Video Experimental Relacionado
Updated: Jul 31, 2026
12:37
Surgical Placement of Catheters for Long-term Cardiovascular Exercise Testing in Swine
Published on: February 9, 2016
La relajación dependiente del endotelio compite con la constricción alfa 1- y alfa 2-adrenérgica en la
C J Jones1, D V DeFily, J L Patterson
1Department of Medical Physiology, Texas A&M University Health Science Center, College Station 77843-1114.
Circulation
|April 1, 1993
Resumen
La relajación dependiente del endotelio modula la constricción microvascular coronaria alfa-adrenérgica. La inhibición de la sintasa de óxido nítrico potencia la vasoconstricción mediada por los receptores adrenérgicos alfa-1 y alfa-2 en el corazón latiente.
Área de la Ciencia:
- Fisiología cardiovascular fisiología cardiovascular.
- Biología Vascular Biología Vascular
- Farmacología Farmacología.
Sus antecedentes:
- Los receptores alfa-adrenérgicos juegan un papel en la regulación del flujo sanguíneo coronario.
- La relajación dependiente del endotelio influye en el tono vascular.
- La interacción entre estos mecanismos en la microcirculación coronaria requiere más investigación.
Objetivo del estudio:
- Para investigar la interacción entre la relajación dependiente del endotelio y la constricción microvascular coronaria alfa-adrenérgica.
- Para determinar si la relajación dependiente del endotelio compite con la constricción microvascular coronaria adrenérgica alfa-1 y alfa-2 in vivo.
Principales métodos:
- Utilizó epiiluminación estroboscópica y microscopía intravital para mediciones del diámetro microvascular coronario en perros.
- Los receptores adrenérgicos alfa-1 y alfa-2 activados selectivamente mediante infusiones de norepinefrina.
- Síntesis inhibida de óxido nítrico mediante el uso de NG-nitro-L-arginina (L-NA) o NG-nitro-L-arginina éster metílico (L-Nombre).
Principales resultados:
- La activación adrenérgica alfa-1 constrigió las arterias pequeñas, mientras que la activación alfa-2 constrigió las arteriolas al inicio.
- La inhibición de la síntesis de óxido nítrico potenciaba la constricción mediada por alfa-1 y alfa-2 adrenérgicos.
- Se descubrió la constricción alfa-1 en las arteriolas y la constricción alfa-2 en las arterias pequeñas después de la inhibición de la óxido nítrico sintasa.
Conclusiones:
- Los receptores alfa-adrenérgicos están presentes en toda la microcirculación coronaria.
- La relajación dependiente del endotelio modula significativamente la constricción microvascular coronaria alfa-adrenérgica.
- La función endotelial deteriorada puede aumentar la importancia de la activación alfa-adrenérgica en la resistencia microvascular coronaria durante los estados de enfermedad.
Más Videos Relacionados
08:41Assessment of Vascular Tone Responsiveness using Isolated Mesenteric Arteries with a Focus on Modulation by Perivascular Adipose Tissues
Published on: June 3, 2019
09:47Measurement of Endothelium-Dependent Vasorelaxation in the Mouse Thoracic Aorta Using Tensometric Small Volume Chamber Myography
Published on: August 12, 2022
Videos de Conceptos Relacionados
01:28Nitric Oxide Signaling Pathway
Nitric oxide (NO), an inorganic gas, acts as a potent second messenger in most animal and plant tissues. NO diffuses out of the cells that produce it and enters the neighboring cells to generate a downstream response. NO synthase (NOS) catalyzes NO production by the deamination of the amino acid arginine. There are three isoforms of NOS. Endothelial cells have endothelial NOS (eNOS), nerve and muscle cells have neuronal NOS (nNOS), and macrophages produce inducible NOS (iNOS) upon exposure to...
01:26Adrenergic Receptors: β Subtype
β-adrenoceptors have varied sensitivities towards adrenaline, noradrenaline, and isoprenaline. The order of agonist potency is as follows:
Isoprenaline > Adrenaline > Noradrenaline
Neurotransmitter binding to these receptors causes activation of adenylyl cyclase resulting in increased concentrations of cAMP and modulation of calcium ion channels within the cell. They are further classified into β1, β2, and β3 subtypes.
β1-adrenoceptors: β1-adrenoceptors have equal affinities for...
Isoprenaline > Adrenaline > Noradrenaline
Neurotransmitter binding to these receptors causes activation of adenylyl cyclase resulting in increased concentrations of cAMP and modulation of calcium ion channels within the cell. They are further classified into β1, β2, and β3 subtypes.
β1-adrenoceptors: β1-adrenoceptors have equal affinities for...
01:31Adrenergic Antagonists: ɑ and β-Receptor Blockers
Third-generation β-blockers, such as labetalol and carvedilol, represent a significant advancement in managing cardiovascular conditions. Unlike conventional β-blockers, which can induce peripheral vasoconstriction, third-generation drugs block α1 adrenoceptors. This promotes vasodilation through several mechanisms, such as increased nitric oxide production, inhibition of calcium ion entry, opening of potassium ion channels, and antioxidant action. Labetalol, for instance, is clinically...
01:18Antihypertensive Drugs: Action of Calcium Channel Blockers
Calcium ions are essential to contract smooth muscle cells in blood vessels. They enter these cells through voltage-dependent calcium channels, specifically L-type calcium channels in the cell membrane. These L-type calcium channels are integral to the excitation-contraction coupling process in smooth muscle. When a stimulus is received by smooth muscle cells, their membrane depolarizes. This alteration in membrane potential instigates the opening of L-type calcium channels. As a result,...
01:17Autoregulation of Blood Flow
Autoregulation mechanisms are characterized by their inherent capacity for self-regulation without necessitating specific nervous stimulation or endocrine control. These mechanisms facilitate the adjustment of blood flow and, therefore, perfusion specific to each tissue region. This self-regulation encompasses chemical signals and myogenic controls.
Chemical Signaling in Autoregulation
Chemical signaling operates at the precapillary sphincter level, inciting either contraction or relaxation.
Chemical Signaling in Autoregulation
Chemical signaling operates at the precapillary sphincter level, inciting either contraction or relaxation.
01:29Heart Failure II: Pathophysiology
Systolic Heart Failure and Compensatory MechanismsSystolic heart failure (also termed HFrEF, Heart Failure with Reduced Ejection Fraction) is the most prevalent type of heart filure. It results in a decreased volume of blood being pumped from the ventricle. The aortic arch and carotid sinuses have baroreceptors that detect reduced blood pressure, triggering the sympathetic nervous system (SNS) to release epinephrine and norepinephrine. Initially, this response aims to boost heart rate and...