The effects of 7,8-(methylenedioxi)-14-α-hydroxyalloberbane HCl (CH-38083), a structurally new, selective and potent alpha2-adrenoceptor antagonist, and of idazoxan, were studied on both the spontaneous activity of the postganglionic sympathetic renal nerve and on the clonidine- or xylazineinduced inhibitory action in anaesthetized cats. The drug CH-38083 (30-200 μg/kg, i.v.) caused a sustained increase of the sympathetic activity and blood pressure. Larger doses of idazoxan (200-500 μg/kg, i.v.) were needed to induce similar effects. Both antagonists were effective in antagonizing the sympathoinhibitory effect of clonidine or xylazine. The excitatory response to selective alpha2-adrenoceptor antagonists suggests that the sympathetic output undergoes tonic inhibition due to a permanent alpha2-adrenoceptor stimulation.
- renal sympathetic nerve activity
ASJC Scopus subject areas
- Cellular and Molecular Neuroscience