Remodeling of resistance arteries in organoid culture is modulated by pressure and pressure pulsation and depends on vasomotion

2004 ◽  
Vol 286 (6) ◽  
pp. H2052-H2056 ◽  
Author(s):  
Erik N. T. P. Bakker ◽  
Oana Sorop ◽  
Jos A. E. Spaan ◽  
Ed VanBavel
Keyword(s):  
High Pressure ◽  
Vascular Remodeling ◽  
Pressure Pulsation ◽  
Progressive Increase ◽  
Pressure Level ◽  
Lumen Diameter ◽  
Myogenic Tone ◽  
Cremaster Muscle ◽  
Resistance Arteries ◽  
Organoid Culture

The hypothesis was tested that pressure and pressure pulsation modulate vascular remodeling. Arterioles (∼200 μm lumen diameter) were dissected from rat cremaster muscle and studied in organoid culture. In the first series, arterioles were kept at a stable pressure level of either 50 or 100 mmHg for 3 days. Both groups showed a progressive increase in myogenic tone during the experiment. Arterioles kept at 50 mmHg showed larger endothelium-dependent dilation, compared with vessels kept at 100 mmHg on day 3. Remodeling, as indicated by the reduction in maximally dilated diameter at 100 mmHg, was larger in arterioles kept at 50 mmHg compared with 100 mmHg: 34 ± 4.5 versus 10 ± 4.8 μm ( P < 0.05). In the second series, arterioles were subjected to a stable pressure of 60 mmHg or oscillating pressure of 60 ± 10 mmHg (1.5 Hz) for 4 days. Pressure pulsation induced partial dilation and was associated with less remodeling: 34 ± 4.0 versus 19 ± 4.5 μm ( P < 0.01) for stable pressure versus oscillating pressure. Vasomotion was frequently observed in all groups, and inward remodeling was larger in vessels with vasomotion: 30 ± 2.5 μm compared with vessels that did not exhibit vasomotion: 8.0 ± 5.0 μm ( P < 0.01). In conclusion, these results indicate that remodeling is not enhanced by high pressure. Pressure pulsation causes partial dilation and reduces inward remodeling. The appearance of vasomotion is associated with enhanced inward remodeling.

Role of T-type calcium channels in myogenic tone of skeletal muscle resistance arteries

2002 ◽  
Vol 283 (6) ◽  
pp. H2239-H2243 ◽  
Author(s):  
Ed VanBavel ◽  
Oana Sorop ◽  
Ditte Andreasen ◽  
Martin Pfaffendorf ◽  
Boye L. Jensen
Keyword(s):  
Calcium Channels ◽  
Southern Blotting ◽  
Myogenic Tone ◽  
Cremaster Muscle ◽  
Resistance Arteries ◽  
Rt Pcr ◽  
Response Curves ◽  
Potent Effect ◽  
Channel Expression

T-type calcium channels may be involved in the maintenance of myogenic tone. We tested their role in isolated rat cremaster arterioles obtained after CO2anesthesia and decapitation. Total RNA was analyzed by RT-PCR and Southern blotting for calcium channel expression. We observed expression of voltage-operated calcium (CaV) channels CaV3.1 (T-type), CaV3.2 (T-type), and CaV1.2 (L-type) in cremaster arterioles ( n= 3 rats). Amplification products were observed only in the presence of reverse transcriptase and cDNA. Concentration-response curves of the relatively specific L-type blocker verapamil and the relatively specific T-type blockers mibefradil and nickel were made on cannulated vessels with either myogenic tone (75 mmHg) or a similar level of constriction induced by 30 mM K+ at 35 mmHg. Mibefradil and nickel were, respectively, 162-fold and 300-fold more potent in inhibiting myogenic tone compared with K+-induced constriction [log(IC50, M): mibefradil, basal −7.3 ± 0.2 ( n = 9) and K+ −5.1 ± 0.1 ( n = 5); nickel, basal −4.1 ± 0.2 ( n = 5) and K+ −1.6 ± 0.5 ( n = 5); means ± SE]. Verapamil had a 17-fold more potent effect [log(IC50, M): basal −6.6 ± 0.1 ( n = 5); K+ −5.4 ± 0.3 ( n = 4); all log(IC50) P < 0.05, basal vs. K+]. These data suggest that T-type calcium channels are expressed and involved in maintenance of myogenic tone in rat cremaster muscle arterioles.

