Smooth Muscle Contraction

Edited: Gillespie, ME, 2009-11-18 Reviewed: Rush, MG, 2008-01-11 00:00:00 Layers of smooth muscle cells can be found in the walls of numerous organs and tissues within the body. Smooth muscle tissue lacks the striated banding pattern characteristic of skeletal and cardiac muscle. Smooth muscle is triggered to contract by the autonomic nervous system, hormones, autocrine/paracrine agents, local chemical signals, and changes in load or length.<br> Actin:myosin cross bridging is used to develop force with the influx of calcium ions (Ca2+) initiating contraction. Two separate protein pathways, both triggered by calcium influx contribute to contraction, a calmodulin driven kinase pathway, and a caldesmon driven pathway.<br> Recent evidence suggests that actin, myosin, and intermediate filaments may be far more volatile then previously suspected, and that changes in these cytoskeletal elements along with alterations of the focal adhesions that anchor these proteins may contribute to the contractile cycle.<br> Contraction in smooth muscle generally uses a variant of the same sliding filament model found in striated muscle, except in smooth muscle the actin and myosin filaments are anchored to focal adhesions, and dense bodies, spread over the surface of the smooth muscle cell. When actin and myosin move across one another focal adhesions are drawn towards dense bodies, effectively squeezing the cell into a smaller conformation. The sliding is triggered by calcium:caldesmon binding, caldesmon acting in an analogous fashion to troponin in striated muscle. Phosphorylation of myosin light chains also is involved in the initiation of an effective contraction.<br> Authored: Gillespie, ME, 2009-03-09 02:39:27

http://purl.obolibrary.org/obo/HINO_0016385

Edited: Gillespie, ME, 2009-11-18

Reviewed: Rush, MG, 2008-01-11 00:00:00

Layers of smooth muscle cells can be found in the walls of numerous organs and tissues within the body. Smooth muscle tissue lacks the striated banding pattern characteristic of skeletal and cardiac muscle. Smooth muscle is triggered to contract by the autonomic nervous system, hormones, autocrine/paracrine agents, local chemical signals, and changes in load or length.
Actin:myosin cross bridging is used to develop force with the influx of calcium ions (Ca2+) initiating contraction. Two separate protein pathways, both triggered by calcium influx contribute to contraction, a calmodulin driven kinase pathway, and a caldesmon driven pathway.
Recent evidence suggests that actin, myosin, and intermediate filaments may be far more volatile then previously suspected, and that changes in these cytoskeletal elements along with alterations of the focal adhesions that anchor these proteins may contribute to the contractile cycle.
Contraction in smooth muscle generally uses a variant of the same sliding filament model found in striated muscle, except in smooth muscle the actin and myosin filaments are anchored to focal adhesions, and dense bodies, spread over the surface of the smooth muscle cell. When actin and myosin move across one another focal adhesions are drawn towards dense bodies, effectively squeezing the cell into a smaller conformation. The sliding is triggered by calcium:caldesmon binding, caldesmon acting in an analogous fashion to troponin in striated muscle. Phosphorylation of myosin light chains also is involved in the initiation of an effective contraction.

Authored: Gillespie, ME, 2009-03-09 02:39:27

Reactome, http://www.reactome.org

Pubmed18596210

Pubmed14627618

Pubmed10679361

Smooth Muscle Contraction

http://purl.obolibrary.org/obo/NCBITaxon_9606

HINO:0016385

Smooth Muscle Contraction

GENE ONTOLOGYGO:0006936

ReactomeREACT_20558

Reactome Database ID Release 43445355

http://purl.obolibrary.org/obo/INO_0000021

http://purl.obolibrary.org/obo/HINO_0025333

http://purl.obolibrary.org/obo/HINO_0025336

http://purl.obolibrary.org/obo/HINO_0025335

http://purl.obolibrary.org/obo/HINO_0025334

http://purl.obolibrary.org/obo/HINO_0025330

http://purl.obolibrary.org/obo/HINO_0025329

http://purl.obolibrary.org/obo/HINO_0024853