Unusual [Ca2+] dependence of vascular smooth muscle cell shortening velocity

Author:

Dougherty T. J.1,Driska S. P.1

Affiliation:

1. Physiology Department, Temple University School of Medicine, Philadelphia, Pennsylvania 19140.

Abstract

The relationship between unloaded shortening velocity and Ca2+ concentration was determined for hog carotid arterial smooth muscle cells, freshly isolated by digestion with papain. Cells were exposed to various [Ca2+] for 60 s at 37 degrees C and then stimulated with 10 microM histamine. Cell length was measured by a video analysis system. Shortening velocity was expressed as an exponential rate constant by fitting the cell lengths to the following equation: length = Lmin + (Lmax-Lmin)exp[-v (time-latency)], where Lmax is length before contraction, Lmin is shortest length reached, time is time elapsed after addition of agonist, latency is time from addition of agonist until contraction starts, and v is the exponential rate constant (s-1). Cells shortened substantially, usually reaching one-fourth to one-third of their initial length within 1 min. Shortening velocities of the cells were much faster than published values of maximum shortening velocity in muscle strips from this same tissue. At 1.6 mM Ca2+, v was 0.173 +/- 0.015 s-1. When Ca2+ was increased to 5 or 10 mM, v was not significantly different. However, when Ca2+ was decreased to 0.5 and 0.16 mM, v increased to 0.288 and 0.258 s-1, respectively. The difference between 0.5 and 1.6 mM was significant. The unexpected increase in shortening velocity at low Ca2+ was also seen when 10 mM caffeine was used as a stimulus: v at 1.6 mM Ca2+ was 0.156 s-1, whereas v at 0.16 mM Ca2+ was 0.272 s-1. The high shortening velocities we measured suggest that measurements made on multicellular tissues seriously underestimate the potential shortening velocity of isolated individual cells.

Publisher

American Physiological Society

Subject

Cell Biology,Physiology

Cited by 3 articles. 订阅此论文施引文献 订阅此论文施引文献,注册后可以免费订阅5篇论文的施引文献,订阅后可以查看论文全部施引文献

1. Maximum shortening velocity of lymphatic muscle approaches that of striated muscle;American Journal of Physiology-Heart and Circulatory Physiology;2013-11-15

2. Mechanical strain increases velocity and extent of shortening in cultured airway smooth muscle cells;American Journal of Physiology-Lung Cellular and Molecular Physiology;1999-08-01

3. A method for isolating adult and neonatal airway smooth muscle cells and measuring shortening velocity;Journal of Applied Physiology;1999-01-01

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