The Local Anticonvulsive Action of Calcium Salts. ∗

Abstract

Using Beutner and Miley's method, 1 it was found that 200 mg per kg of procaine HC1 injected intramuscularly into 56 guinea pigs caused clonic and tonic convulsions in all of the animals. The convulsions lasted 51 minutes on the average, and were preceded by hind leg stiffness. One hundred mg per kg of procaine HC1 produced convulsions in 84% of 204 observations, with an averge duration of 12 minutes, while 50 mg per kg acted in only 8% of the animals with an average duration of 8 minutes.

If CaCl₂ was added to the procaine HC1 solution and injected simultaneously, a marked decrease in the incidence of these convulsions was invariably observed. Thus, 200 mg per kg of CaCl₂ with 200 mg per kg of procaine HC1 reduced the incidence of convulsions to 43% in 30 trials. Similarly, 100 mg per kg of CaCl₂ added to 100 mg per kg of the procaine solution reduced the incidence to 14% in 122 cases. This inhibiting effect of CaCl₂ on procaine convulsions is much less if CaCl₂ is injected separately from procaine.

The nature of the local action of CaCl₂ in reducing procaine convulsions may be clarified if one notes the effect of MgCl₂ added to the procaine-CaCl₂ mixture. Two hundred mg per kg of MgCl₂ was added to and injected intramuscularly in guinea pigs with 100 mg per kg of both procaine HC1 and CaCl₂. In 137 experiments, the incidence of convulsions was 33%, or more than twice what we found it to be without MgCl₂. This indicates that MgCl₂ counteracts CaCl₂ locally, probably by altering membrane permeability as in the case of calcium-magnesium antagonism in the Meltzer-Auer phenomenon.