scholarly journals Inward current activated by carbachol in rat intestinal smooth muscle cells.

1993 ◽  
Vol 470 (1) ◽  
pp. 395-409 ◽  
Author(s):  
S Ito ◽  
T Ohta ◽  
Y Nakazato
Keyword(s):  
Smooth Muscle ◽  
Smooth Muscle Cells ◽  
Muscle Cells ◽  
Intestinal Smooth Muscle ◽  
Inward Current

Ca2+ currents in human colonic smooth muscle cells

1995 ◽  
Vol 269 (3) ◽  
pp. G378-G385 ◽  
Author(s):  
Z. Xiong ◽  
N. Sperelakis ◽  
A. Noffsinger ◽  
C. Fenoglio-Preiser
Keyword(s):  
Smooth Muscle ◽  
Smooth Muscle Cells ◽  
Cell Voltage ◽  
Muscle Cells ◽  
Human Colon ◽  
Physiological Salt Solution ◽  
Channel Blockers ◽  
Threshold Potential ◽  
Tissue Samples ◽  
Inward Current

Voltage-gated Ca2+ currents were investigated in single smooth muscle cells freshly isolated from the circular layer of the human colon (ascending and descending portions) using the whole cell voltage-clamp technique. Tissue samples were obtained at the time of therapeutic surgery. In physiological salt solution (containing 2 mM Ca2+), an inward current was observed when the cell membrane was depolarized in the presence of tetrodotoxin. This current disappeared when Ca2+ was removed from the bath solution and was inhibited when Ca2+ channel blockers were applied, indicating that the inward current was a Ca2+ current (ICa). Changing the holding potential (HP) from -100 mV to more positive potentials (e.g., -60 and -40 mV) markedly decreased the amplitude of ICa. The voltage dependence of steady-state activation and inactivation was represented by Boltzmann distributions; there was a substantial amount of overlap (window current) between -60 and -10 mV. A fast-inactivating ICa component followed by a slow-inactivating ICa component was observed in some cells from both ascending and descending colons. The fast ICa component was observed only when cells were held at -80 or -100 mV, and had a more negative threshold potential (-70 to -60 mV). This component was sensitive to low concentrations of Ni2+ (30 microM) but was resistant to nifedipine (10-20 microM). In contrast, the slow (sustained) ICa component was observed at all HPs (-40 to -100 mV) and had a more positive threshold potential (about -40 mV). This component was insensitive to low concentration of Ni2+ but was sensitive to nifedipine and BAY K 8644.(ABSTRACT TRUNCATED AT 250 WORDS)

IGFBP-3 activates TGF-β receptors and directly inhibits growth in human intestinal smooth muscle cells

2004 ◽  
Vol 287 (4) ◽  
pp. G795-G802 ◽  
Author(s):  
John F. Kuemmerle ◽  
Karnam S. Murthy ◽  
Jennifer G. Bowers
Keyword(s):  
Smooth Muscle ◽  
Smooth Muscle Cells ◽  
Nuclear Translocation ◽  
Thymidine Incorporation ◽  
Muscle Cells ◽  
Serine Phosphorylation ◽  
Intestinal Smooth Muscle ◽  
Igf I ◽  
Tgf Β1 ◽  
Igfbp 3

We have shown that human intestinal smooth muscle cells produce IGF-I and IGF binding protein-3 (IGFBP-3). Endogenous IGF-I acts in autocrine fashion to stimulate growth of these cells. IGFBP-3 inhibits the binding of IGF-I to its receptor and thereby inhibits IGF-I-stimulated growth. In several carcinoma cell lines and some normal cells, IGFBP-3 regulates growth independently of IGF-I. Two mechanisms for this effect have been identified: IGFBP-3 can directly activate transforming growth factor-β (TGF-β) receptors or it can undergo direct nuclear translocation. The aim of the present study was to determine whether IGFBP-3 acts independently of IGF-I and to characterize the mechanisms mediating this effect in human intestinal smooth muscle cells. The direct effects of IGFBP-3 were determined in the presence of an IGF-I receptor antagonist to eliminate its IGF-I-dependent effects. Affinity labeling of TGF-β receptors (TGF-βRI, TGF-βRII, and TGF-βRV) with 125I-labeled TGF-β1 showed that IGFBP-3 displaced binding to TGF-βRII and TGF-βRV in a concentration-dependent fashion. IGFBP-3 stimulated TGF-βRII-dependent serine phosphorylation (activation) of both TGF-βRI and of its primary substrate, Smad2(Ser465/467). IGFBP-3 also caused IGF-I-independent inhibition of basal [3H]thymidine incorporation. The effects of IGFBP-3 on Smad2 phosphorylation and on smooth muscle cell proliferation were independent of TGF-β1 and were abolished by transfection of Smad2 siRNA. Immunoneutralization of IGFBP-3 increased basal [3H]thymidine incorporation, implying that endogenous IGFBP-3 inhibits proliferation. We conclude that endogenous IGFBP-3 directly inhibits proliferation of human intestinal smooth muscle cells by activation of TGF-βRI and Smad2, an effect that is independent of its effect on IGF-I-stimulated growth.

