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Ca2+ sequestration as a determinant of chaos and mixed-mode dynamics in agonist-induced vasomotion

Griffith, T. M. and Edwards, David Hughes 1997. Ca2+ sequestration as a determinant of chaos and mixed-mode dynamics in agonist-induced vasomotion. American Journal of Physiology - Heart and Circulatory Physiology 272 (4 pt 2) , H1696-H1709.

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Abstract

We have investigated the contribution of smooth muscle Ca2+ stores to chaotic vasomotion in isolated rabbit ear resistance arteries. In preparations constricted by histamine, exposure to cyclopiazonic acid (CPA) and thapsigargin (TSG), which inhibit the Ca2+-adenosinetriphosphatase (ATPase) pump of the sarcoplasmic reticulum, first induced then abolished highly characteristic mixed-mode oscillatory behavior. The fractal dimension of the vasomotion, which reflects the minimum number of contributing dynamic variables, remained between 2 and 4 until the point at which oscillations disappeared completely. By contrast, ryanodine, which attenuates Ca2+-induced Ca2+ release, decreased the fractal dimension of the responses to <2 in a graded concentration-dependent fashion by selectively suppressing a slow subcomponent of the overall rhythmic activity. CPA-associated oscillations were insensitive to ryanodine but could be abolished by verapamil and modulated in an inhibitory or stimulatory fashion by charybdotoxin, which blocks Ca2+-activated K+ channels, and by ouabain, which blocks the Na+-K+-ATPase. We conclude that there is nonlinear cross talk between CPA/TSG-sensitive Ca2+ stores and a membrane oscillator that regulates Ca2+ influx and that the kinetics of Ca2+ uptake by the CPA/TSG-sensitive pool can be distinguished dynamically from the kinetics of Ca2+ release from its ryanodine-sensitive subcomponent.

Item Type: Article
Date Type: Publication
Status: Published
Schools: Medicine
Subjects: R Medicine > R Medicine (General)
Publisher: American Physiological Society
ISSN: 0363-6135
Related URLs:
Last Modified: 04 Jun 2017 08:04
URI: http://orca-mwe.cf.ac.uk/id/eprint/72378

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