RESUMO
The autonomic innervation in the heart is predominantly by postganglionic, parasympathetic, and sympathetic neurons, which are organized in a plexus of ganglions into the heart. The knowledge of the density, distribution, location, morphology, and intrinsic connection of this system that constitute the heart autonomic innervation is limited and controversial. Methods that provide clear information in this field are desirable. A widely used method to study the morphology of the nerve cells in the central nervous system (CNS) is used in this study to characterize the autonomic innervation in rat hearts. The method consisted of impregnation of the fresh whole heart of 12 adult male Wistar rats with the Golgi-Cox stain for 30 days, after which they were incubated in 30% sucrose solution for 2-3 days and then were sectioned (200 microm) with a vibratome. The tissues were mounted on gelatin-covered slides and analyzed by using the Sholl method under light microscopy adapted to a camera lucida. The results clearly show a distribution of the ganglion plexuses in the epicardium, myocardium, and endocardium, joined by an extensive network of nerve fibers in the four cardiac chambers. We also identified and characterized the morphology of an isolated cardiac nerve cell. As results similar to that in the CNS, the Golgi-Cox method is a simple, efficient, and an accessible tool to study the autonomic innervation in the rat heart and provides a good resolution of the morphology of the plexuses of the ganglions and nerve fibers.
Assuntos
Vias Autônomas/anatomia & histologia , Coração/inervação , Neurônios/citologia , Coloração e Rotulagem/métodos , Animais , Coração/anatomia & histologia , Masculino , Fotomicrografia , Ratos , Ratos WistarRESUMO
Pulmonary venous flow (PVF) has been analyzed by Doppler echocardiography in various cardiopathies, but up to now no studies of its behavior in acute myocardial ischemia have been reported. The purpose of this study is to describe the changes observed in the normal pattern of PVF with myocardial ischemia in an experimental model. Thoracotomy and pericardiectomy with exposure of the heart were performed on 19 mongrel dogs, weighing between 18 and 25 kg anesthetized with intravenous sodium pentobarbital. Pulmonary venous and mitral flows were analyzed by transesophageal echocardiography with pulsed Doppler and simultaneous recording of intracavitary pressures in left atrium (LA) and left ventricle (LV) before and after 30 minutes of partial occlusion of the middle portion of the anterior descending coronary artery distal to the first diagonal branch. The variables examined included maximal velocities and time-velocity integrals of antegrade systolic(s) and diastolic (D) PVF, mitral rapid filling flow (E) and left ventricular isovolumic relaxation time (LVIRT). The pressures directly measured were mean left atrial pressure (MLAP), systolic and diastolic pressures of the LV. Results included a decrease in peak velocities and time-velocity integrals of PVF (S and D) with myocardial ischemia, S velocity from 70.1 +/- 14.8 to 49.5 +/- 13.8 cm/sec (p < 0.001) and D from 41.4 +/- 16.5 to 29.5 +/- 11.4 cm/sec (p = 0.001), with an increase in LVIRT from 65.8 +/- 8.6 to 76.0 +/- 12.6 msec (p < 0.006) and elevation of the mean pressure of the LA from 4.3 +/- 1.0 to 6.4 +/- 1.5 mmHg (p < 0.001). This findings suggest that acute myocardial ischemia alters the normal pattern of PVF, producing a significant decrease in peak velocities and time-velocity integrals of antegrade systolic and diastolic flows as well as an increase in LVIRT and MLAP, which taken together may reflect altered diastolic function of the LV.
Assuntos
Ecocardiografia Transesofagiana , Isquemia Miocárdica/fisiopatologia , Circulação Pulmonar/fisiologia , Veias Pulmonares/diagnóstico por imagem , Doença Aguda , Animais , Cães , Feminino , MasculinoRESUMO
The role of testosterone/17 B estradiol ratios (T/E), on the vasoconstrictor effect of norepinephrine (NE), were studied in strips of carotid arteries from dogs. T/E of 0.1 (T = 1 nM/E = 10 nM) shifted the concentration/effect (C-E) curve of NE to the right. T/E of 10 (T = 10 nM/E = 1 nM) deviated it to the left. T (1 nM and 10 nM) shifted the C-E curve of NE to the right; E = 1 nM did not modify it; E = 10 nM, shifted it to the left. In microsomal fraction of carotid arteries, adrenergic receptors were characterized with 3H-NE binding, and the role of T/E ratios also studied. Under the influence of T/E ratio of 10, the agonist affinity (Ka), was increased from 100 nM-1 to 128 nM-1, the receptors density (Bmax), increased from 78.3 nM to 148 nM. E (1 nM) reduced Ka to 88 nM-1, T did not change any of these parameters. In conclusion, T/E ratios of 10, as in male, may enhance the vasoconstrictor activity of NE, increasing Ka and Bmax of adrenergic receptors.