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.

A review of changes in vascular smooth muscle functions in hypertension: isolated tissue versus in vivo studies

1985 ◽  
Vol 63 (4) ◽  
pp. 355-365 ◽  
Author(s):  
C. R. Triggle ◽  
I. Laher
Keyword(s):  
Smooth Muscle ◽  
Vascular Smooth Muscle ◽  
Muscle Function ◽  
Spontaneously Hypertensive Rat ◽  
In Vivo Studies ◽  
Neuronal Uptake ◽  
Smooth Muscle Function

The role of altered vascular smooth muscle function in the etiology of essential hypertension has been extensively studied by a number of investigators. The results obtained from in vivo studies do not always correlate with results from in vitro studies and it is not always apparent whether the results reflect differences related to hypertension or to the genetic background of the animal model. In vitro and perfused vascular bed studies in our laboratory have utilized the spontaneously hypertensive rat (SHR), the normotensive Wistar Kyoto rat (WKY), genetically related crossbred rats (F1, F2, and BC1), and also Dahl salt-sensitive (DS) and salt-resistant (DR) rats. The role of altered smooth muscle function in relation to the development of the elevated blood pressure (BP) of the SHR or DS rat was studied and emphasis was placed on determining the role of altered neuronal uptake1 (U1) in hypertensives in masking elevated postsynaptic sensitivity to noradrenaline. In addition, the relationship between postsynaptic sensitivity to cations and BP was assessed. Such studies have indicated that alterations in postsynaptic sensitivity, U1 activity, and sensitivity to cations are not entirely consistent with the etiology of hypertension in the SHR and DS rat but may simply reflect genetic strain differences between the hypertensive and normotensive animals.

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.

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 Aging-associated changes in microRNA expression profile of internal anal sphincter smooth muscle: Role of microRNA-133a

2016 ◽  
Vol 311 (5) ◽  
pp. G964-G973 ◽  
Author(s):  
Jagmohan Singh ◽  
Ettickan Boopathi ◽  
Sankar Addya ◽  
Benjamin Phillips ◽  
Isidore Rigoutsos ◽  
...  
Keyword(s):  
Smooth Muscle ◽  
Anal Sphincter ◽  
Internal Anal Sphincter ◽  
Smooth Muscles ◽  
Smooth Muscle Contractility ◽  
Network Analyses ◽  
Rhoa Signaling

A comprehensive genomic and proteomic, computational, and physiological approach was employed to examine the (previously unexplored) role of microRNAs (miRNAs) as regulators of internal anal sphincter (IAS) smooth muscle contractile phenotype and basal tone. miRNA profiling, genome-wide expression, validation, and network analyses were employed to assess changes in mRNA and miRNA expression in IAS smooth muscles from young vs. aging rats. Multiple miRNAs, including rno-miR-1, rno-miR-340-5p, rno-miR-185, rno-miR-199a-3p, rno-miR-200c, rno-miR-200b, rno-miR-31, rno-miR-133a, and rno-miR-206, were found to be upregulated in aging IAS. qPCR confirmed the upregulated expression of these miRNAs and downregulation of multiple, predicted targets ( Eln, Col3a1, Col1a1, Zeb2, Myocd, Srf, Smad1, Smad2, Rhoa/Rock2, Fn1, Tagln v2, Klf4, and Acta2) involved in regulation of smooth muscle contractility. Subsequent studies demonstrated an aging-associated increase in the expression of miR-133a, corresponding decreases in RhoA, ROCK2, MYOCD, SRF, and SM22α protein expression, RhoA-signaling, and a decrease in basal and agonist [U-46619 (thromboxane A2analog)]-induced increase in the IAS tone. Moreover, in vitro transfection of miR-133a caused a dose-dependent increase of IAS tone in strips, which was reversed by anti-miR-133a. Last, in vivo perianal injection of anti-miR-133a reversed the loss of IAS tone associated with age. This work establishes the important regulatory effect of miRNA-133a on basal and agonist-stimulated IAS tone. Moreover, reversal of age-associated loss of tone via anti-miR delivery strongly implicates miR dysregulation as a causal factor in the aging-associated decrease in IAS tone and suggests that miR-133a is a feasible therapeutic target in aging-associated rectoanal incontinence.

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.

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