Force-velocity relation and rate of ATP hydrolysis in osmotically compressed skinned smooth muscle of the guinea pig

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T1 - Force-velocity relation and rate of ATP hydrolysis in osmotically compressed skinned smooth muscle of the guinea pig

AU - Arheden, Håkan

AU - Arner, Anders

AU - Hellstrand, Per

PY - 1987

Y1 - 1987

N2 - Chemically skinned guinea pig taenia coli fibre bundles showed a concentration-dependent decrease in width when incubated in media containing Dextran T500 (0-0.2 g ml-1). The maximal reduction in width, observed at 0.2 g ml-1 dextran, was 32%. The effect was reversible upon removal of dextran. Isometric force was slightly increased (about 10%) at the lowest dextran concentration (0.025 g ml-1) but decreased at higher concentrations (40% decrease at 0.2 g/ml-1). The energetic tension cost (ATP turnover/force) was decreased by about 40% after dextran addition. Force development and relaxation were markedly slower in 0.1 g ml-1 and absent in 0.2 g ml-1 dextran. In isotonic quick-release experiments 0.025 g ml-1 dextran did not influence maximal shortening velocity (Vmax) and relative stiffness, whereas 0.1 g ml-1 markedly increased stiffness and decreased Vmax to about 27%. Vanadate induced relaxation in the activated muscle (pCa 4.5) both in the absence and presence (0.1 g ml-1) of dextran and increased the rate of relaxation (pCa 9) at 0.1 g ml-1 dextran. The isometric rate of crossbridge turnover, as reflected by the energetic tension cost and the rate of relaxation, was decreased at all degrees of osmotic compression. Crossbridge turnover rate during shortening (Vmax) was unaffected at an osmotic compression of 12% (width) but was decreased at higher compression (32%).

AB - Chemically skinned guinea pig taenia coli fibre bundles showed a concentration-dependent decrease in width when incubated in media containing Dextran T500 (0-0.2 g ml-1). The maximal reduction in width, observed at 0.2 g ml-1 dextran, was 32%. The effect was reversible upon removal of dextran. Isometric force was slightly increased (about 10%) at the lowest dextran concentration (0.025 g ml-1) but decreased at higher concentrations (40% decrease at 0.2 g/ml-1). The energetic tension cost (ATP turnover/force) was decreased by about 40% after dextran addition. Force development and relaxation were markedly slower in 0.1 g ml-1 and absent in 0.2 g ml-1 dextran. In isotonic quick-release experiments 0.025 g ml-1 dextran did not influence maximal shortening velocity (Vmax) and relative stiffness, whereas 0.1 g ml-1 markedly increased stiffness and decreased Vmax to about 27%. Vanadate induced relaxation in the activated muscle (pCa 4.5) both in the absence and presence (0.1 g ml-1) of dextran and increased the rate of relaxation (pCa 9) at 0.1 g ml-1 dextran. The isometric rate of crossbridge turnover, as reflected by the energetic tension cost and the rate of relaxation, was decreased at all degrees of osmotic compression. Crossbridge turnover rate during shortening (Vmax) was unaffected at an osmotic compression of 12% (width) but was decreased at higher compression (32%).

U2 - 10.1007/BF01753991

DO - 10.1007/BF01753991

M3 - Article

VL - 8

SP - 151

EP - 160

JO - Journal of Muscle Research and Cell Motility

T2 - Journal of Muscle Research and Cell Motility

JF - Journal of Muscle Research and Cell Motility

SN - 0142-4319

IS - 2

ER -