Abstract
Barbiturates are generally thought to act chiefly on the brain, 1 strychnine to exert its convulsant effects by an action on the cord. 2 If this were an absolute difference between the two, it would be difficult to see how the barbiturates could act as effective antagonists to strychnine, as numerous observers 3 have shown.
To test whether this antagonism does exist in the cord, the writers have made use of 9 spinal (decapitate) cats, prepared by the Sherrington method. 4 Strychnine sulphate was administered subcutaneously in doses of 0.75 or 1 mg. per kg. Violent convulsions followed in all cases, marked by typical repeated rigid extensor tetanus. When this stage was reached, a barbiturate solution was injected intravenously. This injection was followed in each case instantly by muscular relaxation. Threatened or actual recurrence of tetanus was met by further doses of barbiturate. The animals survived for varying lengths of time from 24 minutes up to several hours after tetanus appeared. Three control animals receiving strychnine alone showed recurrent tetanus for 20 to 80 minutes after its onset. All doses were based on weight of intact cat.
The results are summarized in Tables I and II.
Comment on Tables. “Survival”—disappearance of reflexes and of heart beat were usually nearly simultaneous, the survival period being between limits given. Notes on individual experiments. Na pentobarbital—recurrence of tetanus after 26 minutes shows that the strychnine dosage used is capable of causing a prolonged tetanic stage; observation was interrupted 70 minutes after the second tetanus, the preparation was left on artificial respiration and was in good condition 4 1/2 hours later. Na amytal—it will be noted that the abolition of tetani may result from even very moderate dosage with barbiturate, but that this does not necessarily restore to the spinal cat preparation its normal viability of many hours.
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