Vascular β-adrenoceptor function in hypertension and in ageing

2000 ◽  
Vol 78 (6) ◽  
pp. 433-452 ◽  
Author(s):  
Eva S Werstiuk ◽  
Robert MKW Lee
Keyword(s):  
Smooth Muscle ◽  
Protein Kinase ◽  
Blood Vessels ◽  
Cellular Proliferation ◽  
Second Messengers ◽  
Cell Mass ◽  
Guanine Nucleotide Binding Protein ◽  
Receptor System ◽  
Functional Changes

Functional β-adrenoceptors (β-AR) have been identified and characterized in blood vessels under in vivo conditions as well as in vascular smooth muscle cells (SMC) grown in culture. Agonist occupancy of β-AR activates adenylyl cyclase (AC) via the stimulatory guanine nucleotide-binding protein (Gs) and leads to elevations in intracellular adenosine 3',5'-cyclic monophosphate levels (cAMP). Increased cAMP activates the cAMP-dependent protein kinase (PKA), with subsequent phosphorylation of various target proteins. This β-AR pathway interacts with several other intracellular signalling pathways via cross-talk, so that activation by β-AR agonists may also modulate other second messengers and protein kinases. SMC β-AR play an important role in SMC function. In intact blood vessels they mediate SMC relaxation by various intracellular mechanisms, ultimately causing a decrease in intracellular Ca2+ levels. In cultured SMC, activation of the β-AR pathway results in inhibition of cellular proliferation, the development of SMC polyploidy, and SMC apoptosis. Blood vessels from hypertensive animals are characterized by an increase in SMC cell mass, a greater incidence of SMC polyploidy in the aorta, and an impairment in the β-agonist-mediated SMC relaxation. Some of these changes may result from an attenuation of β-AR function due to agonist-induced receptor desensitization caused by the uncoupling of receptors from the Gs-AC system. The phosphorylated β-AR may in turn trigger new signals and activate different intracellular pathways. However, the details of these mechanisms are still unresolved. Since functional β-AR play such a prominent and multi-faceted role in SMC function, it is important to understand how these diverse physiological effects are mediated by this receptor system, and how they contribute to the development of hypertension. With ageing, a decrease in β-AR-Gs-AC coupling is observed, and this is implicated in the reduced responsiveness of SMC. The similarities in SMC β-AR functional changes in hypertension and in ageing suggest that the underlying mechanisms are also analogous.Key words: smooth muscle, β-adrenoceptors, cyclic AMP, protein kinase A, cell proliferation, polyploidy, relaxation, apoptosis, hypertension, ageing.

scholarly journals Retinoic acid upregulates β1-integrin in vascular smooth muscle cells and alters adhesion to fibronectin

2000 ◽  
Vol 279 (1) ◽  
pp. H382-H387 ◽  
Author(s):  
Meetha M. Medhora
Keyword(s):  
Smooth Muscle ◽  
Retinoic Acid ◽  
Vascular Smooth Muscle ◽  
Blood Vessels ◽  
Physiological Role ◽  
Cellular Growth ◽  
Integrin Subunit ◽  
Adult Rats ◽  
Functional Changes

Retinoic acid has an established physiological role in differentiation, development, and cellular growth. This study investigated the action of all- trans retinoic acid (ATRA) on vascular integrins, cell-surface receptors that control growth and remodeling of blood vessels. The β1-integrin subunit mRNA and protein was induced after treatment with ATRA in two different rat vascular smooth muscle cell lines. To relate this result to the in vivo state, the aortas from adult rats fed with therapeutic doses of ATRA were examined for β1-integrin protein. A significant upregulation of the integrin subunit was observed in vivo. To assess if this increase contributed to physiological changes in cellular function, cells treated with ATRA were tested for alterations in adhesion to extracellular matrix proteins. The cells exposed to the retinoid were seen to adhere more strongly to fibronectin, via the β1-integrin. These results showed that modulation of vascular integrins by ATRA in adult rats contributes to functional changes that can cause remodeling of blood vessels.