Flow inhibits inward remodeling in cannulated porcine small coronary arteries

2005 ◽  
Vol 289 (6) ◽  
pp. H2632-H2640 ◽  
Author(s):  
Adrian Pistea ◽  
Erik N. T. P. Bakker ◽  
Jos A. E. Spaan ◽  
Ed VanBavel
Keyword(s):  
Coronary Arteries ◽  
Vascular Remodeling ◽  
Culture Period ◽  
Control Group ◽  
Shear Stresses ◽  
No Production ◽  
Flow Conditions ◽  
Resistance Arteries ◽  
Organoid Culture ◽  
Flow Through

The mechanisms of flow-induced vascular remodeling are poorly understood, especially in the coronary microcirculation. We hypothesized that application of flow in small coronary arteries in organoid culture would cause a nitric oxide (NO)-mediated dilation and inhibit inward remodeling. We developed an organoid culture setup to drive a flow through cannulated arterioles at constant luminal pressure via a pressure gradient between the pipettes. Subepicardial porcine coronary arterioles with diameter at full dilation and 60 mmHg ( D0) of 168 ± 10 (SE) μm were cannulated. Vessels treated with Nω-nitro-l-arginine (l-NNA) to block NO production and untreated vessels were pressurized at 60 mmHg for 3 days with and without flow. Endothelium-dependent dilation to 10−7 M bradykinin was preserved in all groups. Tone was significantly less in vessels cultured under flow conditions in the last half of the culture period. Untreated and l-NNA-treated vessels regulated their diameter to yield shear stresses of 10.3 ± 2.1 and 14.0 ± 2.4 (SE) dyn/cm2, respectively (not significantly different). Without l-NNA, passive pressure-diameter curves at the end of the culture period revealed inward remodeling in the control group [to 92.3 ± 1.3% of D0 (SE)] and no remodeling in the vessels cultured under flow conditions (100.2 ± 1.3% of D0); with l-NNA, the group subjected to flow showed inward remodeling (92.1 ± 2.5% of D0). We conclude that pressurized coronary resistance arteries could be maintained in culture for several days with flow. Vessels cultured under flow conditions remained more dilated when NO synthesis was blocked. Inward remodeling occurred in vessels cultured under no-flow conditions and was inhibited by flow-dependent NO synthesis.

Enhanced resistance artery sensitivity to agonists under isobaric compared with isometric conditions

1994 ◽  
Vol 266 (1) ◽  
pp. H147-H155 ◽  
Author(s):  
W. R. Dunn ◽  
G. C. Wellman ◽  
J. A. Bevan
Keyword(s):  
Membrane Potential ◽  
Angiotensin Ii ◽  
Myogenic Tone ◽  
Isometric Contractions ◽  
Fundamental Interaction ◽  
Resistance Artery ◽  
Resistance Arteries ◽  
Enhanced Resistance ◽  
Increased Sensitivity

We have compared the responsiveness of rabbit mesenteric resistance arteries with agonists under isometric and isobaric conditions. When pressurized (60 mmHg), arteries spontaneously reduced their diameter by 18.1%. An equivalent isometric stress did not generate force in a “wire” myograph. Subsequently, much higher concentrations of norepinephrine (NE) and histamine were required to cause isometric contractions than were needed to reduce vascular diameter of pressurized vessels, whereas angiotensin II produced a maintained response only in pressurized arteries. Reducing transmural pressure to 20 mmHg abolished pressure-induced myogenic tone and decreased arterial sensitivity to NE. Under isometric conditions, partial depolarization with KCl increased sensitivity to NE and histamine to within the concentration range effective in pressurized vessels and also "revealed" responses to angiotensin II. The membrane potential of the vascular smooth muscle cells under partially depolarized conditions was similar to that found in vivo and in vessels studied isobarically. These observations demonstrate a fundamental interaction between pressure-induced myogenic tone and the sensitivity of resistance arteries to vasoactive stimuli. This influence was mimicked in isometrically mounted vessels by partial depolarization, indicating a possible pivotal role for membrane potential in determining the reactivity of the resistance vasculature.

Abstract 485: Novel Mechanisms at Immune-vascular Interfaces Regulates Myogenic Tone of Resistance Arteries and Induce Hypertension in Mice

2018 ◽  
Vol 38 (Suppl_1) ◽  
Author(s):  
Daniela Carnevale ◽  
Iolanda Vinciguerra ◽  
Manuel Casaburo ◽  
Marialuisa Perrotta ◽  
Roberta Iacobucci ◽  
...  
Keyword(s):  
Myogenic Tone ◽  
Resistance Arteries

Pulsation-induced dilation of subendocardial and subepicardial arterioles: effect on vasodilator sensitivity

2002 ◽  
Vol 282 (1) ◽  
pp. H311-H319 ◽  
Author(s):  
Oana Sorop ◽  
Jos A. E. Spaan ◽  
Ed VanBavel
Keyword(s):  
Blood Flow ◽  
Intracellular Calcium ◽  
Pressure Pulsation ◽  
Coronary Vessels ◽  
Resistance Arteries ◽  
Fura 2 ◽  
Compression Effect ◽  
Steady Pressure

