SENSITIVITY OF SKELETAL MUSCLE TO INTRA-ARTERIAL ACETYLCHOLINE IN NORMAL AND MYASTHENIC MAN

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Abstract
Acetylcholine rapidly injd. into the brachial artery at the elbow elicits contractions in the muscles of the forearm and hand. The threshold doses range between 0.1 and 1 mg. Five patients with myasthenia gravis did not differ from 5 normal subjects with respect to the character of these contractions or the range of threshold doses of acetylcholine. Acetylcholine rapidly injd. into the radial artery at the wrist elicits contractions of the opposing muscle of the thumb. The threshold doses range between 30 and 200 mcg. Considerable variation of the muscular response occurs when the same dose is injected repeatedly at intervals of 30-60 sec.