The ethanol tissue sampling method for rCBF measurement was used to obtain information on the effects of cervical sympathetic stimulation in 8 cerebral structures in the non-anaesthetized rabbit. Sympathetic stimulation induced flow decreases of 12-29% according to structure, confirming the capability of this nerve to significantly reduce rCBF. Furthermore, a regional differentiation of cerebral structures into an 'anterior' group (mean decrease 22%) and a 'posterior' group (mean decrease 12%) with different reactivity to stimulation was established, thus confirming previous work in this laboratory with a local thermoclearance technique, and histochemical studies on sympathetic innervation to cerebral arteries and arterioles. These results provide strong evidence of the functional nature of the sympathetic nervous system in CBF regulation. The complementary nature of the ethanol technique (quantitative, multiregional measurement) and the local thermoclearance technique (continuous, semiquantitative measurements in 2-3 regions), and the absence of anaesthesia and significant trauma, means that combination of these two techniques offers considerable advantages in research on dynamic phenomena of the kind studied here.