Effects of the Na ionophore monensin on the contractile response and the movements of monovalent cations in the vascular smooth muscle of rabbit aorta

1982 ◽  
Vol 321 (2) ◽  
pp. 140-144 ◽  
Author(s):  
Hiroshi Ozaki ◽  
Tadashi Kishimoto ◽  
Hideaki Karaki ◽  
Norimoto Urakawa
1984 ◽  
Vol 100 (3-4) ◽  
pp. 299-307 ◽  
Author(s):  
H. Ozaki ◽  
T. Kishimoto ◽  
S. Chihara ◽  
H. Umeno ◽  
N. Urakawa

1981 ◽  
Vol 72 (4) ◽  
pp. 323-329 ◽  
Author(s):  
Alan S. Fairhurst ◽  
Gerald Kent ◽  
Ralph E. Purdy

2001 ◽  
Vol 90 (2) ◽  
pp. 665-669 ◽  
Author(s):  
Jorge Brieva ◽  
Adam Wanner

The purpose of the present study was to determine the responsiveness of airway vascular smooth muscle (AVSM) as assessed by airway mucosal blood flow (Q˙aw) to inhaled methoxamine (α1-agonist; 0.6–2.3 mg) and albuterol (β2-agonist; 0.2–1.2 mg) in healthy [ n = 11; forced expiratory volume in 1 s, 92 ± 4 (SE) % of predicted] and asthmatic ( n = 11, mean forced expiratory volume in 1 s, 81 ± 5%) adults. Mean baseline values for Q˙aw were 43.8 ± 0.7 and 54.3 ± 0.8 μl · min−1· ml−1of anatomic dead space in healthy and asthmatic subjects, respectively ( P < 0.05). After methoxamine inhalation, the maximal mean change in Q˙aw was −13.5 ± 1.0 μl · min−1· ml−1in asthmatic and −7.1 ± 2.1 μl · min−1· ml−1in healthy subjects ( P < 0.05). After albuterol, the mean maximal change in Q˙aw was 3.0 ± 0.8 μl · min−1· ml−1in asthmatic and 14.0 ± 1.1 μl · min−1· ml−1in healthy subjects ( P < 0.05). These results demonstrate that the contractile response of AVSM to α1-adrenoceptor activation is enhanced and the dilator response of AVSM to β2-adrenoceptor activation is blunted in asthmatic subjects.


1994 ◽  
Vol 72 (8) ◽  
pp. 919-936 ◽  
Author(s):  
Michael P. Walsh

Vascular smooth muscle tone is regulated primarily by the sarcoplasmic free Ca2+ concentration, which determines the level of myosin phosphorylation. Stimulation of the muscle results in an increase in free [Ca2+], whereupon Ca2+ binds to calmodulin, inducing a conformational change enabling calmodulin to interact with and activate myosin light chain kinase. The active Ca2+∙calmodulin∙myosin light chain kinase complex catalyses the phosphorylation of serine-19 of the two 20-kDa light chains of myosin; this triggers cross-bridge cycling and the development of force. Relaxation follows restoration of free [Ca2+] to the resting level, whereupon calmodulin dissociates from myosin light chain kinase, which is thereby inactivated, and myosin is dephosphorylated by myosin light chain phosphatase and remains detached from actin. Overwhelming evidence now exists in favour of the central role of myosin phosphorylation–dephosphorylation in smooth muscle contraction–relaxation. However, considerable evidence supports the existence of additional, secondary mechanisms that can modulate the contractile state of smooth muscle either by altering the Ca2+ sensitivity of the contractile response or otherwise modulating one of the molecular events occurring downstream of the Ca2+ signal, e.g., the interaction of phosphorylated myosin heads with actin. The interplay of several regulatory elements confers on the contractile response of vascular smooth muscle the high degree of flexibility and adaptability required for the effective regulation of blood pressure.Key words: calcium, myosin, protein kinases, protein phosphatases, signal transduction, regulation of contraction, caldesmon, calponin.


2003 ◽  
Vol 40 (6) ◽  
pp. 520-530 ◽  
Author(s):  
Elena B. Okon ◽  
Tania Szado ◽  
Ismail Laher ◽  
Bruce McManus ◽  
Cornelis van Breemen

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