Effects of HA-1077 and Y-27632, two rho-kinase inhibitors, in the human umbilical artery.
A role for the small G protein rho and rho-kinase has been shown in smooth muscle contraction regarding Ca++ sensitivity. However, there are no data in the literature assessing how this system operates in human umbilical arteries (HUA). Therefore, we evaluated the effects of HA-1077 and Y-27632, two rho-kinase inhibitors, on agonist-(5-hydroxytryptamine [5-HT]) and depolarization-induced (KCl) contractions of HUA. HA-1077 and Y-27632 inhibited 5-HT-induced contractile responses at 10-4M concentration but not at 10(-5) M. HA-1077 at 10(-4) M also significantly attenuated contractions induced by 20 mM KCl. In addition, HUA precontracted with 5-HT relaxed concentration dependently in response to HA-1077 and Y-27632. When precontracted with KCl, HUA also relaxed dose-dependently in response to HA-1077, but the maximal relaxation was significantly smaller than the response obtained when precontracted with 5-HT. To determine possible involvement of rho-kinase on agonist-induced intracellular calcium-mediated contractions, tissues were precontracted with 5-HT in Ca++-free Krebs solution before cumulative addition of HA-1077 or Y-27632 (10(-7) to 10(-4) M). Both rho-kinase inhibitors relaxed HUA completely. Maximum relaxations of HUA to HA-1077 and Y-27632 were significantly larger than the responses seen in normal Krebs solution and were obtained with lower concentrations of the drugs considered to be more specific for rho-kinase inhibition. However, preincubation of HUA with HA-1077 or Y-27632 (10(-5) M for both) did not affect the 5-HT-induced contractions in this medium. Finally, immunoblot experiments revealed the expression of rho-kinase isoform rockII protein in HUA. These results indicate that rhoA/rho-kinase pathway can contribute to agonist-induced contractions of HUA. However, this effect appears to be limited to intracellular calcium-induced contractions and may be more important in sustaining contractions rather than the initial phase of force development.
Ark
Mustafa
M
Department of Pharmacology, Mersin University, Faculty of Medicine, Mersin, Turkey. mark@mersin.edu.tr
Ozveren
Elif
E
Yazici
Gürkan
G
Korkmaz
Belma
B
Büyükafsar
Kansu
K
Arikan
Onur
O
Kubat
Havva
H
Songu-Mize
Emel
E
D019307:1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine / Q000031:analogs & derivatives* / Q000494:pharmacology; D000577:Amides / Q000494:pharmacology*; D001703:Biophysics / Q000379:methods; D002118:Calcium / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D006801:Humans; D008954:Models, Biological; D009543:Nifedipine / Q000494:pharmacology; D011189:Potassium Chloride / Q000494:pharmacology; D020033:Protein Isoforms; D047428:Protein Kinase Inhibitors / Q000494:pharmacology*; D011725:Pyridines / Q000494:pharmacology*; D012701:Serotonin / Q000378:metabolism; D014469:Umbilical Arteries / Q000187:drug effects / Q000201:enzymology*; D054460:rho-Associated Kinases / Q000037:antagonists & inhibitors* / Q000378:metabolism
D000577:Amides; D020033:Protein Isoforms; D047428:Protein Kinase Inhibitors; D011725:Pyridines; C108830:Y 27632; D012701:Serotonin; D011189:Potassium Chloride; D019307:1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine; D054460:rho-Associated Kinases; D009543:Nifedipine; C049347:fasudil; D002118:Calcium