RESUMO
PURPOSE: We sought to investigate the sympathetic mechanism controlling coronary circulation during trigeminal nerve stimulation in healthy women. METHODS: The protocol consisted of 3 min of trigeminal nerve stimulation (TGS) with cold stimuli to the face, in two conditions: (1) control and ß-blockade (oral propranolol), and (2) control and α-blockade (oral prazosin). RESULTS: Thirty-one healthy young subjects (women: n = 13; men: n = 18) participated in the study. By design, TGS decreased heart rate (HR), and increased blood pressure (BP) and cardiac output (CO). Before the ß-blockade coronary blood velocity (CBV-Δ1.4 ± 1.3 cm s-1) increased along with the decrease of coronary vascular conductance index (CVCi-Δ-0.04 ± 0.04 cm s-1 mmHg-1) during TGS and the ß-blockade abolished the CBV increase and a further decrease of CVCi was observed with TGS (Δ-0.06 ± 0.07 cm s-1 mmHg-1). During the α-blockade condition before the blockade, the CBV increased (Δ0.93 ± 1.48 cm s-1) along with the decrease of CVCi (Δ-0.05 ± 1.12 cm s-1 mmHg-1) during TGS, after the α-blockade CBV (Δ0.98 ± cm s-1) and CVCi (Δ-0.03 ± 0.06 cm s-1 mmHg-1) response to TGS did not change. CONCLUSION: Coronary circulation increases during sympathetic stimulation even with a decrease in heart rate.
Assuntos
Circulação Coronária , Vasos Coronários , Masculino , Humanos , Feminino , Pressão Sanguínea/fisiologia , Velocidade do Fluxo Sanguíneo/fisiologia , Circulação Coronária/fisiologia , Vasos Coronários/inervação , Frequência Cardíaca/fisiologia , Nervo Trigêmeo , Sistema Nervoso Simpático/fisiologiaRESUMO
Vasomotor control by the sympathetic nervous system presents substantial heterogeneity within different tissues, providing appropriate homeostatic responses to maintain basal/stimulated cardiovascular function both at normal and pathological conditions. The availability of a reproducible technique for simultaneous measurement of sympathetic drive to different tissues is of great interest to uncover regional patterns of sympathetic nerve activity (SNA). We propose the association of tyrosine hydroxylase immunoreactivity (THir) with image analysis to quantify norepinephrine (NE) content within nerve terminals in arteries/arterioles as a good index for regional sympathetic outflow. THir was measured in fixed arterioles of kidney, heart, and skeletal muscle of Wistar-Kyoto rats (WKY) and spontaneously hypertensive rats (SHR) (123 ± 2 and 181 ± 4 mmHg, 300 ± 8 and 352 ± 8 beats/min, respectively). There was a differential THir distribution in both groups: higher THir was observed in the kidney and skeletal muscle (â¼3-4-fold vs. heart arterioles) of WKY; in SHR, THir was increased in the kidney and heart (2.4- and 5.3-fold vs. WKY, respectively) with no change in the skeletal muscle arterioles. Observed THir changes were confirmed by either: 1) determination of NE content (high-performance liquid chromatography) in fresh tissues (SHR vs. WKY): +34% and +17% in kidney and heart, respectively, with no change in the skeletal muscle; 2) direct recording of renal (RSNA) and lumbar SNA (LSNA) in anesthetized rats, showing increased RSNA but unchanged LSNA in SHR vs. WKY. THir in skeletal muscle arterioles, NE content in femoral artery, and LSNA were simultaneously reduced by exercise training in the WKY group. Results indicate that THir is a valuable technique to simultaneously evaluate regional patterns of sympathetic activity.
Assuntos
Fibras Adrenérgicas/metabolismo , Estruturas Animais/inervação , Estruturas Animais/fisiopatologia , Hipertensão/fisiopatologia , Sistema Nervoso Simpático/fisiologia , Sistema Nervoso Simpático/fisiopatologia , Tirosina 3-Mono-Oxigenase/metabolismo , Fibras Adrenérgicas/patologia , Estruturas Animais/irrigação sanguínea , Estruturas Animais/metabolismo , Animais , Arteríolas/inervação , Arteríolas/metabolismo , Arteríolas/patologia , Pressão Sanguínea/fisiologia , Vasos Coronários/inervação , Vasos Coronários/metabolismo , Vasos Coronários/patologia , Artéria Femoral/metabolismo , Frequência Cardíaca/fisiologia , Imuno-Histoquímica , Rim/irrigação sanguínea , Rim/inervação , Rim/metabolismo , Rim/fisiopatologia , Região Lombossacral/inervação , Região Lombossacral/fisiologia , Masculino , Músculo Esquelético/irrigação sanguínea , Músculo Esquelético/inervação , Músculo Esquelético/metabolismo , Miocárdio/metabolismo , Norepinefrina/metabolismo , Condicionamento Físico Animal/fisiologia , Ratos , Ratos Endogâmicos SHR , Ratos Endogâmicos WKY , Tirosina 3-Mono-Oxigenase/análiseRESUMO
BACKGROUND: The proximity to vascular structures is a limiting factor during radiofrequency ablation. However, little or no attention has been given to the atrial arterial circulation during the development of atrial fibrillation (AF) catheter ablation techniques. METHODS AND RESULTS: We examined the atrial arterial circulation in areas involved in AF ablation in 24 heart specimens by colored resin injection and careful dissection. The sinus node artery (SNA) arose from the circumflex artery in 42% of case; proximal to the LA appendage in 29%, crossing the left atrium (LA) anterior wall; and after the LA appendage in the remaining 13%, crossing the mitral isthmus and passing close to the left pulmonary veins (PVs), the LA roof, and the right superior PV. In 58%, the SNA arose from the right coronary artery. Major arteries (≥ 1 mm in external diameter) were found in the mitral isthmus in 54%, at the LA roof in 54%, and at the LA anterior wall in 29%. Around the left PV ostia, there were areas with major arteries in up to 37% (at the roof and inferior segments) and around the right PV ostia in up to 29% (at the roof segment). CONCLUSIONS: Major atrial coronary arteries, including the SNA, were commonly found in the areas involved in AF ablation and could cause difficulties in obtaining transmural lesions and electric isolation or even lead to ischemic sinus node or atrial dysfunction.