Abstract
The influence of various α‐adrenoceptor antagonists (phentolamine, yohimbine, R 28935, prazosine, terazosine) on clonidine's blood pressure effects at different steady state plasma concentrations was investigated in awake spontaneous hypertensive rats. Clonidine's threshold (>10 mmHg,1‐and α2‐antagonists. The effect of clonidine on blood pressure thus seems a consequence of both the tissue distribution and the α‐adrenoceptor affinity. At low steady state plasma concentrations of clonidine a peripheral action could be a part of the antihypertensive mechanism.