VENTILATORY RESPONSE TO MUSCLE SPINDLE STIMULATION BY SUCCINYLCHOLINE IN CATS

In anesthetized cats, hind limb muscle spindle receptors were stimulated by injection into the abdominal aorta of succinylcholine at a dosage which did not induce muscular contraction. After a few seconds delay, ventilatory activity and cardiac frequency increased. Lumbar cordotomy abolished the ventilatory and cardiac responses to the injection of succinylcholine. Furthermore NaCN injections into the abdominal aorta were followed by respiratory responses delayed with respect to those observed after succinylcholine injection. The stimulation of the muscle spindle receptors by succinylcholine causes a reflex hyperventilation. This observation emphasizes the role of these receptors in the regulation of ventilation when they are naturally stimulated by mechanical factors during natural muscular exercise. © 1969.