Prisca Mbikou (Author), Aleš Fajmut (Author), Milan Brumen (Author), Etienne Roux (Author)

Abstract

We investigated theoretically and experimentally the ▫$Ca^{2+}$▫-contraction couplingin rat tracheal smooth muscle. ▫$[Ca^{2+}]_i$▫, isometric contraction and myosin light chain (MLC) phosphorylation were measured in response to 1 mM carbachol. Theoretical modeling consisted in coupling a model of ▫$Ca^{2+}-dependent$▫ MLC kinase (MLCK) activation with a four-state model of smooth muscle contractile apparatus. Stimulation resulted in a short-time contraction obtained within 1 min, followed by a long-time contraction up to the maximal force obtained in 30 min. ML-7 and Wortmannin (MLCK inhibitors) abolished the contraction. Chelerythrine (PKC inhibitor) did not change the short-time, but reduced the long-time contraction. ▫$[Ca^{2+}]_i$▫ responses of isolated myocytes recorded during the first 90 s consisted in a fast peak, followed by a plateau phase and, in 28 % of the cells, superimposed ▫$Ca^{2+}$▫ oscillations. MLC phosphorylation was maximal at 5 s and then decreased, whereas isometric contraction followed a Hill-shaped curve. The model properlypredicts the time course of MLC phosphorylation and force of the short-time response. With oscillating ▫$Ca^{2+}$▫ signal, the predicted force does not oscillate. According to the model, the amplitude of the plateau and the frequency of oscillations encode for the amplitude of force, whereas the peak encodes for force velocity. The long-time phase of the contraction, associated with a second increase in MLC phosphorylation, may be explained, at least partially, by MLC phosphatase (MLCP) inhibition, possibly via PKC inhibition.

Keywords

biofizika;matematično modeliranje;modeliranje;kalcijeve oscilacije;gladke mišice;krčenje mišic;miozin kinaza;razvoj sile;matematični modeli;ne zaključna dela;biophysics;mathematical modelling;modelling;calcium oscillations;contractions;force development;muscle cells;smooth muscles;myosin kinase;

Data

Language: English
Year of publishing:
Typology: 1.01 - Original Scientific Article
Organization: UM PEF - Faculty of Education
UDC: 577.353
COBISS: 15168776 Link will open in a new window
ISSN: 1085-9195
Views: 1863
Downloads: 95
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Other data

Secondary language: Slovenian
Secondary keywords: Biofizika;
URN: URN:SI:UM:
Type (COBISS): Article
Pages: str. 233-251
Volume: ǂVol. ǂ46
Issue: ǂno. ǂ3
Chronology: 2006
ID: 8724209