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The Korean Journal of Hepatology Dec 2010Portal hypertension (PHT) is associated with hemodynamic changes in intrahepatic, systemic, and portosystemic collateral circulation. Increased intrahepatic resistance... (Review)
Review
Portal hypertension (PHT) is associated with hemodynamic changes in intrahepatic, systemic, and portosystemic collateral circulation. Increased intrahepatic resistance and hyperdynamic circulatory alterations with expansion of collateral circulation play a central role in the pathogenesis of PHT. PHT is also characterized by changes in vascular structure, termed vascular remodeling, which is an adaptive response of the vessel wall that occurs in response to chronic changes in the environment such as shear stress. Angiogenesis, the formation of new blood vessels, also occurs with PHT related in particular to the expansion of portosystemic collateral circulation. The complementary processes of vasoreactivity, vascular remodeling, and angiogenesis represent important targets for the treatment of portal hypertension. Systemic and splanchnic vasodilatation can induce hyperdynamic circulation which is related with multi-organ failure such as hepatorenal syndrome and cirrhotic cadiomyopathy.
Topics: Collateral Circulation; Endothelial Cells; Hemodynamics; Hepatic Stellate Cells; Hypertension, Portal; Liver Circulation; Liver Cirrhosis; Splanchnic Circulation
PubMed: 21415576
DOI: 10.3350/kjhep.2010.16.4.347 -
Pharmacology & Therapeutics 1990In recent years, knowledge of the physiology and pharmacology of hepatic circulation has grown rapidly. Liver microcirculation has a unique design that allows very... (Review)
Review
In recent years, knowledge of the physiology and pharmacology of hepatic circulation has grown rapidly. Liver microcirculation has a unique design that allows very efficient exchange processes between plasma and liver cells, even when severe constraints are imposed upon the system, i.e. in stressful situations. Furthermore, it has been recognized recently that sinusoids and their associated cells can no longer be considered only as passive structures ensuring the dispersion of molecules in the liver, but represent a very sophisticated network that protects and regulates parenchymal cells through a variety of mediators. Finally, vascular abnormalities are a prominent feature of a number of liver pathological processes, including cirrhosis and liver cell necrosis whether induced by alcohol, ischemia, endotoxins, virus or chemicals. Although it is not clear whether vascular lesions can be the primary events that lead to hepatocyte injury, the main interest of these findings is that liver microcirculation could represent a potential target for drug action in these conditions.
Topics: Animals; Humans; Liver; Liver Circulation; Liver Diseases
PubMed: 2203072
DOI: 10.1016/0163-7258(90)90091-f -
HPB Surgery : a World Journal of... Sep 1991The study of hepatic haemodynamics is of importance in understanding both hepatic physiology and disease processes as well as assessing the effects of portosystemic... (Review)
Review
The study of hepatic haemodynamics is of importance in understanding both hepatic physiology and disease processes as well as assessing the effects of portosystemic shunting and liver transplantation. The liver has the most complicated circulation of any organ and many physiological and pathological processes can affect it. This review surveys the methods available for assessing liver blood flow, examines the different parameters being measured and outlines problems of applicability and interpretation for each technique. The classification of these techniques is to some extent arbitrary and several so called "different" methods may share certain common principles. The methods reviewed have been classified into two groups (Table 1): those primarily reflecting flow through discrete vessels or to the whole organ and those used to assess local microcirculatory blood flow. All techniques have their advantages and disadvantages and in some situations a combination may provide the most information. In addition, because of the many factors affecting liver blood flow and sinusoidal perfusion, readings in a single subject may vary depending on positioning, recent food intake, anxiety, anaesthesia and drug therapy. This must be borne in mind if different studies are to be meaningfully compared.
