Increased Ca2+ and myosin phosphorylation, but not calmodulin activity in sensitized airway smooth muscles

1995 ◽  
Vol 269 (6) ◽  
pp. 1-1
Author(s):  
He Jiang ◽  
Kang Rao ◽  
Xueliang Liu ◽  
Gang Liu ◽  
Newman L. Stephans
Keyword(s):  
Light Chain ◽  
Myosin Light Chain ◽  
Smooth Muscles ◽  
Ragweed Pollen ◽  
Myosin Light Chain Phosphorylation ◽  
Myosin Phosphorylation

Page L739: He Jiang, Kang Rao, Xueliang Liu, Gang Liu, and Newman L. Stephans. “Increased Ca2+ and myosin phosphorylation, but not calmodulin activity in sensitized airway smooth muscles.” This title is incorrect and conveys the opposite meaning of the article. The correct title should read: “Intracellular Ca2+, myosin light chain phosphorylation, and calmodulin activity in ragweed pollen-sensitized airway smooth muscles.”

Increased Ca2+ and myosin phosphorylation, but not calmodulin activity in sensitized airway smooth muscles

1995 ◽  
Vol 269 (1) ◽  
pp. L135-L135
Author(s):  
He Jiang ◽  
Kang Rao ◽  
Xueliang Liu ◽  
Gang Liu ◽  
Newman L. Stephans
Keyword(s):  
Light Chain ◽  
Myosin Light Chain ◽  
Smooth Muscles ◽  
Ragweed Pollen ◽  
Myosin Light Chain Phosphorylation ◽  
Myosin Phosphorylation

Page L739: He Jiang, Kang Rao, Xueliang Liu, Gang Liu, and Newman L. Stephans. “Increased Ca2+ and myosin phosphorylation, but not calmodulin activity in sensitized airway smooth muscles.” This title is incorrect and conveys the opposite meaning of the article. The correct title should read: “Intracellular Ca2+, myosin light chain phosphorylation, and calmodulin activity in ragweed pollen-sensitized airway smooth muscles.”

Isoproterenol attenuates myosin phosphorylation and contraction of tracheal muscle

1989 ◽  
Vol 66 (5) ◽  
pp. 2017-2022 ◽  
Author(s):  
K. Obara ◽  
P. de Lanerolle
Keyword(s):  
Light Chain ◽  
Myosin Light Chain ◽  
Isometric Force ◽  
Smooth Muscles ◽  
Inhibitory Effect ◽  
Isometric Tension ◽  
Myosin Light Chain Phosphorylation ◽  
Response Curves ◽  
Shortening Velocity ◽  
Myosin Phosphorylation

The effects of isoproterenol on isometric force, unloaded shortening velocity, and myosin phosphorylation were examined in thin muscle bundles (0.1–0.2 mm diam) dissected from lamb tracheal smooth muscle. Methacholine (10(-6) M) induced rapid increases in isometric force and in phosphorylation of the 20,000-Da myosin light chain. Myosin phosphorylation remained elevated during steady-state maintenance of isometric force. The shortening velocity peaked at 15 s after stimulation with methacholine and then declined to approximately 45% of the maximal value by 3 min. Isoproterenol pretreatment inhibited methacholine-stimulated myosin light chain phosphorylation, shortening velocity, and force during the early stages of force generation. However, the inhibitory effect of isoproterenol on force and myosin phosphorylation is proportionally greater than that on shortening velocity. Isoproterenol pretreatment also caused a rightward non-parallel shift in the methacholine dose-response curves for both isometric tension and myosin light chain phosphorylation. These data demonstrate that isoproterenol attenuates the contractile properties of airway smooth muscles by affecting the rate and extent of myosin light chain phosphorylation, perhaps through a mechanism that involves the synergistic interaction of myosin light chain kinase phosphorylation and Ca2+ metabolism.

scholarly journals Cytoplasmic free calcium, myosin light chain phosphorylation, and force in phasic and tonic smooth muscle.