Galanin contracts and relaxes guinea pig and canine intestinal smooth muscle cells through distinct receptors

1995 ◽  
Vol 108 (1) ◽  
pp. 3-11 ◽  
Author(s):  
Alain Botella ◽  
Michel Delvaux ◽  
Jean Fioramonti ◽  
Jacques Frexinos ◽  
Lionel Bueno
Keyword(s):  
Smooth Muscle ◽  
Guinea Pig ◽  
Smooth Muscle Cells ◽  
Muscle Cells ◽  
Intestinal Smooth Muscle

IGF-I increases IGFBP-5 and collagen α1(I) mRNAs by the MAPK pathway in rat intestinal smooth muscle cells

2004 ◽  
Vol 286 (5) ◽  
pp. G777-G783 ◽  
Author(s):  
Xiping Xin ◽  
Yong Tai Hou ◽  
Lina Li ◽  
Phyllissa Schmiedlin-Ren ◽  
Gregory M. Christman ◽  
...  
Keyword(s):  
Gene Regulation ◽  
Smooth Muscle ◽  
Crohn’S Disease ◽  
Smooth Muscle Cells ◽  
Mapk Pathway ◽  
Muscle Cells ◽  
Intestinal Smooth Muscle ◽  
Concurrent Treatment ◽  
Igf I ◽  
Docking Proteins

IGF-I is a potent fibrogenic growth factor that stimulates proliferation of intestinal smooth muscle cells and increases synthesis of collagen and IGF-I-binding proteins by the cells. These processes contribute to intestinal fibrosis that develops in patients with Crohn's disease and in Lewis-strain rats with experimental Crohn's disease. The aim of this study was to determine which early docking proteins are associated with IGF-I receptor signal transduction and which transduction pathway is involved in IGF-I-mediated gene regulation in intestinal smooth muscle cells. Primary cultures of smooth muscle cells isolated from the muscularis externa of the distal colon of Lewis rats were treated with IGF-I (100 ng/ml). Immunoprecipitation studies demonstrated that IGF-I stimulation resulted in tyrosine phosphorylation of IRS-1, IRS-2, and Shc. Coimmunoprecipitation demonstrated a close association between the IGF-I receptor and these three early docking proteins. Concurrent treatment with the MAPK inhibitor PD98059 (10 μM) resulted in an inhibition of the IGF-I-mediated increase in IGFBP-5 and collagen α1(I) mRNAs, while concurrent treatment with the phosphatidylinositol 3-kinase (PI3-K) inhibitor wortmannin (100 nM) had no effect. In additional experiments, cells were transiently transfected with adenoviral vectors dominantly expressing inactive mutant Akt or constitutively expressing wild-type Akt. In both cases, the IGF-I-mediated increase in collagen I protein did not differ from that observed in control cultures that had been transfected with an adenoviral vector carrying the LacZ reporter gene. These results suggest that the MAPK pathway is key to IGF-I-mediated gene regulation in intestinal smooth muscle cells, whereas data do not suggest a role for the Akt-dependent pathway in our system.

Multiple types of voltage-dependent Ca channels in mammalian intestinal smooth muscle cells

1989 ◽  
Vol 414 (4) ◽  
pp. 401-409 ◽  
Author(s):  
M. Yoshino ◽  
T. Someya ◽  
A. Nishio ◽  
K. Yazawa ◽  
T. Usuki ◽  
...  
Keyword(s):  
Smooth Muscle ◽  
Smooth Muscle Cells ◽  
Muscle Cells ◽  
Intestinal Smooth Muscle ◽  
Ca Channels ◽  
Voltage Dependent
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