Comparative effects of adenosine and nifedipine in rabbit vascular smooth muscle

1983 ◽  
Vol 61 (9) ◽  
pp. 1057-1062 ◽  
Author(s):  
M. A. Young ◽  
G. F. Merrill
Keyword(s):  
Smooth Muscle ◽  
Vascular Smooth Muscle ◽  
Calcium Channel ◽  
Channel Blocker ◽  
Reactive Hyperemia ◽  
Channel Blockers ◽  
Vascular Relaxation ◽  
Negative Interaction

The calcium channel blocker nifedipine attenuates the coronary response to adenosine infusion and reactive hyperemia in dogs. Other evidence indicates adenosine may dilate vascular smooth muscle with a mechanism similar to the calcium channel blockers. In isolated rabbit femoral arterial rings, we studied the interaction of adenosine and nifedipine in mediating vascular relaxation. We also compared the actions of adenosine and nifedipine in relaxing norepinephrine- and K+-stimulated tension, and Ca2+-free contractions in an effort to elucidate differences in the specificity of the two agents. Nifedipine (10–25 μg/L) was without effect on adenosine-mediated relaxation of femoral arteries. Adenosine exhibited a greater ability to relax NE-induced contractions and contractions in Ca2+-free medium than did nifedipine. Conversely, nifedipine attenuated K+-induced contractions more effectively than adenosine. These results suggest that adenosine and nifedipine have different cellular actions and that part of adenosine-mediated relaxation may operate intracellularly. Furthermore, the negative interaction of nifedipine and adenosine in vivo suggests that these agents might act differently in an in vitro setting.

Mg2+–Ca2+ interaction in contractility of vascular smooth muscle: Mg2+ versus organic calcium channel blockers on myogenic tone and agonist-induced responsiveness of blood vessels

1987 ◽  
Vol 65 (4) ◽  
pp. 729-745 ◽  
Author(s):  
B. M. Altura ◽  
B. T. Altura ◽  
A. Carella ◽  
A. Gebrewold ◽  
T. Murakawa ◽  
...  
Keyword(s):  
Smooth Muscle ◽  
Vascular Smooth Muscle ◽  
Blood Vessels ◽  
Divalent Cations ◽  
Smooth Muscles ◽  
In Vivo Studies ◽  
Channel Blockers ◽  
Arterial Blood

Contractility of all types of invertebrate and vertebrate muscle is dependent upon the actions and interactions of two divalent cations, viz., calcium (Ca2+) and magnesium (Mg2+) ions. The data presented and reviewed herein contrast the actions of several organic Ca2+ channel blockers with the natural, physiologic (inorganic) Ca2+ antagonist, Mg2+, on microvascular and macrovascular smooth muscles. Both direct in vivo studies on microscopic arteriolar and venular smooth muscles and in vitro studies on different types of blood vessels are presented. It is clear from the studies done so far that of all Ca2+ antagonists examined, only Mg2+ has the capability to inhibit myogenic, basal, and hormonal-induced vascular tone in all types of vascular smooth muscle. Data obtained with verapamil, nimopidine, nitrendipine, and nisoldipine on the microvasculature are suggestive of the probability that a heterogeneity of Ca2+ channels, and of Ca2+ binding sites, exists in different microvascular smooth muscles; although some appear to be voltage operated and others, receptor operated, they are probably heterogeneous in composition from one vascular region to another. Mg2+ appears to act on voltage-, receptor-, and leak-operated membrane channels in vascular smooth muscle. The organic Ca2+ channel blockers do not have this uniform capability; they demonstrate a selectivity when compared with Mg2+. Mg2+ appears to be a special kind of Ca2+ channel antagonist in vascular smooth muscle. At vascular membranes it can (i) block Ca2+ entry and exit, (ii) lower peripheral and cerebral vascular resistance, (iii) relieve cerebral, coronary, and peripheral vasospasm, and (iv) lower arterial blood pressure. At micromolar concentrations (i.e., 10–100 μM), Mg2+ can cause significant vasodilatation of intact arterioles and venules in all regional vasculatures so far examined. Although Mg2+ is three to five orders of magnitude less potent than the organic Ca2+ channel blockers, it possesses unique and potentially useful Ca2+ antagonistic properties.

