scholarly journals Electrical propagation of vasodilatory signals in capillary networks

2019 ◽  
Author(s):  
Pilhwa Lee
Keyword(s):  
Blood Flow ◽  
Oxygen Tension ◽  
Atp Release ◽  
Blood Perfusion ◽  
Signal Propagation ◽  
Electrical Signal ◽  
Membrane Area ◽  
Capillary Networks ◽  
Physiological Relevance ◽  
Electrical Propagation

AbstractA computational model is developed to study electrical propagation of vasodilatory signals and arteriolar regulation of blood flow depending on the oxygen tension and agonist distribution in capillary network. The involving key parameters of endothelial cell-to-cell electrical conductivity and plasma membrane area per unit volume were calibrated with the experimental data on an isolated endothelial tube of mouse skeletal feeding arteries. The oxygen saturation parameters in terms of ATP release from erythrocytes are estimated from the data of a left anterior descending coronary blood perfusion of dog. In regard to the acetylcholine induced upstream conduction, our model shows that spatially uniform superfusion of acetylcholine attenuates the electrical signal propagation, and blocking calcium activated potassium channels suppresses that attenuation. On the other hand, local infusion of acetylcholine induces enhanced electrical propagation that corresponds to physiological relevance. In the integration of the endothelial tube and the lumped arterioles vessel model, we show that endothelial purinergic oxygen sensing of ATP released from erythrocytes and local infusion of acetylcholine are all individually effective to induce vasodilatory signals to regulate blood flow in arterioles. We have recapitulated the upstream vasomotion in arterioles from the elevated oxygen tension in the downstream capillary domain. This study is a foundation for characterizing effective pharmaceutical strategies for ascending vasodilation and oxygenation.

Oxygen tension distribution in postcapillary venules in resting skeletal muscle

2003 ◽  
Vol 285 (5) ◽  
pp. H1980-H1985 ◽  
Author(s):  
Darin J. Saltzman ◽  
Andras Toth ◽  
Amy G. Tsai ◽  
Marcos Intaglietta ◽  
Paul C. Johnson
Keyword(s):  
Skeletal Muscle ◽  
Blood Flow ◽  
Standard Deviation ◽  
Oxygen Tension ◽  
Control Mechanisms ◽  
Mean Flow ◽  
Tension Distribution ◽  
Capillary Networks ◽  
Single Animal ◽  
The Mean

We tested the hypothesis that blood flow is distributed among capillary networks in resting skeletal muscle in such a manner as to maintain uniform end-capillary Po2. Oxygen tension in venules draining two to five capillaries was obtained by using the phosphorescence decay methodology in rat spinotrapezius muscle. For 64 postcapillary venules among 18 networks in 10 animals, the mean Po2 was 30.1 Torr (range, 9.7–43.5 Torr) with a coefficient of variation (CV; standard deviation/mean) of 0.26. Oxygen levels of postcapillary venules within a single network or single animal, however, displayed a much smaller CV (0.064 and 0.094, respectively). By comparison, the CV of blood flow in 57 postcapillary venules of 17 networks in 9 animals was 1.27 with a mean flow of 0.011 ± 0.014 nl/s and a range of 3.7 × 10–4 to 6.5 × 10–2 nl/s. Blood flow of postcapillary venules within single networks displayed a lower CV (mean, 0.51), whereas that in individual animals was 0.78. Results indicate that among venular networks, heterogeneity of oxygen tension is less than that of blood flow and within venular networks the heterogeneity of oxygen tension is much less than that of blood flow. In addition, postcapillary Po2 was independent of flow among venules in which both were measured. Results of this study may be attributable to three factors: 1) O2 diffusion between adjacent capillaries and venules, 2) structural remodeling in regions of lower Po2, and 3) O2-dependent local control mechanisms.

scholarly journals Oxygen Tension and Blood Flow in Relation to Revascularization in Transplanted Adult and Fetal Rat Pancreatic Islets

