Fig. 9.

Substitution for the discriminative stimulus effects of carisoprodol. Top, percentage of total responses made on the carisoprodol-appropriate lever. Bottom, rate of responding in responses per second (r/s). Carisoprodol, pentobarbital, meprobamate, and chlordiazepoxide fully substituted for the discriminative stimulus effects of 100 mg/kg carisoprodol. Carisoprodol produced a modest increase in response rate, whereas chlordiazepoxide produced no effect, and pentobarbital markedly reduced rates at the highest doses tested (n = 10 rats).