held constant 5 torr (0.7 kPa) above baseline. On 2 separate days we studied subjects before and 2 h after they had ingested 750 mg of alpha-methyldopa or placebo. 4. In the normal subjects the mean alae nasi EMG activity fell by 34% 2 h after ingestion of alpha-methyldopa (P less than 0.05) without a change in other ventilatory parameters. 5. In the sleep apnoea group the individual mean alae nasi EMG activity fell 16-49%, with ventilation and tidal volume falling in one patient. 6. We conclude that alpha-methyldopa selectively reduces upper airway motor activity.
Lahive
K C
KC
Charles A. Dana Research Institute, Beth Israel Hospital, Boston, Massachusetts 02215.
Weiss
J W
JW
Weinberger
S E
SE
D000293:Adolescent; D000328:Adult; D004576:Electromyography; D005260:Female; D006801:Humans; D008297:Male; D008750:Methyldopa / Q000494:pharmacology*; D008875:Middle Aged; D009132:Muscles / Q000187:drug effects* / Q000503:physiopathology; D009666:Nose / Q000187:drug effects* / Q000503:physiopathology; D012119:Respiration / Q000187:drug effects; D012891:Sleep Apnea Syndromes / Q000503:physiopathology*
D008750:Methyldopa