1988 ◽  
Vol 92 (6) ◽  
pp. 713-729 ◽  
Author(s):  
B Himpens ◽  
G Matthijs ◽  
A V Somlyo ◽  
T M Butler ◽  
A P Somlyo
Keyword(s):  
Smooth Muscle ◽  
Pulmonary Artery ◽  
Light Chain ◽  
Time Course ◽  
Myosin Light Chain ◽  
Muscle Tension ◽  
Smooth Muscles ◽  
Free Calcium ◽  
Myosin Light Chain Phosphorylation ◽  
Tonic Smooth Muscle

The time course of [Ca2+]i, tension, and myosin light chain phosphorylation were determined during prolonged depolarization with high K+ in intact tonic (rabbit pulmonary artery) and phasic (longitudinal layer of guinea pig ileum) smooth muscles. [Ca2+]i was monitored with the 340 nm/380 nm signal ratio of the fluorescent indicator fura-2. The fluorescence ratio had a similar time course in both muscle types during depolarization with 109 mM [K+]o; after a transient peak, there was a decline to 70% of its peak value in tonic smooth muscle, and to 60% in phasic smooth muscle. Tension, however, continued to increase in the pulmonary artery, while in the ileum it declined in parallel with the [Ca2+]i. On changing [K+]o from 109 to 20 mM, tension and [Ca2+]i either remained unchanged or declined in parallel in the pulmonary artery. Phosphorylation of the 20-kD myosin light chain, measured during stimulation of muscle strips with 109 mM [K+]o in another set of experiments, increased from 3% to a peak of 50% in the intact pulmonary artery, and then declined to a steady state value of 23%. In the intact ileum, a very rapid, early transient phosphorylation (up to 50%) at 2-3 s was seen. This transient declined by 30 s to a value that was close to the resting level (7%), while tension remained at 55% of its peak force. A quick release during maintained stimulation induced no detectable change in the [Ca2+]i in either type of smooth muscle. We discuss the possibility that the slowly rising tonic tension in pulmonary artery could be due to cooperativity between phosphorylated and nonphosphorylated crossbridges.

Effects of cGMP on [Ca2+]i, myosin light chain phosphorylation, and contraction in human myometrium

1991 ◽  
Vol 260 (4) ◽  
pp. C861-C867 ◽  
Author(s):  
R. A. Word ◽  
M. L. Casey ◽  
K. E. Kamm ◽  
J. T. Stull
Keyword(s):  
Smooth Muscle ◽  
Light Chain ◽  
Myosin Light Chain ◽  
Smooth Muscles ◽  
Smooth Muscle Relaxation ◽  
Human Myometrium ◽  
Myosin Light Chain Phosphorylation ◽  
Cyclic Monophosphate ◽  
Uterine Smooth Muscle ◽  
Spontaneous Contractions

Adenosine 3',5'-cyclic monophosphate (cAMP) is believed to be an important mediator of myometrial relaxation, and there is evidence to suggest that guanosine 3',5'-cyclic monophosphate (cGMP) is a mediator of smooth muscle relaxation in vascular and probably nonvascular tissues. To investigate the biochemical mechanisms involved in regulation of human myometrial contractility, we studied the effects of analogues of cAMP and cGMP, as well as activators of adenylate and guanylate cyclases, on uterine smooth muscle contractile activity. We found that myometrial smooth muscle cells in culture respond to analogues of cGMP and cAMP, as well as activators of guanylate cyclase, with a significant decrease in the resting and endothelin-induced increase in [Ca2+]i. Treatment of human uterine smooth muscle strips with sodium nitroprusside or isoproterenol results in diminished force and frequency of contraction as well as a decrease in the rate and extent of myosin light chain phosphorylation in spontaneous contractions of human myometrium. cGMP did not effect relaxation of endothelin-stimulated contractions of human myometrium, but the relaxation effects of cGMP were dramatic in precontracted bovine tracheal and human fetal aortic smooth muscles. Whereas cGMP and cAMP act to promote a decrease in the force and frequency of spontaneous contractions in human myometrium, this tissue is not as responsive to the actions of cyclic nucleotides as are other types of smooth muscle.

Chronic hypoxia modulates relations among calcium, myosin light chain phosphorylation, and force differently in fetal and adult ovine basilar arteries

2005 ◽  
Vol 99 (1) ◽  
pp. 120-127 ◽  
Author(s):  
Surya M. Nauli ◽  
James M. Williams ◽  
William T. Gerthoffer ◽  
William J. Pearce
Keyword(s):  
Light Chain ◽  
Myosin Light Chain ◽  
Cerebral Arteries ◽  
Cytosolic Calcium ◽  
Myosin Light Chain Phosphorylation ◽  
Postnatal Maturation ◽  
Myosin Phosphorylation ◽  
Age Related ◽  
Basilar Arteries ◽  
Nonpregnant Adult

