Contribution of Rho-kinase in human gallbladder contractions.
Rho/Rho-kinase-mediated pathway has been involved in a variety of physiological processes, including Ca2+ sensitization, which enhances smooth muscle contraction. In this study, first of all we investigated the expression of Rho-kinase (ROCK-2) and then the role of this protein in the control of smooth muscle contraction in the isolated human gallbladder. For this purpose, we examined the effects of a selective Rho-kinase inhibitor, (+)- (R)-trans-4-(1-aminoethyl)-N-(4-pyridyl) cyclohexanecarboxamide dihydrochloride monohydrate (Y-27632, 10(-8)-3x10(-5) M) on carbachol (10(-8)-10(-4) M), cholecystokinin-8 (10(-8) M), endothelin-1 (10(-8) M), histamine (10(-5) M), neurokinin A (10(-7)-10(-6) M), 5-hydroxytryptamine (10(-6)-10(-5) M) and potassium chloride (KCl, 25-50 mM)-induced contractions as well as spontaneous contractile activity. Y-27632 (10(-5) M) significantly reduced 5-hydroxytryptamine, neurokinin A and KCl-induced contractions. Moreover, this Rho-kinase inhibitor (10(-8)-3x10(-5) M, cumulatively) relaxed the contractions produced by cholecystokinin-8, endothelin-1 and histamine in a concentration-dependent manner, being the pEC50 values for Y-27632 5.74+/-0.12, 5.33+/-0.09 and 5.95+/-0.18, respectively. Carbachol (10(-8)-10(-4) M) produced concentration-dependent contractions, which were also inhibited significantly by Y-27632. In addition, the spontaneous contractile activity was suppressed in the presence of Y-27632 (10(-6)-10(-5) M). Moreover, Western blot analysis has revealed that Rho-kinase is expressed in homogenates of the human gallbladder. Taken together, these results show that Rho-kinase is expressed in the human gallbladder, and it has an essential role in agonists and depolarization-induced contractions as well as spontaneous contractile activity.
Büyükafşar
Kansu
K
Department of Pharmacology, Medical Faculty, Mersin University, Campus Yenişehir 33169 Mersin, Turkey. kbuyukafsar@mersin.edu.tr
Akça
Tamer
T
Nalan Tiftik
Rukiye
R
Sahan-Firat
Seyhan
S
Aydin
Süha
S
D000368:Aged; D000577:Amides / Q000494:pharmacology; D015153:Blotting, Western; D002217:Carbachol / Q000494:pharmacology; D002766:Cholecystokinin / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D019332:Endothelin-1 / Q000494:pharmacology; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005260:Female; D005704:Gallbladder / Q000187:drug effects / Q000502:physiology*; D006632:Histamine / Q000494:pharmacology; D006801:Humans; D066298:In Vitro Techniques; D047908:Intracellular Signaling Peptides and Proteins / Q000037:antagonists & inhibitors / Q000378:metabolism*; D008297:Male; D008875:Middle Aged; D009119:Muscle Contraction / Q000187:drug effects / Q000502:physiology*; D015288:Neurokinin A / Q000494:pharmacology; D010446:Peptide Fragments / Q000494:pharmacology; D011189:Potassium Chloride / Q000494:pharmacology; D017346:Protein Serine-Threonine Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism*; D011725:Pyridines / Q000494:pharmacology; D012701:Serotonin / Q000494:pharmacology; D054460:rho-Associated Kinases
D000577:Amides; D019332:Endothelin-1; D004791:Enzyme Inhibitors; D047908:Intracellular Signaling Peptides and Proteins; D010446:Peptide Fragments; D011725:Pyridines; C410885:cholecystokinin 8; C108830:Y 27632; D012701:Serotonin; D011189:Potassium Chloride; D006632:Histamine; D015288:Neurokinin A; D002217:Carbachol; D002766:Cholecystokinin; D017346:Protein Serine-Threonine Kinases; D054460:rho-Associated Kinases