ISSN:
1432-2013
Keywords:
Vascular smooth muscle
;
Calcium
;
Smooth muscle mechanics
Source:
Springer Online Journal Archives 1860-2000
Topics:
Medicine
Notes:
Abstract Stimulation of swine carotid artery medial fibers with 110 mM KCl at 37°C results in increases in myosin light chain (MLC) phosphorylation levels and maximal shortening velocity (V o) during the period of stress development. During the period of stress maintenance, MLC phosphorylation levels andV o are not maintained, but fall to suprabasal levels, resulting in a correlation between MLC phosphorylation andV o and suggesting that MLC phosphorylation regulatesV o. This study identifies other conditions of KCl depolarization of swine carotid medial fibers in which this relationship between MLC phosphorylation andV o is altered. A decrease in temperature from 37° to 23°C results in a similar magnitude of stress maintenance in response to 110 mM KCl and similar levels of MLC phosphorylation, but a reduction inV o by approximately 50%. This differential effect of temperature onV o and MLC phosphorylation results in a downward shift in the slope of the regression line describing the relationship between these two parameters. Decreasing [KCl] to 40 mM in the stimulating solution results again in similar magnitudes of miantained stress. MLC phosphorylation levels are not transient, but maintained at a constant value andV o is transient at levels approximately 50% of those at 110 mM KCl at 37°C. This results in a complete lack of correlation between MLC phosphorylation andV o. Thus stress can be developed to equal magnitudes under differing activation conditions with dissimilar patterns of MLC phosphorylation andV o. Therefore, there is not a strict relationship between MLC phosphorylation andV o in all cases.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00581343
Permalink
