CARDIOVASCULAR EFFECTS OF COCAINE DURING OPERANT COCAINE SELF-ADMINISTRATION

The aim of this study was to investigate the acute and chronic effects of cocaine self-administration behavior on cardiovascular function. M ean blood pressure and heart rate were measured by radio-telemetry dur ing several experimental conditions. Initial control studies eliminate d possible confounds related to the effects of saline injections and o perant responding on heart rate and blood pressure. When rats were fir st allowed to self-administer 0.5-mg/kg injections of cocaine (FR(fixe d ratio)10:TO 30 s), there was a significant increase in blood pressur e. Tolerance developed to this effect within 3 daily sessions. A signi ficant decrease in blood pressure and heart rate was observed during s aline-substitution sessions. Increasing the injection dose of cocaine (1.0, 2.0 and 4.0 mg/kg per injection) did not produce a dramatic incr ease in blood pressure or heart rate despite significant cumulative co caine intake (20-27 mg/kg). The cardiovascular effects of cocaine admi nistration did not approach magnitudes previously reported. The result s of the current study suggest that operant-conditioned behavior and/o r the direct reinforcing effects of cocaine modulates the cardiovascul ar effects of cocaine.