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Seminars in Nephrology Mar 2015Endothelin (ET) is one of the most potent renal vasoconstrictors. Endothelin plays an essential role in the regulation of renal blood flow, glomerular filtration, sodium... (Review)
Review
Endothelin (ET) is one of the most potent renal vasoconstrictors. Endothelin plays an essential role in the regulation of renal blood flow, glomerular filtration, sodium and water transport, and acid-base balance. ET-1, ET-2, and ET-3 are the three distinct endothelin isoforms comprising the endothelin family. ET-1 is the major physiologically relevant peptide and exerts its biological activity through two G-protein-coupled receptors: ET(A) and ET(B). Both ET(A) and ET(B) are expressed by the renal vasculature. Although ET(A) are expressed mainly by vascular smooth muscle cells, ET(B) are expressed by both renal endothelial and vascular smooth muscle cells. Activation of the endothelin system, or overexpression of downstream endothelin signaling pathways, has been implicated in several pathophysiological conditions including hypertension, acute kidney injury, diabetic nephropathy, and immune nephritis. In this review, we focus on the effects of endothelin on the renal microvasculature, and update recent findings on endothelin in the regulation of renal hemodynamics.
Topics: Endothelins; Glomerular Filtration Rate; Humans; Microcirculation; Renal Circulation
PubMed: 25966346
DOI: 10.1016/j.semnephrol.2015.02.004 -
Angiology Oct 2021
Topics: Coronary Circulation; Humans; Microcirculation
PubMed: 33827275
DOI: 10.1177/00033197211007702 -
Current Opinion in Nephrology and... Nov 2022Patients with chronic kidney disease characteristically exhibit microcirculatory dysfunction, in combination with vascular damage. Hemodialysis superimposes additional... (Review)
Review
PURPOSE OF REVIEW
Patients with chronic kidney disease characteristically exhibit microcirculatory dysfunction, in combination with vascular damage. Hemodialysis superimposes additional circulatory stress to the microvasculature (repetitive ischemic insults/cumulative damage) resulting in high mortality. Intradialytic monitoring and hemodialysis delivery is currently limited to macrovascular/systemic assessment and detection of intradialytic systemic hypotension. Monitoring of the microcirculation has the potential to provide valuable information on hemodialysis-induced circulatory stress likely to result in end-organ ischemia (with/without systemic hypotension) generating an opportunity to intervene before tissue injury occurs.
RECENT FINDINGS
Various noninvasive technologies have been used assessing the microcirculation in hemodialysis patients at rest. Some technologies have also been applied during hemodialysis studying the effects of treatment on the microcirculation. Despite the approach used, results are consistent. Hemodialysis patients have impaired microcirculations with treatment adding additional stress to inadequately regulated vascular beds. Utility/practicality/clinical relevance vary significantly between methodologies.
SUMMARY
Intradialytic monitoring of the microcirculation can provide additional insights into a patient's individual response to treatment. However, this valuable perspective has not been adopted into clinical practice. A microcirculatory view could provide a window of opportunity to enable a precision medicine approach to treatment delivery improving current woefully poor subjective and objective clinical outcomes.
Topics: Humans; Hypotension; Microcirculation; Renal Dialysis; Renal Insufficiency, Chronic
PubMed: 36172854
DOI: 10.1097/MNH.0000000000000831 -
Biomedicine & Pharmacotherapy =... Aug 2023Coronary microvascular dysfunction (CMD) is a high-risk factor for a variety of cardiovascular events. Due to its complex aetiology and concealability, knowledge of the... (Review)
Review
Coronary microvascular dysfunction (CMD) is a high-risk factor for a variety of cardiovascular events. Due to its complex aetiology and concealability, knowledge of the pathophysiological mechanism of CMD is still limited at present, which greatly restricts its clinical diagnosis and treatment. Studies have shown that CMD is closely related to a variety of cardiovascular diseases, can aggravate the occurrence and development of cardiovascular diseases, and is closely related to a poor prognosis in patients with cardiovascular diseases. Improving coronary microvascular remodelling and increasing myocardial perfusion might be promising strategies for the treatment of cardiovascular diseases. In this paper, the pathogenesis and functional assessment of CMD are reviewed first, along with the relationship of CMD with cardiovascular diseases. Then, the latest strategies for the treatment of CMD and cardiovascular diseases are summarized. Finally, urgent scientific problems in CMD and cardiovascular diseases are highlighted and future research directions are proposed to provide prospective insights for the prevention and treatment of CMD and cardiovascular diseases in the future.
