Cardiovascular effects in the rat of intrathecal injections of apomorphine at the thoracic spinal cord level.

Intrathecal (i.t.) administration of apomorphine at the upper thoracic level lowered blood pressure and heart rate in awake rats. This decrease was dose-dependent and competitively antagonized by haloperidol (i.v. and i.t.) or domperidone (i.t.) but not by domperidone (i.v.). Furthermore, these effects of apomorphine were not affected by alpha- and beta-blocking drugs (i.t.). The results suggest a spinal site, at least in part, for the cardiovascular effect of apomorphine.