ABSTRACT
Acid-base homeostasis maintains systemic arterial pH within a narrow range. Whereas the normal range of pH for clinical laboratories is 7.35-7.45, in vivo pH is maintained within a much narrower range. In clinical and experimental settings, blood pH can vary in response to respiratory or renal impairment. This altered pH promotes changes in vascular smooth muscle tone with impact on circulation and blood pressure control. Changes in pH can be divided into those occurring in the extracellular space (pHo) and those occurring within the intracellular space (pHi), although, extracellular and intracellular compartments influence each other. Consistent with the multiple events involved in the changes in tone produced by altered pHo, including type of vascular bed, several factors and mechanisms, in addition to hydrogen ion concentration, have been suggested to be involved. The scientific literature has many reports concerning acid-base balance and endothelium function, but these concepts are not clear about acid-base disorders and their relations with the three known mechanisms of endothelium-dependent vascular reactivity: nitric oxide (NO/cGMP-dependent), prostacyclin (PGI2/cAMP-dependent) and hyperpolarization. During the last decades, many studies have been published and have given rise to confronting data on acid-base disorder and endothelial function. Therefore, the main proposal of this review is to provide a critical analysis of the state of art and incentivate researchers to develop more studies about these issues.
Subject(s)
Animals , Humans , Acid-Base Equilibrium/physiology , Blood Vessels/physiopathology , Endothelium, Vascular/physiopathology , Muscle, Smooth, Vascular/physiopathology , Vasodilation/physiology , Acidosis/metabolism , Acidosis/physiopathology , Alkalosis/metabolism , Alkalosis/physiopathology , Epoprostenol/physiology , Hydrogen-Ion Concentration , Muscle, Smooth, Vascular/metabolism , Nitric Oxide/physiologyABSTRACT
Objetivo. Revisão da filogênese e ontogênese hepáticas, do sistema microvascular hepático e da modulação do tônus deste sistema vascular por diferentes substâncias vasoativas. Método. Levantamento de artigos por meio do sistema Medline e consulta a livros-texto. Resultado. Foram selecionados 52 trabalhos publicados entre 1949, dos quais retiramos as informações a respeito de filogênese e ontogênese hepáticas, sistema microvascular hepático e mecanismos de controle do tônus vascular hepático. Conclusão. O fígado possui sistema vascular altamente especializado na promoção de mecanismos de troca entre hepatócitos e sangue. Diferentes fatores atuam continuamente sobre estruturas contrácteis deste sistema vascular adequando a perfusão do tecido hepático às necessidades homeostáticas de cada momento. O fígado é órgão eminentemente mantenedor do meio interno.
Subject(s)
Humans , Vasodilator Agents , Liver/physiology , Liver/blood supply , Phylogeny , Angiotensin II/physiology , Bradykinin/physiology , Endothelins/physiology , Epoprostenol/physiology , Homeostasis/physiology , Microcirculation , Nitric Oxide/physiologySubject(s)
Humans , Animals , Rats , Dogs , Rabbits , Arteriosclerosis/physiopathology , Endothelium, Vascular/physiology , Endothelium/physiology , Hypertension/physiopathology , Arteriosclerosis/etiology , Endothelium, Vascular/pathology , Endothelium, Vascular/physiopathology , Endothelium/physiopathology , Epoprostenol/physiology , Endothelium-Dependent Relaxing Factors/biosynthesis , Endothelium-Dependent Relaxing Factors/chemistry , Heart Failure/physiopathology , Nitric Oxide/pharmacology , Receptors, Endothelin/biosynthesis , Receptors, Endothelin/chemistryABSTRACT
Se describe la relación entre distintos eventos trombóticos y la coexistencia de cáncer oculto o conocido. Se analizan los fenómenos protrombóticos involucrados en este tipo de pacientes y las alteraciones que se producen en el sistema de coagulación y de anticoagulación. Se analiza la ayuda del laboratorio y se comenta el tratamiento específico del episodio de trombosis en los cancerosos