2002 ◽  
Vol 11 (8) ◽  
pp. 813-820 ◽  
Author(s):  
Per-Ola Carlsson ◽  
Göran Mattsson
Keyword(s):  
Blood Flow ◽  
Pancreatic Islets ◽  
Oxygen Tension ◽  
Blood Perfusion ◽  
Vascular Density ◽  
Low Oxygen ◽  
Doppler Flowmetry ◽  
Rat Pancreatic Islets ◽  
Low Oxygen Tension ◽  
Fetal Islets

We have previously recorded a decreased oxygen tension and blood flow in syngeneically transplanted rat pancreatic islets. The present study related measurements of oxygen tension and blood flow to the vascular density in such grafts implanted beneath the renal capsule. We also evaluated whether transplanted fetal islets are better revascularized than adult islets, and if the degree of revascularization is directly related to the islet vascular endothelial growth factor (VEGF) production. Tissue pO2 was measured using Clark microelectrodes, whereas islet graft blood flow was measured with laser-Doppler flowmetry. The vascular density of endogenous and transplanted islets was quantified in histological specimens stained with the lectin Bandeiraea simplicifolia (BS-1). Tissue pO2 in the transplanted adult and fetal islet grafts was similar and markedly lower than in the endogenous islets. The blood perfusion of both the adult and fetal islet grafts was 60–65% of that in the renal cortex. Administration of d-glucose did not affect tissue pO2 in either the endogenous or transplanted islets, nor graft blood perfusion. The number of capillaries found in the transplanted adult and fetal islets was similar and markedly lower than in endogenous islets. However, in the connective tissue stroma, which constituted ~20% of all islet grafts, the vascular density was higher than in the corresponding endocrine parts of these grafts. Incubated adult islets released higher amounts of VEGF than fetal islets. In conclusion, the previously described low oxygen tension of syngeneically transplanted adult rat islets is related to a low vascular density. Similar low oxygen tension and vascular density are seen in grafted fetal islets. The amount of VEGF production does not correlate to the degree of revascularization of the grafts.

scholarly journals Diagnosis of Fibrotic Distal Ileum Stenosis after Ischemic Enteritis Using Transabdominal Ultrasonography

2021 ◽  
pp. 568-577
Author(s):  
Ryo Katsumata ◽  
Noriaki Manabe ◽  
Masaki Matsubara ◽  
Jun Nakamura ◽  
Kazuma Kawahito ◽  
...  
Keyword(s):  
Blood Flow ◽  
Case Reports ◽  
Blood Perfusion ◽  
Distal Ileum ◽  
Wall Thickening ◽  
Current Case ◽  
Abdominal Ultrasonography ◽  
Transabdominal Ultrasonography ◽  
Stenotic Lesion ◽  
Ischemic Enteritis

Ischemic enteritis (IE) is a rare disorder which is caused by inadequate blood flow to small intestine. The diagnostic procedure of this disease has not sufficiently established because of its rarity. Here, we report a case of IE in a hemodialysis-dependent 70-year-old man and summarize the diagnostic options for IE. The patient was admitted to our hospital because of acute abdominal distention and vomiting. He presented with mild tenderness in the lower abdomen and slightly elevated C-reactive protein level as revealed by blood tests. Radiographic imaging showed small bowel obstruction due to a stricture in the distal ileum. Contrast-enhanced abdominal ultrasonography revealed a 7-cm stenotic site with increased intestinal wall thickening, which preserved mucosal blood perfusion. Elastography revealed a highly elastic alteration of the stenotic lesion, indicating benign fibrotic changes resulting from chronic insufficient blood flow. Based on a clinical diagnosis of IE with fibrous stenosis, a partial ileostomy was performed. After surgical treatment, oral intake was initiated without recurrence of intestinal obstruction. Pathological findings revealed deep ulceration with inflammatory cell infiltration at the stenotic site. Occlusion and hyalinization of the venules in the submucosal layer indicated IE. In addition to current case, we reviewed past case reports of IE. Through this case presentation and literature review, we summarize the usefulness and safety of transabdominal ultrasonography for diagnosing IE.

