title: Ghrelin signalling in guinea-pig femoral artery smooth muscle cells.
abstract: OBJECTIVE
  Our aim was to study the new signalling pathway of ghrelin in the guinea-pig femoral artery using the outward I(K) as a sensor.
  
  
  METHODS
  Whole-cell patch-clamp experiments were performed on single smooth muscle cells, freshly isolated from the guinea-pig femoral artery. The contractile force of isometric preparations of the same artery was measured using a wire-myograph.
  
  
  RESULTS
  In a Ca2+- and nicardipine-containing external solution, 1 mmol L(-1) tetraethylammonium reduced the net I(K) by 49 +/- 7%. This effect was similar and not additive to the effect of the specific BK(Ca) channel inhibitor iberiotoxin. Ghrelin (10(-7) mol L(-1)) quickly and significantly reduced the amplitudes of tetraethylammonium- and iberiotoxin-sensitive currents through BK(Ca) channels. The application of 5 x 10(-6) mol L(-1) desacyl ghrelin did not affect the amplitude of the control I(K) but it successfully prevented the ghrelin-induced I(K) decrease. The effect of ghrelin on I(K) was insensitive to selective inhibitors of cAMP-dependent protein kinase, soluble guanylyl cyclase, cGMP-dependent protein kinase or a calmodulin antagonist, but was effectively antagonized by blockers of BK(Ca) channels, phosphatidylinositol-phospholipase C, phosphatidylcholine-phospholipase C, protein kinase C, SERCA, IP(3)-induced Ca2+ release and by pertussis toxin. The ghrelin-induced increase in the force of contractions was blocked when iberiotoxin (10(-7) mol L(-1)) was present in the bath solution.
  
  
  CONCLUSIONS
  Ghrelin reduces I(K(Ca)) in femoral artery myocytes by a mechanism that requires activation of Galpha(i/o)-proteins, phosphatidylinositol phospholipase C, phosphatidylcholine phospholipase C, protein kinase C and IP(3)-induced Ca2+ release.
authors.affiliation: Department of Ion Channels, Institute of Biophysics, Bulgarian Academy of Sciences, Sofia, Bulgaria.
authors.forename: M I
authors.initials: MI
authors.lastname: Mladenov
authors.forename: K L
authors.initials: KL
authors.lastname: Hristov
authors.forename: D Z
authors.initials: DZ
authors.lastname: Dimitrova
authors.forename: D Z
authors.initials: DZ
authors.lastname: Dimitriova
authors.forename: R
authors.initials: R
authors.lastname: Schubert
authors.forename: L T
authors.initials: LT
authors.lastname: Lubomirov
authors.forename: I K
authors.initials: IK
authors.lastname: Gjorgoski
authors.forename: D B
authors.initials: DB
authors.lastname: Duridanova
authors.forename: H S
authors.initials: HS
authors.lastname: Gagov
mesh_terms: D000818:Animals; D004305:Dose-Response Relationship, Drug; D019332:Endothelin-1 / Q000494:pharmacology; D005263:Femoral Artery / Q000187:drug effects / Q000378:metabolism / Q000502:physiology; D054439:Ghrelin / Q000494:pharmacology*; D006168:Guinea Pigs; D051660:Intermediate-Conductance Calcium-Activated Potassium Channels / Q000187:drug effects / Q000378:metabolism; D008297:Male; D009131:Muscle, Smooth, Vascular / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism / Q000502:physiology; D032389:Myocytes, Smooth Muscle / Q000187:drug effects* / Q000378:metabolism / Q000502:physiology; D018408:Patch-Clamp Techniques; D010455:Peptides / Q000494:pharmacology; D054801:Phosphoinositide Phospholipase C / Q000502:physiology; D011493:Protein Kinase C / Q000502:physiology; D015398:Signal Transduction / Q000187:drug effects / Q000502:physiology; D010738:Type C Phospholipases / Q000502:physiology; D014661:Vasoconstriction / Q000187:drug effects / Q000502:physiology
chemical_list: D019332:Endothelin-1; D054439:Ghrelin; D051660:Intermediate-Conductance Calcium-Activated Potassium Channels; D010455:Peptides; C064719:iberiotoxin; D011493:Protein Kinase C; D010738:Type C Phospholipases; D054801:Phosphoinositide Phospholipase C; C105598:phosphatidylcholine-specific phospholipase C