Chloral hydrate and ethanol, but not urethane, alter the clearance of exogenous dopamine recorded by chronoamperometry in striatum of unrestrained rats

Several general anesthetics reduce dopamine (DA) neuronal activity and release. However, anesthetic-induced alterations in DA transporter (DAT) function are unclear. We used high-speed chronoamperometry to examine how urethane, chloral hydrate and ethanol affected clearance of locally-applied DA in the dorsal striatum of unrestrained rats. Maximal DA signal amplitudes (A_max) and signal decay rate constants (k) were monitored continuously from the awake to anesthetized state. Urethane did not significantly change A_max or k. Chloral hydrate and ethanol potentiated A_max by 32% and 37%, respectively, over baseline, indicative of DAT inhibition. These effects were not additive. Only ethanol increased k, an effect blocked by chloral hydrate. These results suggest differential effects of anesthetics on striatal DAT function, with chloral hydrate and ethanol significantly altering DAT activity but urethane producing only minimal effects.