[3H] cloni-[3H] rauwol-[3H] prazocompd dine (ap) scine (az) sin (a1) selectivity* 6a 1.36 f 0.16 1.6 f 0.5 210 f 30 130 6b 0.77 f 0.19 1.1 f 0.3 110 f 30 100 6c 100 f 10 190 f 7.7 8000 f 700 42 yohimbine 49 f 1 10.0 f 2.1 220 f 10 22 OValues are means f SD for at least three separate determinations.* Ki [3H] prazosin/Ki [3H] rauwolscine.