Topics: Angiography; Dye Dilution Technique; Humans; Lasers; Liver Circulation; Magnetic Resonance Imaging; Microspheres; Radionuclide Angiography; Radionuclide Imaging; Ultrasonics; Ultrasonography
PubMed: 1931785
DOI: 10.1155/1991/68915 -
Anatomical Record (Hoboken, N.J. : 2007) Jun 2008Sepsis causes significant alterations in the hepatic macro- and microcirculation. Diverging views exist on global hepatic blood flow during experimental sepsis because... (Review)
Review
Sepsis causes significant alterations in the hepatic macro- and microcirculation. Diverging views exist on global hepatic blood flow during experimental sepsis because of the large variety in animal and sepsis models. Fluid-resuscitated clinical sepsis is characterized by ongoing liver ischemia due to a defective oxygen extraction despite enhanced perfusion. The effects of vasoactive agents on the hepatosplanchnic circulation are variable, mostly anecdotal, and depend on baseline perfusion, time of drug administration, and use of concomitant medication. Microvascular blood flow disturbances are thought to play a pivotal role in the development of sepsis-induced multiorgan failure. Redistribution of intrahepatic blood flow in concert with a complex interplay between sinusoidal endothelial cells, liver macrophages, and passing leukocytes lead to a decreased perfusion and blood flow velocity in the liver sinusoids. Activation and dysfunction of the endothelial cell barrier with subsequent invasion of neutrophils and formation of microthrombi further enhance liver tissue ischemia and damage. Substances that regulate (micro)vascular tone, such as nitric oxide, endothelin-1, and carbon monoxide, are highly active during sepsis. Possible interactions between these mediators are not well understood, and their therapeutic manipulation produces equivocal or disappointing results. Whether and how standard resuscitation therapy influences the hepatic microvascular response to sepsis is unknown. Indirect evidence supports the concept that improving the microcirculation may prevent or ameliorate sepsis-induced organ failure.
Topics: Animals; Carbon Monoxide; Endothelin-1; Humans; Liver; Liver Circulation; Microcirculation; Multiple Organ Failure; Nitric Oxide; Sepsis; Shock, Septic; Splanchnic Circulation
PubMed: 18484618
DOI: 10.1002/ar.20646 -
Anais Da Academia Brasileira de Ciencias Sep 2009Portal hypertension is the most common complication of chronic liver diseases, such as cirrhosis. The increased intrahepatic vascular resistance seen in hepatic disease... (Review)
Review
Portal hypertension is the most common complication of chronic liver diseases, such as cirrhosis. The increased intrahepatic vascular resistance seen in hepatic disease is due to changes in cellular architecture and active contraction of stellate cells. In this article, we review the historical aspects of the kallikrein-kinin system, the role of bradykinin in the development of disease, and our main findings regarding the role of this nonapeptide in normal and experimental models of hepatic injury using the isolated rat liver perfusion model (mono and bivascular) and isolated liver cells. We demonstrated that: 1) the increase in intrahepatic vascular resistance induced by bradykinin is mediated by B2 receptors, involving sinusoidal endothelial and stellate cells, and is preserved in the presence of inflammation, fibrosis, and cirrhosis; 2) the hepatic arterial hypertensive response to bradykinin is calcium-independent and mediated by eicosanoids; 3) bradykinin does not have vasodilating effect on the pre-constricted perfused rat liver; and, 4) after exertion of its hypertensive effect, bradykinin is degraded by angiotensin converting enzyme. In conclusion, the hypertensive response to BK is mediated by the B2 receptor in normal and pathological situations. The B1 receptor is expressed more strongly in regenerating and cirrhotic livers, and its role is currently under investigation.
Topics: Animals; Humans; Hypertension, Portal; Kallikrein-Kinin System; Liver Circulation; Peptidyl-Dipeptidase A; Rats; Receptor, Bradykinin B1; Receptor, Bradykinin B2; Vascular Resistance; Vasoconstriction
PubMed: 19722013
DOI: 10.1590/s0001-37652009000300008 -
Journal of Nuclear Medicine : Official... Mar 2012Several physiologic features make interpretation of PET studies of liver physiology an exciting challenge. As with other organs, hepatic tracer kinetics using PET is... (Review)
Review
Several physiologic features make interpretation of PET studies of liver physiology an exciting challenge. As with other organs, hepatic tracer kinetics using PET is quantified by dynamic recording of the liver after the administration of a radioactive tracer, with measurements of time-activity curves in the blood supply. However, the liver receives blood from both the portal vein and the hepatic artery, with the peak of the portal vein time-activity curve being delayed and dispersed compared with that of the hepatic artery. The use of a flow-weighted dual-input time-activity curve is of importance for the estimation of hepatic blood perfusion through initial dynamic PET recording. The portal vein is inaccessible in humans, and methods of estimating the dual-input time-activity curve without portal vein measurements are being developed. Such methods are used to estimate regional hepatic blood perfusion, for example, by means of the initial part of a dynamic (18)F-FDG PET/CT recording. Later, steady-state hepatic metabolism can be assessed using only the arterial input, provided that neither the tracer nor its metabolites are irreversibly trapped in the prehepatic splanchnic area within the acquisition period. This is used in studies of regulation of hepatic metabolism of, for example, (18)F-FDG and (11)C-palmitate.
