Effects of kappa, sigma, and phencyclidine receptors agonists in rat tail arteries of spontaneously hypertensive rats

The effects of the kappa receptor agonist trans-4-dichloro-N-methyl-N-(2-(1-pyrrolidin)cyclohexyl)-benzen eacefamide methane sulfonate (U-50 488H), etorphine, the sigma (sigma) receptor agonists (+)-3-(3-hydroxychenyl)-N-(1-propyl) piperidine ((+)-3-PPP), 1, 3-di-o-tolyl-guanidine (DTG), and the phencyclidine (Phe) receptor agonists Phe, N-(1-(2-thienyl)cyclohexyl) piperidine (TCP), and dizocilipine maleate (MK-801) on electrically stimulated constriction (ESC) were investigated in the rat tail arteries (RTA) of spontaneously hypertensive rats (SHR) and normotensive Wistar-Kyoto (WKY) rats. Etorphine and U-50 488H inhibited the response to ESC in SHR more than that in WKY. The effects of U-50 488H were greater than those of etorphine. The IC50 and Kact of U-50 488H in SHR were 2.5 +/- 2.0 and 0.43 +/- 0.22 mumol.L-1, respectively, while the corresponding figures in WKY were 23 +/- 15 and 2.3 +/- 1.0 mumol.L-1, respectively (P < 0.05). The inhibitory effects of (+)-3-PPP on ESC in RTA of SHR were weaker than those in WKY. Its IC50 and Kact in SHR were 11.6 +/- 5.4 and 0.87 +/- 0.30 mumol.L-1, respectively, while the corresponding figures in WKY were 0.63 +/- 0.16 and 0.35 +/- 0.18 mumol.L-1, respectively (P < 0.05). But the inhibitory effect of DTG was very slight and the difference of Kact between WKY and SHR was not significant. The enhancing effects of Phe, TCP, and MK-801 in SHR were not at all different from those in WKY at each concentration tested.(ABSTRACT TRUNCATED AT 250 WORDS)