Abstract
Sabbatini observed that the direct application of isotonic solutions of oxalate or of citrate to the exposed brain of dogs increased their excitability and at times resulted in a generalized convulsion. 1 This effect was antagonized by calcium. We have repeated and extended these experiments. Small amounts (0.1-0.3 cc.) of isotonic solutions of either sodium citrate (0.077 M), calcium chloride (0.107 M), calcium citrate (0.06 M), or magnesium chloride (0.107 M) were injected into the cisterna magna of dogs, using a fine needle (26 gauge).
A typical syndrome occurred following injections of sodium citrate, consisting of immediate contraction of the voluntary muscles of the neck, trunk, extremities and tail. The motor phenomena included an extensor rigidity of the legs, slightly greater in the fore legs than in the hind, and a marked opisthotonos, pleurothotonos, and dorsal curvature of the tail. The heart rate slowed during this phase of the effect and was accelerated during the recovery period. Profuse salivation occurred. The intense motor excitation lasted usually from 5 to 15 minutes, but the animals were ataxic and had an unsteady wide-based gait for a somewhat longer period. In a minority of cases a generalized tonic and clonic convulsion followed the original motor spasm. The animals were usually normal 30 minutes after the injection.
In some of the experiments, the needle was left in the cisterna following citrate injection and, as soon as the motor reaction was obtained, calcium chloride or magnesium chloride was injected in amounts equivalent to the sodium citrate. The hypertonic muscles relaxed in a few seconds and within a few minutes the animal appeared to be normal.
Injections of Ringer's solution and sodium chloride in these small doses were without apparent effect.
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