Evidence for Des-Tyr1-D-Ala2-leucine5-enkephalinamide calcium agonist activity in vascular smooth muscle

1987 ◽  
Vol 65 (2) ◽  
pp. 120-123 ◽  
Author(s):  
Michael B. Given ◽  
Gary E. Sander ◽  
Thomas D. Giles
Keyword(s):  
Smooth Muscle ◽  
Vascular Smooth Muscle ◽  
Calcium Channel ◽  
Receptor Antagonist ◽  
Calcium Influx ◽  
Pressor Response ◽  
Significant Inhibition ◽  
Conscious Dogs

Intravenous administration of the enkephalin analog Des-Tyr1-D-Ala2-Leu5-enkephalinamide (DTALE) to conscious dogs produces a pressor response that is not inhibited by naloxone. In an attempt to explain this observed pressor activity in vivo, the effect of DTALE on vascular smooth muscle was investigated in vitro. DTALE was found to contract rat thoracic aorta strips in a dose-dependent and naloxone-insensitive manner. Pretreatment with reserpine (5 mg/kg) or prazosin was without significant effect. However, a significant inhibition was obtained with cyproheptadine (p < 0.001, n = 5), a 5-hydroxytryptamine (5-HT) receptor antagonist that also has calcium channel blocking activity. Treatment with ketanserin (0.1 μM), a selective 5-HT2-receptor antagonist, had no effect. Reduction of the extracellular calcium concentration from 1.6 to 1.2 mM or 0.8 mM significantly diminished DTALE activity (1.2 mM, p < 0.025; 0.8 mM, p < 0.01; n = 3). Pretreatment with the calcium channel antagonists verapamil (0.1 μM) and nitrendipine (0.05 μM) significantly inhibited DTALE activity (p < 0.001 for both treatments). DTALE also exhibited increased potency in partially depolarized smooth muscle preparations. These results suggest that DTALE may produce vasoconstriction by inducing or facilitating calcium influx. This activity upon arterial vascular strips may provide explanation for the observed pressor response in chronically instrumented conscious dogs.

Stress causes decrease in vascular relaxation linked with altered phosphorylation of heat shock proteins

2000 ◽  
Vol 279 (2) ◽  
pp. R492-R498 ◽  
Author(s):  
Leslie C. Fuchs ◽  
Ararat D. Giulumian ◽  
Louis Knoepp ◽  
Walter Pipkin ◽  
Mary Dickinson ◽  
...  
Keyword(s):  
Smooth Muscle ◽  
Heat Shock ◽  
Vascular Smooth Muscle ◽  
Cyclic Nucleotide ◽  
Cellular Stress ◽  
Dependent Manner ◽  
Vascular Relaxation ◽  
Behavioral Stress

Cyclic nucleotide-dependent vascular relaxation is associated with increases in the phosphorylation of a small heat shock protein (HSP), HSP20. An increase in phosphorylation of another small HSP, HSP27, is associated with impaired cyclic nucleotide-dependent vascular relaxation. Expression of HSPs is altered by exposure to several types of cellular stress in vitro. To determine if behavioral stress in vivo alters vascular expression and phosphorylation of the small HSPs and cyclic nucleotide-dependent vascular relaxation, borderline hypertensive rats were stressed by restraint and exposure to air-jet stress 2 h/day for 10 days or remained in their home cage. Stress impaired relaxation of aorta to forskolin, which activates adenylyl cyclase, and sodium nitroprusside, which activates guanylyl cyclase. This was associated with an increase in the aortic expression and phosphorylation of HSP27, which was localized to the vascular smooth muscle, but a decrease in the amount of phosphorylated (P)-HSP20. To determine if P-HSP27 inhibits phosphorylation of HSP20, P-HSP27 was added to a reaction mixture containing recombinant HSP20 and the catalytic subunit of cAMP-dependent protein kinase. P-HSP27 inhibited phosphorylation of HSP20 in a concentration-dependent manner. These data demonstrate that P-HSP27 can inhibit phosphorylation of HSP20. The increase in P-HSP27 and decrease in P-HSP20 were associated with reduced cyclic nucleotide-dependent vascular smooth muscle relaxation in response to behavioral stress in vivo, an effect similar to that observed previously in response to cellular stress in vitro.

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 Induction of cyclooxygenase-2 in rat vascular smooth muscle cells in vitro and in vivo.

