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(Circulation Research. 2004;94:1273.)
© 2004 American Heart Association, Inc.

Editorials

Cold-Induced Vasoconstriction

A Waltz Pairing Rho-Kinase Signaling and ₂-Adrenergic Receptor Translocation

Cleber E. Teixeira, R. Clinton Webb

From the Department of Physiology, Medical College of Georgia, Augusta, Ga.

Correspondence to Cleber E. Teixeira, Department of Physiology, Medical College of Georgia, 1120 Fifteenth Street, CA-3101, Augusta, GA 30912-3000. E-mail cteixeira@mail.mcg.edu

Key Words: vascular smooth muscle • Rho-kinase • microtubules • ₂-adenoreceptors

An extract of the first 250 words of the full text is provided, because this article has no abstract.

Advances made over the past few years have made us appreciate the critical roles of Rho-associated kinase (Rho-kinase/ROCK) in a bewildering variety of cellular and biological responses. Rho-kinase represents a downstream target for the low–molecular-weight G-protein, Rho, and is believed to transmit signals to cytoskeletal and regulatory proteins. In recent years, enormous progress has been made in understanding the role of this signaling pathway in regulating cellular movements, cell growth, and cell–cell interactions. Rho-kinase has been implicated in many cellular processes, such as stress fiber and focal adhesion formation, smooth muscle contraction, neurite retraction, and cell migration.^1,2

In addition to Ca²⁺-dependent increases in myosin light chain (MLC) phosphorylation for vascular contraction to occur, the concept of a Ca²⁺-sensitizing mechanism for the promotion of the phosphorylated state of MLC has become evident.³ Extensive studies demonstrate that the sustained contractile force in vascular smooth muscle preparations generated on agonist stimulation does not parallel intracellular Ca²⁺ levels. On exposure to an agonist, Ca²⁺ concentration in the cytosol peaks and then quickly drops to near-resting levels despite the maintenance of contractile force. Further, tonic force generation in many vascular preparations persists in Ca²⁺-free media, further implicating an increase in Ca²⁺ sensitivity of the contractile apparatus, or the activation of a Ca²⁺-independent mechanism.^4,5 This phenomenon has been termed agonist-induced force enhancement, or Ca²⁺ sensitization, and several mechanisms have been proposed.^3,6 Although the signaling pathway(s) for Ca²⁺ sensitization have not been fully elucidated, the most proposed mechanism converges on an inhibition of . . . [Full Text of this Article]