Characterization of contractile function and expression of muscarinic receptors,G proteins and adenylate cyclase in cultured tracheal smooth muscle of Swine

Smooth muscle cells lose their contractile function and phenotype very rapidly when placed in culture. During organ culture of smooth muscle strips, phenotype is lost more slowly. In the present studies, we established an organ culture model to study contractile function and expression of muscarinic receptors, G proteins and adenylyl cyclase in different serum concentrations in tracheal smooth muscle from swine. The results show that contractile function and the amounts of M(3) receptors, G proteins and adenylyl cyclase were maintained for up to 5 days in culture. The expression of M(2) receptors was significantly decreased in culture when compared to freshly isolated muscles. Maximal isometric tension was significantly increased in cultured muscles compared with freshly isolated muscles. Different serum concentrations did not significantly affect contractile function and expression of muscarinic receptors, G proteins and adenylyl cyclase. In conclusion, our studies suggest that cultured smooth muscle might be used as a model to study the regulation of contractile function of smooth muscle by various signal transduction pathways.