1994 ◽  
Vol 269 (11) ◽  
pp. 8504-8509
Author(s):  
K.A. Pritchard ◽  
M.K. O'Banion ◽  
J.M. Miano ◽  
N. Vlasic ◽  
U.G. Bhatia ◽  
...  
Keyword(s):  
Smooth Muscle ◽  
Vascular Smooth Muscle ◽  
Smooth Muscle Cells ◽  
Vascular Smooth Muscle Cells ◽  
Muscle Cells ◽  
Cyclooxygenase 2

Angiotensin II modulates frizzled-2 receptor expression in rat vascular smooth muscle cells

2005 ◽  
Vol 108 (6) ◽  
pp. 523-530 ◽  
Author(s):  
Giovanna CASTOLDI ◽  
Serena REDAELLI ◽  
Willy M. M. van de GREEF ◽  
Cira R. T. di GIOIA ◽  
Giuseppe BUSCA ◽  
...  
Keyword(s):  
Smooth Muscle ◽  
Angiotensin Ii ◽  
Vascular Smooth Muscle ◽  
Smooth Muscle Cells ◽  
Vascular Smooth Muscle Cells ◽  
Muscle Cells ◽  
Ang Ii ◽  
Aortic Smooth Muscle

Ang II (angiotensin II) has multiple effects on vascular smooth muscle cells through the modulation of different classes of genes. Using the mRNA differential-display method to investigate gene expression in rat aortic smooth muscle cells in culture in response to 3 h of Ang II stimulation, we observed that Ang II down-regulated the expression of a member of the family of transmembrane receptors for Wnt proteins that was identified as Fzd2 [Fzd (frizzled)-2 receptor]. Fzds are a class of highly conserved genes playing a fundamental role in the developmental processes. In vitro, time course experiments demonstrated that Ang II induced a significant increase (P<0.05) in Fzd2 expression after 30 min, whereas it caused a significant decrease (P<0.05) in Fzd2 expression at 3 h. A similar rapid up-regulation after Ang II stimulation for 30 min was evident for TGFβ1 (transforming growth factor β1; P<0.05). To investigate whether Ang II also modulated Fzd2 expression in vivo, exogenous Ang II was administered to Sprague–Dawley rats (200 ng·kg−1 of body weight·min−1; subcutaneously) for 1 and 4 weeks. Control rats received normal saline. After treatment, systolic blood pressure was significantly higher (P<0.01), whereas plasma renin activity was suppressed (P<0.01) in Ang II- compared with the saline-treated rats. Ang II administration for 1 week did not modify Fzd2 expression in aorta of Ang II-treated rats, whereas Ang II administration for 4 weeks increased Fzd2 mRNA expression (P<0.05) in the tunica media of the aorta, resulting in a positive immunostaining for fibronectin at this time point. In conclusion, our data demonstrate that Ang II modulates Fzd2 expression in aortic smooth muscle cells both in vitro and in vivo.

scholarly journals SIRT1 and FOXO Mediate Contractile Differentiation of Vascular Smooth Muscle Cells under Cyclic Stretch

2015 ◽  
Vol 37 (5) ◽  
pp. 1817-1829 ◽  
Author(s):  
Kai Huang ◽  
Zhi-Qiang Yan ◽  
Dan Zhao ◽  
Si-Guo Chen ◽  
Li-Zhi Gao ◽  
...  
Keyword(s):  
Smooth Muscle ◽  
Vascular Smooth Muscle ◽  
Smooth Muscle Cells ◽  
Vascular Smooth Muscle Cells ◽  
Muscle Cells ◽  
Mechanical Stretch ◽  
Cyclic Stretch ◽  
Underlying Mechanisms

Background/Aims: Physiological mechanical stretch in vivo helps to maintain the quiescent contractile differentiation of vascular smooth muscle cells (VSMCs), but the underlying mechanisms are still unclear. Here, we investigated the effects of SIRT1 in VSMC differentiation in response to mechanical cyclic stretch. Methods and Results: Rat VSMCs were subjected to 10%-1.25Hz-cyclic stretch in vitro using a FX-4000T system. The data indicated that the expression of contractile markers, including α-actin, calponin and SM22α, was significantly enhanced in VSMCs that were subjected to cyclic stretch compared to the static controls. The expression of SIRT1 and FOXO3a was increased by the stretch, but the expression of FOXO4 was decreased. Decreasing SIRT1 by siRNA transfection attenuated the stretch-induced expression of contractile VSMC markers and FOXO3a. Furthermore, increasing SIRT1 by either treatment with activator resveratrol or transfection with a plasmid to induce overexpression increased the expression of FOXO3a and contractile markers, and decreased the expression of FOXO4 in VSMCs. Similar trends were observed in VSMCs of SIRT1 (+/-) knockout mice. The overexpression of FOXO3a promoted the expression of contractile markers in VSMCs, while the overexpression of FOXO4 demonstrated the opposite effect. Conclusion: Our results indicated that physiological cyclic stretch promotes the contractile differentiation of VSMCs via the SIRT1/FOXO pathways and thus contributes to maintaining vascular homeostasis.

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