Topics: Algorithms; Animals; Bile Acids and Salts; Fatty Acids; Galactose; Glucose; Hepatic Artery; Humans; Liver; Liver Circulation; Metabolic Clearance Rate; Microcirculation; Models, Biological; Portal Vein; Positron-Emission Tomography; Radiopharmaceuticals
PubMed: 22323781
DOI: 10.2967/jnumed.111.100214 -
British Journal of Anaesthesia May 1992
Topics: Biological Availability; Humans; Liver; Liver Circulation; Liver Diseases; Xenobiotics
PubMed: 1642932
DOI: 10.1093/bja/68.5.459 -
Updates in Surgery Sep 2023Post-resective liver failure is a frequent complication of liver surgery and it is due to portal hyperperfusion of the remnant liver and to arterial vasoconstriction, as...
Post-resective liver failure is a frequent complication of liver surgery and it is due to portal hyperperfusion of the remnant liver and to arterial vasoconstriction, as buffer response of the hepatic artery. In this context, splenectomy allows a reduction of portal flow and increases the survival chance in preclinical models. SerpinB3 is over-expressed in the liver in oxidative stress conditions, as a mechanism of cell defense to provide survival by apoptosis inhibition and cell proliferation. In this study, the expression of SerpinB3 was assessed as predictor of liver damage in in vivo models of major hepatic resection with or without splenectomy. Wistar male rats were divided into 4 groups: group A received 30% hepatic resection, group B > 60% resection, group C > 60% resection with splenectomy and group D sham-operated. Before and after surgery liver function tests, echo Doppler ultrasound and gene expression were assessed. Transaminase values and ammonium were significantly higher in groups that underwent major hepatic resection. Echo Doppler ultrasound showed the highest portal flow and resistance of the hepatic artery in the group with > 60% hepatectomy without splenectomy, while the association of splenectomy determined no increase in portal flow and hepatic artery resistance. Only the group of rats without splenectomy showed higher shear-stress conditions, reflected by higher levels of HO-1, Nox1 and of Serpinb3, the latter associated with an increase of IL-6. In conclusion, splenectomy controls inflammation and oxidative damage, preventing the expression of Serpinb3. Therefore, SerpinB3 can be considered as a marker of post-resective shear stress.
Topics: Male; Rats; Animals; Rats, Wistar; Liver Circulation; Liver; Hepatectomy; Hepatic Artery; Splenectomy
PubMed: 37204659
DOI: 10.1007/s13304-023-01531-6 -
Critical Care (London, England) Apr 2004Excessive inflammatory responses and impaired oxygen utilization because of microcirculatory failure are implicated in septic shock. Recent studies have pointed out some...
Excessive inflammatory responses and impaired oxygen utilization because of microcirculatory failure are implicated in septic shock. Recent studies have pointed out some beneficial effects in the treatment of septic shock of several vasodilators that exert anti-inflammatory properties. In particular, the antioxidant N-acetylcysteine has been demonstrated to enhance cardiac performance, and to improve hepatosplanchnic perfusion and liver function in patients with established septic shock. These clinical observations may lead us to examine further the role of antioxidant agents in developing novel therapies for septic shock.
Topics: Acetylcysteine; Antioxidants; Hemodynamics; Humans; Lidocaine; Liver; Liver Circulation; Shock, Septic
PubMed: 15025765
DOI: 10.1186/cc2450 -
Anatomical Record (Hoboken, N.J. : 2007) Jun 2008
Topics: Animals; Humans; Liver; Liver Circulation; Liver Diseases
PubMed: 18484605
DOI: 10.1002/ar.20682