Cultured gastrointestinal smooth muscle cells: cell response to contractile agonists depends on their phenotypic state.
In the digestive tract, the transit of ingested food induces a local contraction-relaxation reflex of which the smooth muscle cell (SMC) represents the functional unit. Although freshly isolated SMCs have been extensively used for in vitro studies, in specific cases cultured cells appear necessary. Because conventionally cultured SMCs lose their contractile properties, we have developed: (1) differentiated, contractile rabbit gastric SMCs (D-stim cells), cultured in a medium supplemented with insulin, and (2) proliferative, dedifferentiated rabbit gastric SMCs (P-stim cells), cultured in a medium supplemented with insulin, fetal serum, EGF and b-FGF. The proliferative index was 5 +/- 4% and 82 +/- 10%, respectively, for D-stim and P-stim cells. Expression of SM-myosin heavy chain was observed in 90% of D-stim cells, whereas it was progressively lost in P-stim cells. Carbachol (1-100 nM), glicentin (2 nM) and gastrin-17 (100 nM) induced contraction of D-stim cells cultured for 3 or 6 days, whereas they did not induce the contraction of P-stim cells; in contrast, gastrin-17 (10 nM) was able to stimulate DNA synthesis (1.86 +/- 0.09-fold increase) in P-stim cells. The coupling of muscarinic receptors to intracellular transduction pathways was evaluated in D-stim cells: at day 3, carbachol (100 nM) induced a twofold increase in the production of inositol tri-tetra-phosphates; in parallel, a phosphorylation of ERK MAP kinases occurred within 1 min of carbachol stimulation. In conclusion, cultured functional myocytes derived from mature tissue may be used for long-term studies concerning the events coupled either to proliferation or to motility regulation of differentiated SMCs due to the activation of G-protein-coupled receptors.
Jarrousse
Claire
C
Signalisation Cellulaire Normale et Tumorale, EA 2995, Faculté de Pharmacie, 15 Avenue Charles Flahault, 34093 Montpellier cedex 5, France.
Lods
Nadege
N
Michel
Francoise
F
Bali
Jean Pierre
JP
Magous
Richard
R
D000818:Animals; D002217:Carbachol / Q000494:pharmacology; D002454:Cell Differentiation / Q000187:drug effects*; D049109:Cell Proliferation / Q000187:drug effects; D002478:Cells, Cultured; D048049:Extracellular Signal-Regulated MAP Kinases / Q000187:drug effects / Q000378:metabolism; D005755:Gastrins / Q000494:pharmacology; D053771:Glicentin; D005934:Glucagon / Q000494:pharmacology; D004763:Glucagon-Like Peptides; D007295:Inositol Phosphates / Q000378:metabolism; D009119:Muscle Contraction; D009130:Muscle, Smooth / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D018995:Myosin Heavy Chains / Q000378:metabolism; D010446:Peptide Fragments / Q000494:pharmacology; D011498:Protein Precursors / Q000494:pharmacology; D011706:Pyloric Antrum / Q000166:cytology / Q000378:metabolism*; D011817:Rabbits; D011976:Receptors, Muscarinic / Q000378:metabolism; D015398:Signal Transduction / Q000187:drug effects*
D005755:Gastrins; D007295:Inositol Phosphates; D010446:Peptide Fragments; D011498:Protein Precursors; D011976:Receptors, Muscarinic; C013550:gastrin 17; D004763:Glucagon-Like Peptides; D053771:Glicentin; D002217:Carbachol; D005934:Glucagon; D048049:Extracellular Signal-Regulated MAP Kinases; D018995:Myosin Heavy Chains