Ca2+ sources mobilized by α1-receptor activation in vascular smooth muscle

1985 ◽  
Vol 68 (s10) ◽  
pp. 47s-50s ◽  
Author(s):  
P. Leijten ◽  
C. Cauvin ◽  
N. Lodge ◽  
K. Saida ◽  
C. Van Breemen
Keyword(s):  
Smooth Muscle ◽  
Sarcoplasmic Reticulum ◽  
Vascular Smooth Muscle ◽  
External Surface ◽  
Receptor Activation ◽  
Tension Development ◽  
Intracellular Store ◽  
Phasic Component

1. We propose the following model of Ca2+ mobilization by noradrenaline in vascular smooth muscle. Upon receptor occupation Ca2+ from a labile small intracellular store on the inner plasmalemma is released. This Ca2+ does not function as activator Ca2+ but triggers Ca2+ release from the sarcoplasmic reticulum (Ca2+-induced Ca2+ release). 2. Simultaneously Ca2+ from an extracellularly bound store (on the external surface of the plasmalemma) is dislodged, which enters the cell through receptor linked channels. 3. These processes are responsible for the early ‘phasic’ component of the noradrenaline contraction. In addition, Ca2+ from the free extracellular Ca2+ pool enters through receptor operated channels, supporting the maintained tension development.

scholarly journals Effects of Hyperglycemia on Vascular Smooth Muscle Ca2+Signaling

2017 ◽  
Vol 2017 ◽  
pp. 1-16 ◽  
Author(s):  
Nahed El-Najjar ◽  
Rashmi P. Kulkarni ◽  
Nancy Nader ◽  
Rawad Hodeify ◽  
Khaled Machaca
Keyword(s):  
Insulin Resistance ◽  
Smooth Muscle ◽  
Sarcoplasmic Reticulum ◽  
Vascular Smooth Muscle ◽  
Complex Disease ◽  
Prolonged Exposure ◽  
In Vitro System ◽  
A7r5 Cells

Diabetes is a complex disease that is characterized with hyperglycemia, dyslipidemia, and insulin resistance. These pathologies are associated with significant cardiovascular implications that affect both the macro- and microvasculature. It is therefore important to understand the effects of various pathologies associated with diabetes on the vasculature. Here we directly test the effects of hyperglycemia on vascular smooth muscle (VSM) Ca2+signaling in an isolated in vitro system using the A7r5 rat aortic cell line as a model. We find that prolonged exposure of A7r5 cells to hyperglycemia (weeks) is associated with changes to Ca2+signaling, including most prominently an inhibition of the passive ER Ca2+leak and the sarcoplasmic reticulum Ca2+-ATPase (SERCA). To translate these findings to the in vivo condition, we used primary VSM cells from normal and diabetic subjects and find that only the inhibition of the ER Ca2+leaks replicates in cells from diabetic donors. These results show that prolonged hyperglycemia in isolation alters the Ca2+signaling machinery in VSM cells. However, these alterations are not readily translatable to the whole organism situation where alterations to the Ca2+signaling machinery are different.

scholarly journals Angiotensin II type 2 receptor activation induces RhoA inhibition through Phosphorylation of its Serine 188 in Vascular Smooth Muscle Cells

2006 ◽  
Vol 20 (4) ◽  
Author(s):  
Malvyne Rolli‐Derkinderen ◽  
Christophe Guilluy ◽  
Laurent Loufrani ◽  
Daniel Henrion ◽  
Gervaise Loirand ◽  
...  
Keyword(s):  
Smooth Muscle ◽  
Angiotensin Ii ◽  
Vascular Smooth Muscle ◽  
Smooth Muscle Cells ◽  
Vascular Smooth Muscle Cells ◽  
Muscle Cells ◽  
Receptor Activation

Dependence of stress on cross-bridge phosphorylation in vascular smooth muscle

1989 ◽  
Vol 256 (1) ◽  
pp. C96-C100 ◽  
Author(s):  
P. H. Ratz ◽  
C. M. Hai ◽  
R. A. Murphy
Keyword(s):  
Smooth Muscle ◽  
Steady State ◽  
Vascular Smooth Muscle ◽  
Light Chain ◽  
Phorbol Esters ◽  
Receptor Activation ◽  
Bay K 8644 ◽  
Cross Bridge ◽  
Cross Bridges ◽  
State Stress

