Effect of chronic cocaine exposure on the hemodynamic response to vasopressors in sheep.

BACKGROUND

The purpose of this study was to determine how chronic cocaine exposure affects the hemodynamic response to epinephrine, dopamine, phenylephrine, and ephedrine in awake sheep.

METHODS

The hemodynamic response to dopamine (10 microg/kg), phenylephrine (1.5 microg/kg), and ephedrine (0.15 mg/kg) boluses was determined at baseline before low-dosage cocaine exposure and again after 15 and 18 days of cocaine exposure. The hemodynamic response to epinephrine (0.15 microg/kg), phenylephrine (1.5 microg/kg), and ephedrine (0.15 mg/kg) was determined at baseline before high-dosage cocaine exposure and again after 15 and 18 days of cocaine exposure.

RESULTS

Chronic cocaine exposure abolished the mean arterial pressure and heart rate responses to dopamine but did not alter the responses to epinephrine, phenylephrine, or ephedrine.

CONCLUSION

In awake sheep, chronic cocaine exposure markedly impairs the hemodynamic response to dopamine but not to epinephrine, phenylephrine, or ephedrine.