scholarly journals Transcranial Imaging of Functional Cerebral Hemodynamic Changes in Single Blood Vessels using in vivo Photoacoustic Microscopy

2012 ◽  
Vol 32 (6) ◽  
pp. 938-951 ◽  
Author(s):  
Lun-De Liao ◽  
Chin-Teng Lin ◽  
Yen-Yu I Shih ◽  
Timothy Q Duong ◽  
Hsin-Yi Lai ◽  
...  
Keyword(s):  
Blood Vessels ◽  
Cerebral Blood Volume ◽  
Hemoglobin Concentration ◽  
Photoacoustic Microscopy ◽  
Functional Changes ◽  
Sagittal Sinus ◽  
Microscopy Technique ◽  
Initial Dip ◽  
Transcranial Imaging

Optical imaging of changes in total hemoglobin concentration ( HbT), cerebral blood volume ( CBV), and hemoglobin oxygen saturation ( SO 2) provides a means to investigate brain hemodynamic regulation. However, high-resolution transcranial imaging remains challenging. In this study, we applied a novel functional photoacoustic microscopy technique to probe the responses of single cortical vessels to left forepaw electrical stimulation in mice with intact skulls. Functional changes in HbT, CBV, and SO 2 in the superior sagittal sinus and different-sized arterioles from the anterior cerebral artery system were bilaterally imaged with unambiguous 36 × 65- μm2 spatial resolution. In addition, an early decrease of SO 2 in single blood vessels during activation (i.e., ‘the initial dip’) was observed. Our results indicate that the initial dip occurred specifically in small arterioles of activated regions but not in large veins. This technique complements other existing imaging approaches for the investigation of the hemodynamic responses in single cerebral blood vessels.

G-protein-coupled-receptor activation of the smooth muscle calponin gene

2001 ◽  
Vol 357 (2) ◽  
pp. 587-592 ◽  
Author(s):  
Nickolai O. DULIN ◽  
Sergei N. ORLOV ◽  
Chad M. KITCHEN ◽  
Tatyana A. VOYNO-YASENETSKAYA ◽  
Joseph M. MIANO
Keyword(s):  
Smooth Muscle ◽  
Protein Kinase ◽  
G Protein ◽  
Transcriptional Activation ◽  
Fold Increase ◽  
Receptor Activation ◽  
G Protein Coupled Receptors ◽  
Mitogen Activated Protein Kinase ◽  
G Protein Coupled

A hallmark of cultured smooth muscle cells (SMCs) is the rapid down-regulation of several lineage-restricted genes that define their in vivo differentiated phenotype. Identifying factors that maintain an SMC differentiated phenotype has important implications in understanding the molecular underpinnings governing SMC differentiation and their subversion to an altered phenotype in various disease settings. Here, we show that several G-protein coupled receptors [α-thrombin, lysophosphatidic acid and angiotensin II (AII)] increase the expression of smooth muscle calponin (SM-Calp) in rat and human SMC. The increase in SM-Calp protein appears to be selective for G-protein-coupled receptors as epidermal growth factor was without effect. Studies using AII showed a 30-fold increase in SM-Calp protein, which was dose- and time-dependent and mediated by the angiotensin receptor-1 (AT1 receptor). The increase in SM-Calp protein with AII was attributable to transcriptional activation of SM-Calp based on increases in steady-state SM-Calp mRNA, increases in SM-Calp promoter activity and complete abrogation of protein induction with actinomycin D. To examine the potential role of extracellular signal-regulated kinase (Erk1/2), protein kinase B, p38 mitogen-activated protein kinase and protein kinase C in AII-induced SM-Calp, inhibitors to each of the signalling pathways were used. None of these signalling molecules appears to be crucial for AII-induced SM-Calp expression, although Erk1/2 may be partially involved. These results identify SM-Calp as a target of AII-mediated signalling, and suggest that the SMC response to AII may incorporate a novel activity of SM-Calp.

scholarly journals Nuclear diacylglycerol is increased during cell proliferation in vivo