Topics: Humans; Cardiovascular Diseases; Coronary Circulation; Myocardial Ischemia; Microcirculation
PubMed: 37321056
DOI: 10.1016/j.biopha.2023.115011 -
Function (Oxford, England) 2023When exercising humans increase their oxygen uptake (V̇O) 20-fold above rest the numbers are staggering: Each minute the O transport system - lungs, cardiovascular,... (Review)
Review
When exercising humans increase their oxygen uptake (V̇O) 20-fold above rest the numbers are staggering: Each minute the O transport system - lungs, cardiovascular, active muscles - transports and utilizes 161 sextillion (10 ) O molecules. Leg extension exercise increases the quadriceps muscles' blood flow 100-times; transporting 17 sextillion O molecules per kilogram per minute from microcirculation (capillaries) to mitochondria powering their cellular energetics. Within these muscles, the capillary network constitutes a prodigious blood-tissue interface essential to exchange O and carbon dioxide requisite for muscle function. In disease, microcirculatory dysfunction underlies the pathophysiology of heart failure, diabetes, hypertension, pulmonary disease, sepsis, stroke and senile dementia. Effective therapeutic countermeasure design demands knowledge of microvascular/capillary function in health to recognize and combat pathological dysfunction. Dated concepts of skeletal muscle capillary (from the Latin meaning 'hair') function prevail despite rigorous data-supported contemporary models; hindering progress in the field for future and current students, researchers and clinicians. Following closely the 100th anniversary of August Krogh's 1920 Nobel Prize for capillary function this Evidence Review presents an anatomical and physiological development of this dynamic field: Constructing a scientifically defensible platform for our current understanding of microcirculatory physiological function in supporting blood-mitochondrial O transport. New developments include: 1. Putative roles of red blood cell aquaporin and rhesus channels in determining tissue O diffusion. 2. Recent discoveries regarding intramyocyte O transport. 3. Developing a comprehensive capillary functional model for muscle O delivery-to-V̇O matching. 4. Use of kinetics analysis to discriminate control mechanisms from collateral or pathological phenomena.
Topics: Humans; Oxygen; Microcirculation; Capillaries; Oxygen Consumption; Muscle, Skeletal; Mitochondria
PubMed: 37168497
DOI: 10.1093/function/zqad013 -
Hypertension (Dallas, Tex. : 1979) Mar 2022Microcirculation and macrocirculation are tightly interconnected into a dangerous cross-link in hypertension. Small artery damage includes functional (vasoconstriction,... (Review)
Review
Microcirculation and macrocirculation are tightly interconnected into a dangerous cross-link in hypertension. Small artery damage includes functional (vasoconstriction, impaired vasodilatation) and structural abnormalities (mostly inward eutrophic remodeling). These abnormalities are major determinants of the increase in total peripheral resistance and mean blood pressure (BP) in primary hypertension, which in the long term induces large artery stiffening. In turn, large artery stiffening increases central systolic and pulse pressures, which are further augmented by wave reflection in response to the structural alterations in small resistance arteries. Finally, transmission of high BP and flow pulsatility to small resistance arteries further induces functional and structural abnormalities, thus leading to increased total peripheral resistance and mean BP, thus perpetuating the vicious circle. Hyperpulsatility, in addition to higher mean BP, exaggerates cardiac, brain, and kidney damages and leads to cardiovascular, cerebral, and renal complications. The dangerous cross-link between micro and macrocirculation can be reversed into a virtuous one by ACE (angiotensin-converting enzyme) inhibitors, sartans, and calcium channel blockers. These three pharmacological classes are more potent than β-blockers and diuretics for reducing arterial stiffness and small artery remodeling. The same ranking was observed for their effectiveness at reducing left ventricular hypertrophy, preserving glomerular filtration rate, and preventing dementia, suggesting that they can act beyond brachial BP reduction, by breaking the micro/macrocirculation vicious circle.
Topics: Blood Pressure; Humans; Hypertension; Microcirculation; Pulse Wave Analysis; Vascular Resistance; Vascular Stiffness
PubMed: 34984924
DOI: 10.1161/HYPERTENSIONAHA.121.17962 -
Microcirculation (New York, N.Y. : 1994) Jan 2017This issue of microcirculation focusses on the special topic of "microvessels of the heart" and contains five state-of-the-art reviews and one expert article that...
