The functional effects of sigma and PCP receptor ligands were examined in the perfused rat tail artery. The following ligands were studied: haloperidol; (+)-3-PPP [(+)-3-(3-hydroxyphenyl)-N-(1-propyl)piperidine]; (+-)-BMY 14802 [(+-)-alpha-(4-fluorophenyl)-4-(5-fluoro-2-pyrimidinyl)-1-piperazine butanol]; DTG [1,3-di-orthotolyl-guanidine]; rimcazole (BW 234U) [cis-9-[3-(3,5-dimethyl-1-piperazinyl)propyl]carbazole dihydrochloride]; (+)-SKF 10047 [(+)-N-allyl-N-normetazocine]; TCP, [1-[1-(2-thienyl)cyclohexyl] piperidine]; and MK 801 [(+)-5-methyl-10,11-dihydro-5H-dibenzo[a,d]cyclohepten-5,10-imine maleate]. (+)-3-PPP, (+)-SKF 10047, MK 801 and TCP potentiated contractile responses to norepinephrine, an effect which was blocked by cocaine implying an action of these agents on monoamine uptake. In the presence of cocaine an additional postjunctional inhibitory action of (+)-3-PPP and (+)SKF 10047 on norepinephrine-induced contractile responses was unveiled. In contrast, haloperidol, (+/-)-BMY 14802, rimcazole and DTG inhibited contractile responses to norepinephrine. Haloperidol, (+/-)-BMY 14802 and (+)-SKF 10047 (+ uptake blockade) also inhibited contractile responses to serotonin. The order of potency for inhibition of norepinephrine-induced contractions was haloperidol greater than (+/-)-BMY 14802 greater than (+)-3-PPP greater than rimcazole greater than (+)-SKF 10047 (+ uptake blockade) greater than DTG. These studies demonstrate the lack of selectivity of many sigma and PCP ligands, significant effects on norepinephrine uptake, as well as the potential utility of the rat tail artery to explore the functional properties of these ligands.