ABSTRACT
Antecedentes: La activación de Rho kinasa disminuye la formación de óxido nítrico al inhibir eNOS. Por otro lado, el rol de la vía de señalización RhoA/Rho kinasa en la actividad y expresión génica de la enzima clave en la vía vasodilatadora del sistema renina angiotensina (SRA), denominada ECA2, no es conocido. Objetivo: Determinar la participación de la vía RhoA/Rho kinasa en la actividad enzimática y en la expresión de ECA2 y de eNOS en la pared arterial en ratas hipertensas (DOCA-sal). Métodos: Se usaron ratas Sprague Dawley de 150 grs. unifrectomizadas tratadas con desoxicorticosterona (DOCA, 100 mg/Kg/sem sbc) durante 6 semanas. Como controles se usaron ratas unifrectomizadas. Un tercer grupo recibió DOCA y además el inhibidor específico de Rho, fasudil (100 mg/kg/día) por gavage durante 21 días. Al finalizar los tratamientos se determinó la presión arterial sistólica (PAS), la masa relativa del ventrículo izquierdo (MRVI mg*100/g), las actividades de ECA y ECA2 por fluorimetría y la expresión de genes de ECA, ECA2 y eNOS por RT-PCR en la aorta. Conclusión: La mayor expresión de ECA2 inducida por fasudil indujo un aumento significativo de la expresióngénica de eNOS en la pared arterial, lo que pudiera explicar el efecto de fasudil sobre ECA2. La inhibición de Rhokinasa activa la vía vasodilatadora del SRA en la pared arterial de ratas hipertensas aumentando los niveles de ECA2 y de eNOS, y disminuye los niveles de ECA.
Background: Through nitric oxide synthase (eNOS) inhibition, Rho-kynase decreases the formation of NO. The role of the RhoA/Rho kynase signaling pathway upon the activity and gene expression of the enzyme responsible for the vasodilating effects of the renin-angiotensin system (RAS), named ACE2 , is unknown. Aim: To determine the role of the RhoA/Rho kynase pathway on the activity and expression of ACE2 and eNOS in the arterial wall of rats with DOCA-salt induced hypertension. Methods: Sprague Dawley uninephrectomized DOCA hypertensive rats ( DOCA, 100mg/Kg/week sbc during 6 weeks) were used as controls. A third group received the specific Rho inhibitor fasudil (100 mg/Kg/day) in addition to DOCA for 21 days. At the end of the treatment period, blood pressure, relative left ventricular mass (RLVIM,mg*100/g), ACE and ACE2 activities (fluorometry) were determined. The expression of ACE and ACE2 genes, along with eNOS in the aortic wall were determined by RT-PCR. Results: Are expressed as mean +/- SEM.
Subject(s)
Animals , Rats , Arteries/enzymology , Hypertension/enzymology , Blood Pressure/physiology , Protein-Tyrosine Kinases/antagonists & inhibitors , Protein-Tyrosine Kinases/metabolism , /analogs & derivatives , /pharmacology , RNA, Messenger/physiology , Hypertrophy, Left Ventricular/enzymology , Protein Kinase Inhibitors/pharmacology , Nitric Oxide Synthase Type II , Nitric Oxide Synthase Type II/genetics , Nitric Oxide Synthase Type II/metabolism , Peptidyl-Dipeptidase A , Peptidyl-Dipeptidase A/genetics , Peptidyl-Dipeptidase A/metabolism , Rats, Sprague-Dawley , Renin-Angiotensin System/physiology , Signal Transduction , Vasodilation/physiology , Heart Ventricles/enzymologyABSTRACT
The external elastic lamina (EEL) serves as a barrier for cells and macromolecules between the media and adventitia in the vascular wall. We evaluated the morphological changes and quantitative assessments of the EEL architecture in the coronary circulation of pigs fed with a high cholesterol diet. Confocal microscopy analysis of the EEL from hypercholesterolemic coronary arteries revealed an altered pattern characterized by fragmentation and disorganization of the EEL associated with an increase in the thickness. Computerized digital analysis of the images obtained by confocal scanning microscopy demonstrated that compared to normal coronary arteries, the EEL of hypercholesterolemic coronary arteries decreased in the percentage of their elastin content (30.80 +/- 1.64% vs. 47.85 +/- 1.82%, p = 0.001). The percentage of elastin content was negatively correlated with the vessel wall area (r = -0.82, p = 0.001). The immunoreactivity for matrix metalloproteinase-3 (MMP-3) increased in cholesterol-fed coronary arteries, predominantly in the neointima and adventitia. This study demonstrates that experimental hypercholesterolemia induced ultrastructural changes of the EEL in coronary circulation. The EEL may also be an atherosclerosis-prone area compared with the intima. The EEL may play an important role in the development of structural changes which characterizes the early phase of coronary atherosclerosis and vascular remodeling.