Local blood flow, oxygen tension, and oxygen consumption in the rat spinal cord

1983 ◽  
Vol 58 (4) ◽  
pp. 526-530 ◽  
Author(s):  
Nariyuki Hayashi ◽  
Barth A. Green ◽  
Mayra Gonzalez-Carvajal ◽  
Joseph Mora ◽  
Richard P. Veraa
Keyword(s):  
Spinal Cord ◽  
Blood Flow ◽  
Oxygen Consumption ◽  
Oxygen Tension ◽  
Tissue Oxygen ◽  
Local Blood Flow ◽  
Rat Spinal Cord ◽  
Spinal Cord Blood Flow ◽  
Content Type ◽  
Tissue Oxygen Consumption

✓ Using a reliable and reproducible microelectrode technique, consistent simultaneous measurements of local spinal cord blood flow (SCBF), tissue oxygen tension, and tissue oxygen consumption were made at cervical, thoracic, and lumbar levels in the rat spinal cord. These observations showed that the metabolic state is maintained constant along the cord, despite significant variations in vasculature. The physiological and anatomical aspects of these findings are discussed.

EFFECT OF CARBON DIOXIDE (HYPOCAPNIA AND HYPERCAPNIA) ON INTERNAL MAMMARY-CORONARY ARTERIAL BYPASS GRAFT BLOOD FLOW AND REGIONAL MYOCARDIAL OXYGEN TENSION IN THE DOG

1994 ◽  
Vol 81 (SUPPLEMENT) ◽  
pp. A718
Author(s):  
K. Okazaki ◽  
H. Nose ◽  
Y. Okutsu ◽  
F. Okumura ◽  
A. F. Fukunaga
Keyword(s):  
Carbon Dioxide ◽  
Blood Flow ◽  
Oxygen Tension ◽  
Bypass Graft ◽  
Arterial Bypass ◽  
Internal Mammary ◽  
Arterial Bypass Graft

Activins, Inhibins, and Follistatins: From Endocrinology to Signaling. A Paradigm for the New Millennium

2002 ◽  
Vol 227 (9) ◽  
pp. 724-752 ◽  
Author(s):  
Corrine Welt ◽  
Yisrael Sidis ◽  
Henry Keutmann ◽  
Alan Schneyer
Keyword(s):  
Hormone Secretion ◽  
Signal Propagation ◽  
Cellular Level ◽  
Model Systems ◽  
Pituitary Hormone ◽  
New Paradigm ◽  
Activin Signaling ◽  
Physiological Relevance ◽  
Paracrine Growth Factor

It has been 70 years since the name inhibin was used to describe a gonadal factor that negatively regulated pituitary hormone secretion. The majority of this period was required to achieve purification and definitive characterization of inhibin, an event closely followed by identification and characterization of activin and follistatin (FS). In contrast, the last 15–20 years saw a virtual explosion of information regarding the biochemistry, physiology, and biosynthesis of these proteins, as well as identification of activin receptors, and a unique mechanism for FS action—the nearly irreversible binding and neutralization of activin. Many of these discoveries have been previously summarized; therefore, this review will cover the period from the mid 1990s to present, with particular emphasis on emerging themes and recent advances. As the field has matured, recent efforts have focused more on human studies, so the endocrinology of inhibin, activin, and FS in the human is summarized first. Another area receiving significant recent attention is local actions of activin and its regulation by both FS and inhibin. Because activin and FS are produced in many tissues, we chose to focus on a few particular examples with the most extensive experimental support, the pituitary and the developing follicle, although nonreproductive actions of activin and FS are also discussed. At the cellular level, it now seems that activin acts largely as an autocrine and/or paracrine growth factor, similar to other members of the transforming growh factor β superfamily. As we discuss in the next section, its actions are regulated extracellularly by both inhibin and FS. In the final section, intracellular mediators and modulators of activin signaling are reviewed in detail. Many of these are shared with other transforming growh factor β superfamily members as well as unrelated molecules, and in a number of cases, their physiological relevance to activin signal propagation remains to be elucidated. Nevertheless, taken together, recent findings suggest that it may be more appropriate to consider a new paradigm for inhibin, activin, and FS in which activin signaling is regulated extracellularly by both inhibin and FS whereas a number of intracellular proteins act to modulate cellular responses to these activin signals. It is therefore the balance between activin and all of its modulators, rather than the actions of any one component, that determines the final biological outcome. As technology and model systems become more sophisticated in the next few years, it should become possible to test this concept directly to more clearly define the role of activin, inhibin, and FS in reproductive physiology.