Cross-bridge phosphorylation associated with agonist-stimulated contraction of vascular smooth muscle is often transiently elevated. Such observations led to the concept that phosphorylation of the 20-kDa myosin regulatory light chain (Mp) was required for initial activation and cross-bridge cycling but might not be necessary for steady-state maintenance of stress in the latch state. The possibility that stress maintenance is not regulated by phosphorylation has received some experimental support in contractions induced by phorbol esters and the calcium channel activator BAY K 8644 in which significant increases in Mp were not detected. Our aim was to test the hypothesis that phosphorylation is both necessary and sufficient for activation and for maintenance of steady-state stress. Activation of swine carotid media using agents that bypass receptor activation and elevate Ca2+ influx without mobilizing intracellular Ca2+ stores (BAY K 8644 and ionomycin) produced monotonic increases in both stress and Mp. Transient initial peaks in Mp were absent. Steady-state stress induced by both receptor- and nonreceptor-mediated activation was dependent on small increases in Mp. Increases in Mp greater than 0.3 mol Pi/mol myosin light chain had small effects on stress but produced large increases in the maximum rate of cross-bridge cycling at zero load (Vo). The experimentally determined dependence of stress on Mp was quantitatively predicted by our working hypothesis. This model proposes that Ca2+-stimulated cross-bridge phosphorylation is obligatory for cross-bridge attachment. However, dephosphorylation of attached cross bridges to form noncycling "latch bridges" allows stress maintenance with reduced Mp and cycling.

Role of Sarcoplasmic Reticulum in the Contractile Function of Vascular Smooth Muscle as Studied by 2,5-Di-(Tert-Butyl)-1,4-Benzohydroquinone

Neurosignals ◽  
1992 ◽  
Vol 1 (4) ◽  
pp. 182-193 ◽  
Author(s):  
Hiroyuki Shimamoto ◽  
Ingrid L.A. Majarais ◽  
Yoriko Shimamoto ◽  
Chiu-Yin Kwan ◽  
Edwin E. Daniel
Keyword(s):  
Smooth Muscle ◽  
Sarcoplasmic Reticulum ◽  
Vascular Smooth Muscle ◽  
Contractile Function ◽  
Tert Butyl

The sarcoplasmic reticulum Ca2+ store arrangement in vascular smooth muscle

Cell Calcium ◽  
2009 ◽  
Vol 46 (5-6) ◽  
pp. 313-322 ◽  
Author(s):  
Richard D. Rainbow ◽  
Debbi MacMillan ◽  
John G. McCarron
Keyword(s):  
Smooth Muscle ◽  
Sarcoplasmic Reticulum ◽  
Vascular Smooth Muscle

Influence of ATP on sarcoplasmic reticulum function of vascular smooth muscle

1982 ◽  
Vol 242 (3) ◽  
pp. C242-C249 ◽  
Author(s):  
G. D. Ford ◽  
M. L. Hess
Keyword(s):  
Smooth Muscle ◽  
Sarcoplasmic Reticulum ◽  
Vascular Smooth Muscle ◽  
Calcium Transport ◽  
Calcium Uptake ◽  
Specific Activity ◽  
Substrate Inhibition ◽  
Uptake Activity ◽  
Active Calcium ◽  
Active Preparation

A vesicular fraction isolated from bovine aorta and enriched in fragmented sarcoplasmic reticulum (FSR) exhibited active calcium transport and ATPase activity. By use of a hypotonic NaHCO3 extraction solution, an active preparation was isolated that retained activity for up to 4 days. A small but significant (P less than 0.05) Ca2+-stimulated, Mg2+-dependent ATPase associated with calcium transport was demonstrated with a specific activity of 0.33 mumol inorganic phosphate (Pi).mg-1.min-1. The basal Mg2+ ATPase demonstrated Michaelis-Menten kinetics [Km(Mg2+-ATP) = 0.44 +/- 0.01 X 10(-3) M; Vmax = 2.22 +/- 0.01 mumolPi.mg-1.min-1]. The Ca2+-stimulated, Mg2+-ATPase demonstrated apparent substrate inhibition (Ks approximately 10 mM) with no evidence for end-product (ADP) or excess added Ca2+ contributing to this inhibition. Oxalate-supported active calcium uptake velocities also exhibited quantitatively similar substrate inhibition. These results suggest that FSR from vascular smooth muscle contains either two enzymes or one enzyme with two isomeric forms, one of which is associated with the calcium uptake activity of this structure and the other of unknown function.

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