This issue of microcirculation focusses on the special topic of "microvessels of the heart" and contains five state-of-the-art reviews and one expert article that reflect current efforts to address the major gaps in our understanding of these key microvessels. In the adult heart, most attention until recently (especially among the clinical cardiology community) has been given to the main coronary arteries, which are the culprit vessels in patients with coronary artery disease, including its most serious manifestation, acute MI. However, due to major advances in efficiently reopening the acutely blocked coronary arteries, MI is no longer the killer disease it once was. In contrast, there are few treatment options for patients who develop microvascular obstruction during acute MI. Indeed, we have a very poor understanding of this disease, or even how heart vessels are initially formed in development. This is surprising in light of the essential nature of the cardiac microvessels for efficient cardiac function throughout life. The articles in this issue are from six keynote speakers at the 66th annual meeting of the BMS at Newcastle University and review our understanding of these key vessels from initial development to their role in adult heart disease.
Topics: Coronary Artery Disease; Coronary Circulation; Humans; Microcirculation; Regeneration
PubMed: 27926994
DOI: 10.1111/micc.12338 -
Comprehensive Physiology Dec 2017The microvasculature plays a central role in the pathophysiology of hemorrhagic shock and is also involved in arguably all therapeutic attempts to reverse or minimize... (Review)
Review
The microvasculature plays a central role in the pathophysiology of hemorrhagic shock and is also involved in arguably all therapeutic attempts to reverse or minimize the adverse consequences of shock. Microvascular studies specific to hemorrhagic shock were reviewed and broadly grouped depending on whether data were obtained on animal or human subjects. Dedicated sections were assigned to microcirculatory changes in specific organs, and major categories of pathophysiological alterations and mechanisms such as oxygen distribution, ischemia, inflammation, glycocalyx changes, vasomotion, endothelial dysfunction, and coagulopathy as well as biomarkers and some therapeutic strategies. Innovative experimental methods were also reviewed for quantitative microcirculatory assessment as it pertains to changes during hemorrhagic shock. The text and figures include representative quantitative microvascular data obtained in various organs and tissues such as skin, muscle, lung, liver, brain, heart, kidney, pancreas, intestines, and mesentery from various species including mice, rats, hamsters, sheep, swine, bats, and humans. Based on reviewed findings, a new integrative conceptual model is presented that includes about 100 systemic and local factors linked to microvessels in hemorrhagic shock. The combination of systemic measures with the understanding of these processes at the microvascular level is fundamental to further develop targeted and personalized interventions that will reduce tissue injury, organ dysfunction, and ultimately mortality due to hemorrhagic shock. Published 2018. Compr Physiol 8:61-101, 2018.
Topics: Animals; Disease Models, Animal; Humans; Microcirculation; Microvessels; Oxygen Consumption; Shock, Hemorrhagic
PubMed: 29357125
DOI: 10.1002/cphy.c170006 -
Critical Care Nursing Clinics of North... Sep 2014The cardiovascular system (macrocirculation) circulates blood throughout the body, but the microcirculation is responsible for modifying tissue perfusion and adapting it... (Review)
Review
The cardiovascular system (macrocirculation) circulates blood throughout the body, but the microcirculation is responsible for modifying tissue perfusion and adapting it to metabolic demand. Hemodynamic assessment and monitoring of the critically ill patient is typically focused on global measures of oxygen transport and utilization, which do not evaluate the status of the microcirculation. Despite achievement and maintenance of global hemodynamic and oxygenation goals, patients may develop microcirculatory dysfunction with associated organ failure. A thorough understanding of the microcirculatory system under physiologic conditions will assist the clinician in early recognition of microcirculatory dysfunction in impending and actual disease states.
Topics: Hemodynamics; Humans; Microcirculation; Oxygen; Oxygen Consumption; Regional Blood Flow
PubMed: 25169685
DOI: 10.1016/j.ccell.2014.04.006 -
The Veterinary Clinics of North... Nov 2017Skin grafts and free skin flaps are useful options for closure of wounds in which primary closure or use of traditional skin flaps is not feasible. Grafts are classified... (Review)
Review
Skin grafts and free skin flaps are useful options for closure of wounds in which primary closure or use of traditional skin flaps is not feasible. Grafts are classified by their morphology and host-donor relationship. Free skin flaps with microvascular anastomoses are developed from previously described axial pattern flaps and have the added advantage of reestablishing robust vascular supply to the flap, but require specialized equipment and a high degree of technical expertise. Despite intensive perioperative care and the risk of graft or flap failure, skin grafts and free skin flaps can serve as rewarding methods of closing difficult wounds.
Topics: Animals; Microcirculation; Postoperative Complications; Skin; Skin Transplantation; Surgical Flaps; Wound Healing
PubMed: 28802984
DOI: 10.1016/j.cvsm.2017.06.009