Alteration of microtubule polymerization modulates arteriolar vasomotor tone

• Published in: American journal of physiology. Heart and circulatory physiology 1999-07, Vol.277 (1), p.H100-H106
• Main Authors: Platts, Steven H, Falcone, Jeff C, Holton, William T, Hill, Michael A, Meininger, Gerald A
• Format: Article
• Language: English
• ISSN: 0363-6135; 1522-1539
• DOI: 10.1152/ajpheart.1999.277.1.h100

1  Cardiovascular Research Institute and Department of Medical Physiology, Texas A&M University System Health Science Center, College Station, Texas 77843-1114; 2  Department of Physiology and Biophysics, School of Medicine, University of Louisville, Louisville, Kentucky 40292; and 3  Department of Human Biology and Movement Science, Royal Melbourne Institute of Technology University, Bundoora, Victoria 3083, Australia Microtubules are important cytoskeletal elements that have been shown to play a major role in many cellular processes because of their mechanical properties and/or their participation in various cell signaling pathways. We tested the hypothesis that depolymerization of microtubules would alter vascular smooth muscle (VSM) tone and hence contractile function. In our studies, isolated cremaster arterioles exhibited significant vasoconstriction that developed over a 20- to 40-min period when they were treated with microtubule depolymerizing drugs colchicine (10 µM), nocodazole (10 µM), or demecolcine (10 µM). Immunofluorescent labeling of microtubules in cultured rat VSM revealed that both colchicine and nocodazole caused microtubule depolymerization over a similar time course. The vasoconstriction was maintained over a wide range of intraluminal pressures (30-170 cmH 2 O). The increased tone was not affected by endothelial denudation, suggesting that it was due to an effect on VSM. Microtubule depolymerization with demecolcine or colchicine had no effect on VSM intracellular Ca 2+ concentration ([Ca 2+ ] i ). These data indicate that microtubules significantly interact with processes leading to the expression of vasomotor tone. The mechanism responsible for the effect of microtubules on vasomotor tone appears to be independent of both the endothelium and an increase in VSM [Ca 2+ ] i . cytoskeleton; tubulin; vascular smooth muscle; endothelium; vasoconstriction; microcirculation