Concentration-response of chloroethylclonidine-induced contraction in aorta from Wistar, WKY and SHR rats. Aortic rings were incubated with (±)-propranolol and rauwolscine (100 nM, each) prior to and during chloroethylclonidine (1–100 μM) exposure. Data shows the percentage of maximal noradrenaline effect (1.74±0.04, 1.01±0.04, 0.96±0.03 and g for Wistar, WKY and SHR, respectively), and represent the means±s.e.mean of 4–6 different animals. +P<0.05 vs WKY; *P<0.05 vs Wistar.