The present study tests the hypothesis that age-related differences in contractility of cerebral arteries from hypoxic animals involve changes in myofilament Ca2+ sensitivity. Basilar arteries from term fetal and nonpregnant adult sheep maintained 110 days at 3,820 m were used in measurements of cytosolic calcium concentration ([Ca2+]i), myosin light chain phosphorylation, and contractile tensions induced by graded concentrations of K+ or serotonin (5-HT). Slopes relating [Ca2+]i to tension were similar in fetal (0.83 ± 0.07) and adult (1.02 ± 0.08) arteries for K+ contractions but were significantly greater for fetal (3.77 ± 0.64) than adult (2.00 ± 0.13) arteries for 5-HT contractions. For both K+ and 5-HT contractions, these relations were left shifted in fetal compared with adult arteries, indicating greater Ca2+ sensitivity in fetal arteries. In contrast, slopes relating [Ca2+]i and %myosin phosphorylation for K+ contractions were less in fetal (0.37 ± 0.08) than adult (0.81 ± 0.07) arteries, and the fetal curves were right shifted. For 5-HT contractions, the slope of the Ca2+-phosphorylation relation was similar in fetal (0.33 ± 0.09) and adult (0.33 ± 0.23) arteries, indicating that 5-HT depressed Ca2+-induced myosin phosphorylation in adult arteries. For slopes relating %myosin phosphorylation and tension, fetal values (K+: 1.52 ± 0.22, 5-HT: 7.66 ± 1.70) were less than adult values (K+: 2.13 ± 0.30, 5-HT: 8.29 ± 2.40) for both K+- and 5-HT-induced contractions, although again fetal curves were left shifted relative to the adult. Thus, in hypoxia-acclimatized basilar arteries, a downregulated ability of Ca2+ to promote myosin phosphorylation is offset by an upregulated ability of phosphorylated myosin to produce force yielding an increased fetal myofilament Ca2+ sensitivity. Postnatal maturation reprioritizes the mechanisms regulating hypoxic contractility through changes in the source of activator Ca2+, the pathways governing myosin light chain phosphorylation, and its interaction with actin.

Sodium hydrosulfite contractions of smooth muscle are calcium and myosin phosphorylation independent

1998 ◽  
Vol 275 (5) ◽  
pp. L976-L982 ◽  
Author(s):  
Ming-Fu Yu ◽  
Isabelle Gorenne ◽  
Xiaoling Su ◽  
Robert S. Moreland ◽  
Michael I. Kotlikoff
Keyword(s):  
Smooth Muscle ◽  
Muscle Contraction ◽  
Light Chain ◽  
Myosin Light Chain ◽  
Hypoxic Pulmonary Vasoconstriction ◽  
Smooth Muscles ◽  
Smooth Muscle Contraction ◽  
Myosin Light Chain Phosphorylation ◽  
Sodium Hydrosulfite ◽  
Pulmonary Arterial

In an effort to further understand the processes underlying hypoxic pulmonary vasoconstriction, we examined the mechanism by which sodium hydrosulfite (Na2S2O4), a potent reducing agent and oxygen scavenger, induces smooth muscle contraction. In rat pulmonary arterial strips, sodium hydrosulfite (10 mM) induced contractions that were 65.9 ± 12.8% of the response to 60 mM KCl ( n = 9 segments). Contractions were not inhibited by nisoldipine (5 μM) or by repeated stimulation with caffeine (10 mM), carbonyl cyanide p-(trifluoromethoxy)phenylhydrazone (10 μM), or cyclopiazonic acid (10 μM), all of which eliminated responses to contractile agonists. Maximum force generation after exposure to sodium hydrosulfite was 0.123 ± 0.013 mN in the presence of 1.8 mM calcium and 0.127 ± 0.015 mN in the absence of calcium. Sodium hydrosulfite contractions in pulmonary arterial segments were not due to the generation of H2O2and occurred in the presence of chelerythrine (10 μM), which blocked phorbol ester contractions, and solution hyperoxygenation. Similar contractile responses were obtained in rat aortic and tracheal smooth muscles. Finally, contractions occurred in the complete absence of an increase in myosin light chain phosphorylation. Therefore sodium hydrosulfite-induced smooth muscle contraction is not specific to pulmonary arterial smooth muscle, is independent of calcium and myosin light chain phosphorylation, and is not mediated by either hypoxia or protein kinase C.

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