scholarly journals Neurite, a Finite Difference Large Scale Parallel Program for the Simulation of Electrical Signal Propagation in Neurites under Mechanical Loading

PLoS ONE ◽  
2015 ◽  
Vol 10 (2) ◽  
pp. e0116532 ◽  
Author(s):  
Julián A. García-Grajales ◽  
Gabriel Rucabado ◽  
Antonio García-Dopico ◽  
José-María Peña ◽  
Antoine Jérusalem
Keyword(s):  
Finite Difference ◽  
Mechanical Loading ◽  
Large Scale ◽  
Signal Propagation ◽  
Electrical Signal ◽  
Parallel Program

scholarly journals Blood Perfusion of the Kidney of Lophius Piscatorius L.

1953 ◽  
Vol 32 (2) ◽  
pp. 329-336 ◽  
Author(s):  
L. Brull ◽  
E. Nizet ◽  
E. B. Verney
Keyword(s):  
Blood Flow ◽  
Critical Level ◽  
Perfusion Pressure ◽  
Blood Perfusion ◽  
Urine Flow ◽  
The Other ◽  
Protein Nitrogen ◽  
Other Hand ◽  
Flow Through

Lophius kidneys perfused with the heparinized blood (venous) of the fish secrete urine in which total non-protein nitrogen is concentrated, magnesium highly concentrated, and chloride only slightly so or not at all. Oxygenation of the blood, or lowering the temperature of the perfusate from c. 20° to c. 5° C. does not appear to influence secretion. The blood flow through the kidneys increases with the perfusion pressure, the increase often becoming disproportionately large. The urine flow, on the other hand, above a certain critical level is largely independent of changes in perfusion pressure.

Iodixanol is readily eliminated by hemodialysis

1998 ◽  
Vol 39 (4) ◽  
pp. 372-374 ◽  
Author(s):  
K. J. Berg ◽  
B. Rolfsen ◽  
G. Stake
Keyword(s):  
Blood Flow ◽  
Contrast Medium ◽  
Hollow Fiber ◽  
Cellulose Triacetate ◽  
High Flux ◽  
Hollow Fiber Membranes ◽  
Polysulfone Membrane ◽  
Membrane Area ◽  
X Ray

Purpose, Material and Methods, and Results: The dialyzability of the high-molecular X-ray contrast medium iodixanol was examined in an in vitro hemo-dialysis model using two different hollow fiber membranes: one high-flux (polysulfone) membrane and one intermediate-flux (cellulose triacetate) membrane. Blood flow was 200 ml/min and membrane area 1.3 m2. The dialyzer clearance of iodixanol dissolved in a mixture of leukocyte-filtered SAG-M blood and compatible citrate plasma was 134.2±3.6 ml/min for the polysulfone membrane and 113.0±3.6 ml/min for the cellulose triacetate membrane. Conclusion: Iodixanol is readily dialyzed through commercial high-flux membranes.

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