Coronary vessels are squeezed by the surrounding myocardium during systole, impeding blood flow specifically in the subendocardium. To study the myocardial compression effect, we applied pulsatile transvascular pressure to isolated, cannulated subendocardial (Endo) and subepicardial (Epi) resistance arteries. Pressure pulsation at 0.5 to 2.5 Hz between 20 and 100 mmHg induced dilation of preconstricted vessels that was somewhat larger in Epi arterioles. In four Epi and five Endo arterioles loaded with fura 2, pulsation led to a small increase in intracellular calcium. Pulsation induced a significant decrease in IC50for bradykinin (BK) (5.9 ± 0.6 vs. 27.3 ± 3.2 nM in Epi vessels and 7.6 ± 0.3 vs. 302 ± 9 nM in Endo vessels), compared with steady pressure. The adenosine (Ado) sensitivity was not significantly affected (2.21 ± 0.08 vs. 3.76 ± 0.4 μM) in Epi arteries but was enhanced during pulsations in Endo vessels (3.1 ± 0.3 vs. 10.1 ± 0.6 μM). When pulsation-induced dilation was compensated by a higher concentration of the preconstrictor (U-46619), a significantly larger dilation to BK or Ado was found during pulsations. In conclusion, pulsation-induced dilation occurs at physiologically relevant frequencies and amplitudes in Endo vessels. The process does not involve intracellular calcium reduction and increases vasodilator sensitivity.

Microbiological Changes in Pressurized, Prepackaged Sliced Cooked Ham

1999 ◽  
Vol 62 (12) ◽  
pp. 1411-1415 ◽  
Author(s):  
M. E. LÓPEZ-CABALLERO ◽  
J. CARBALLO ◽  
F. JIMÉNEZ-COLMENERO
Keyword(s):  
High Pressure ◽  
Processing Time ◽  
Microbiological Quality ◽  
Viable Count ◽  
Pressure Level ◽  
Binding Properties ◽  
Water Binding ◽  
Chilled Storage ◽  
Cooked Ham ◽  
Brochothrix Thermosphacta

This was a study of the influence of high-pressure conditions (200 and 400 MPa, 5 and 20 min, 7°C) on microbiological quality and water-binding properties of vacuum-prepackaged sliced cooked ham and how this affects microbiological changes during chilled storage (2°C). Pressurization caused a degree of microbiological inactivation, which increased with pressure level and processing time. Pressurization at 400 MPa significantly reduced the total viable count and lactic acid bacteria to the extent that after 20 min no Enterobacteriaceae, Baird Parker flora, or Brochothrix thermosphacta were detected throughout any of the chilled storage periods studied. In general, gram-positive flora was more resistant to pressure than gram-negative flora. The fact that high pressure (400 MPa) causes considerable inactivation of microorganisms could be used to prolong the shelf life of vacuum-prepackaged sliced cooked ham.

Design, Part Load and Transient Operation of Combined Cycle Plants With Water Flashing

1995 ◽  
Author(s):  
P. J. Dechamps
Keyword(s):  
High Pressure ◽  
Steam Generator ◽  
Gas Turbines ◽  
Heat Recovery ◽  
Vapour Phase ◽  
Pressure Level ◽  
Combined Cycle ◽  
Saturated Steam ◽  
Heat Recovery Steam Generator ◽  
Combined Cycles

The last decade has seen remarkable improvement in gas turbine based power generation technologies, with the increasing use of natural gas-fuelled combined cycle units in various regions of the world. The struggle for efficiency has produced highly complex combined cycle schemes based on heat recovery steam generators with multiple pressure levels and possibly reheat. As ever, the evolution of these schemes is the result of a technico-economic balance between the improvement in performance and the increased costs resulting from a more complex system. This paper looks from the thermodynamic point of view at some simplified combined cycle schemes based on the concept of water flashing. In such systems, high pressure saturated water is taken off the high pressure drum and flashed into a tank. The vapour phase is expanded as low pressure saturated steam or returned to the heat recovery steam generator for superheating, whilst the liquid phase is recirculated through the economizer. With only one drum and three or four heat exchangers in the boiler as in single pressure level systems, the plant might have a performance similar to that of a more complex dual pressure level system. Various configurations with flash tanks are studied based on commercially available 150 MW-class E-technology gas turbines and compared with classical multiple pressure level combined cycles. Reheat units are covered, both with flash tanks and as genuine combined cycles for comparison purposes. The design implications for the heat recovery steam generator in terms of heat transfer surfaces are emphasized. Off-design considerations are also covered for the flash based schemes, as well as transient performances of these schemes, because the simplicity of the flash systems compared to normal combined cycles significantly affects the dynamic behaviour of the plant.

Sign in / Sign up

Export Citation Format

Share Document