1993 ◽  
Vol 290 (3) ◽  
pp. 633-636 ◽  
Author(s):  
H Banfić ◽  
M Žižak ◽  
N Divecha ◽  
R F Irvine
Keyword(s):  
Cell Proliferation ◽  
Protein Kinase C ◽  
Protein Kinase ◽  
Nuclear Membrane ◽  
Cellular Proliferation ◽  
Detectable Change ◽  
Renal Growth ◽  
Kinase C ◽  
Stimulation Of

Highly purified nuclei were prepared from livers and kidneys of rats undergoing compensatory hepatic or renal growth, the former being predominantly by cellular proliferation, and the latter mostly by cellular enlargement. In liver, an increase in nuclear diacylglycerol (DAG) concentration occurred between 16 and 30 h, peaking at around 20 h. At the peak of nuclear DAG production a specific translocation of protein kinase C to the nucleus could be detected; no such changes occurred in kidney. There was no detectable change in whole-cell DAG levels in liver, and the increase in DAG was only measurable in nuclei freed of their nuclear membrane. Overall, these results suggest that there is a stimulation of intranuclear DAG production, possibly through the activation of an inositide cycle [Divecha, Banfić and Irvine (1991) EMBO J. 10, 3207-3214] during cell proliferation in vivo.

scholarly journals Domain Swapping Used To Investigate the Mechanism of Protein Kinase B Regulation by 3-Phosphoinositide-Dependent Protein Kinase 1 and Ser473 Kinase

1999 ◽  
Vol 19 (7) ◽  
pp. 5061-5072 ◽  
Author(s):  
Mirjana Andjelković ◽  
Sauveur-Michel Maira ◽  
Peter Cron ◽  
Peter J. Parker ◽  
Brian A. Hemmings
Keyword(s):  
Protein Kinase ◽  
Kinase Inhibitors ◽  
Protein Kinase B ◽  
Second Messengers ◽  
Activation Mechanism ◽  
Dependent Protein Kinase ◽  
Dependent Protein ◽  
Phosphoinositide 3 Kinase ◽  
Regulatory Sites

ABSTRACT Protein kinase B (PKB or Akt), a downstream effector of phosphoinositide 3-kinase (PI 3-kinase), has been implicated in insulin signaling and cell survival. PKB is regulated by phosphorylation on Thr308 by 3-phosphoinositide-dependent protein kinase 1 (PDK1) and on Ser473 by an unidentified kinase. We have used chimeric molecules of PKB to define different steps in the activation mechanism. A chimera which allows inducible membrane translocation by lipid second messengers that activate in vivo protein kinase C and not PKB was created. Following membrane attachment, the PKB fusion protein was rapidly activated and phosphorylated at the two key regulatory sites, Ser473 and Thr308, in the absence of further cell stimulation. This finding indicated that both PDK1 and the Ser473 kinase may be localized at the membrane of unstimulated cells, which was confirmed for PDK1 by immunofluorescence studies. Significantly, PI 3-kinase inhibitors prevent the phosphorylation of both regulatory sites of the membrane-targeted PKB chimera. Furthermore, we show that PKB activated at the membrane was rapidly dephosphorylated following inhibition of PI 3-kinase, with Ser473 being a better substrate for protein phosphatase. Overall, the results demonstrate that PKB is stringently regulated by signaling pathways that control both phosphorylation/activation and dephosphorylation/inactivation of this pivotal protein kinase.

scholarly journals Membrane-Bound Protein Kinase A Inhibits Smooth Muscle Cell Proliferation In Vitro and In Vivo by Amplifying cAMP–Protein Kinase A Signals

2001 ◽  
Vol 88 (3) ◽  
pp. 319-324 ◽  
Author(s):  
Ciro Indolfi ◽  
Eugenio Stabile ◽  
Carmela Coppola ◽  
Adriana Gallo ◽  
Cinzia Perrino ◽  
...  
Keyword(s):  
Cell Proliferation ◽  
Smooth Muscle ◽  
Protein Kinase ◽  
Smooth Muscle Cell ◽  
Protein Kinase A ◽  
Membrane Bound ◽  
Proliferation In Vitro ◽  
Kinase A

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.

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