Abstract

The vasodilator and antiproliferative actions of 1,3-dihydro-3-p-chlorophenyl-7-hydroxy-6-methyl-furo-(3,4c) pyridine hydrochloride (cicletanine) were studied on mesenteric resistance arteries and cultured mesenteric artery myocytes of spontaneously hypertensive (SHR) and normotensive Wistar Kyoto (WKY) rats. Cicletanine (20-200 microM) induced relaxation of endothelium-intact mesenteric resistance arteries of SHR and WKY precontracted with norepinephrine. No difference in sensitivity was observed (SHR IC50 = 77 +/- 12 microM vs. 83.3 +/- 7.4 microM for WKY, N.S.). Endothelial denudation of WKY vessels significantly attenuated the relaxing action of cicletanine (IC50 + endo = 83 +/- 7.4 microM vs. IC50 - endo = 135 +/- 9.7 microM; P < .001) and had a similar, but nonsignificant effect on SHR (IC50 + endo = 77 +/- 12 microM vs. IC50 - endo = 117 +/- 14.5 microM; P = .065). Preincubation of endothelium-intact vessels with nitro-L-arginine methyl ester significantly attenuated cicletanine-induced relaxation in WKY, but not SHR vessels; 0.1 mM Ba++ had a similar effect. Preincubation with 3 microM indomethacin was without effect on relaxation of vessels of either strain. Cicletanine (100-1000 microM) inhibited proliferation of cultured superior mesenteric artery muscle cells growing in the presence of either 10% (SHR IC50 = 440 +/- 24 microM vs. 517 +/- 12 microM for WKY; P < .05) or 2% fetal bovine serum. This antiproliferative action was fully reversible, partially inhibited by indomethacin in SHR myocytes and was associated with a decrease in [3H]thymidine uptake in both strains.(ABSTRACT TRUNCATED AT 250 WORDS)