RESUMEN
BACKGROUND: The spread of activation between the right atrium (RA) and left atrium (LA), particularly along the right and left aspects of the interatrial septum, is not clear. METHODS AND RESULTS: Basket-shaped catheters carrying 64 electrodes were deployed into both the RA and LA of 10 dogs. Position and orientation of the baskets were determined by fluoroscopy and echocardiography. Basket unipolar electrograms were simultaneously recorded in each dog during sinus rhythm, right ventricular pacing, and pacing of the right septum through the basket in the superior and inferior regions. Isochrone maps depicting all aspects of the atria, including the septum, were compared. During sinus rhythm and superior right septal pacing, wave fronts propagated predominantly from superior to inferior regions on both the right and left septum. However, activation of the left septum was delayed compared with the right septum. During right ventricular pacing and inferior right septal pacing, activation of the septum was discordant; 1 wave front propagated rapidly on the right septum from inferior to superior regions, whereas 2 opposing wave fronts originated on the left septum in both the superior and inferior regions. The left septum was activated predominantly by the superior wave front. Activation of the left septum was completed in a significantly shorter time during pacing of the right septum in the inferior region compared with the superior region. CONCLUSIONS: In dogs, activation of the right and left aspects of the interatrial septum is discordant. Electrical connections are present between the RA and LA in regions superior as well as inferior to the septum.
Asunto(s)
Sistema de Conducción Cardíaco/fisiología , Tabiques Cardíacos/fisiología , Animales , Estimulación Cardíaca Artificial , Perros , Ecocardiografía , Electrodos , Electrofisiología , Femenino , Fluoroscopía , Atrios Cardíacos , Tabiques Cardíacos/anatomía & histología , MasculinoRESUMEN
Venous monitoring and evaluation present a dilemma in free flap care. Duplex ultrasonography provides information on vessel flow and anatomy. This case demonstrates the use of duplex technology in identifying problems following vascular microsurgery, and it raises discussion of possible future roles for the application of duplex ultrasonography in the management of free flaps.
Asunto(s)
Complicaciones Posoperatorias/diagnóstico por imagen , Colgajos Quirúrgicos , Ultrasonografía Doppler Dúplex , Insuficiencia Venosa/diagnóstico por imagen , Anciano , Humanos , Masculino , MicrocirugiaRESUMEN
The purpose of this study was to investigate atrial myocardial blood flow in the fetus under conditions of acute right ventricular pressure load and adenosine infusion. Late gestation fetal sheep were instrumented for acute right ventricular pressure loading or adenosine infusion, and regional myocardial blood flow was measured at rest and under experimental conditions with radiolabeled microspheres and standard reference sample technique. Resting myocardial blood flow to the atria was less than half of ventricular flow per gram tissue. During the maximum tolerated pulmonary artery pressure load, right atrial peak systolic pressure rose significantly, and atrial blood flow increased 3-fold. The percentage of total myocardial blood flow received by the right atrium during maximal pressure loading increased from 4.3 +/- 1.4% to 5.9 +/- 1.6%, p < 0.05. Adenosine infusion was associated with a 4-fold increase in atrial myocardial blood flow and a 3-fold increase in ventricular and septal blood flow. The percentage of total myocardial blood flow to both atria also increased with adenosine infusion (right atrium, 3.8 +/- 0.4% to 5.4 +/- 1.3%, and left atrium, 4.2 +/- 0.8% to 6.9 +/- 2.0%, p < 0.05). We conclude the following: 1) at rest, fetal atrial myocardial blood flow is less than one half of ventricular myocardial blood flow per gram tissue; 2) fetal atrial blood flow increases more than ventricular blood flow with acute right ventricular pressure load or adenosine infusion; and 3) these data suggest that fetal atrial blood flow is regulated independently from ventricular blood flow and may be influenced by atrial work.
Asunto(s)
Circulación Coronaria/fisiología , Corazón Fetal/fisiología , Adenosina/administración & dosificación , Animales , Función Atrial , Presión Sanguínea/efectos de los fármacos , Presión Sanguínea/fisiología , Circulación Coronaria/efectos de los fármacos , Femenino , Corazón Fetal/efectos de los fármacos , Edad Gestacional , Infusiones Parenterales , Embarazo , Flujo Sanguíneo Regional/efectos de los fármacos , Flujo Sanguíneo Regional/fisiología , Ovinos , Vasodilatación/efectos de los fármacos , Vasodilatación/fisiología , Función VentricularRESUMEN
The measurement of maximal myocardial blood flow gives information about the total cross-sectional area of the coronary resistance vessels. During a continuous left atrial infusion of adenosine (60 micrograms.kg-1.min-1), maximal myocardial blood flow was measured in 4 fetuses hypoxemic for a minimum of 5-8 days (pH = 7.33 +/- 0.01, arterial PCO2 = 49.8 +/- 4.2 Torr, arterial PO2 = 16.1 +/- 1.3 Torr, and arterial concentration of O2 = 5.3 +/- 1.2 ml/dl). These data were compared with an identically instrumented group of normoxemic fetuses (n = 7) following the same study protocol (pH = 7.38 +/- 0.02, arterial PCO2 = 43.1 +/- 3.8 Torr, arterial PO2 = 19.8 +/- 2.0 Torr, and arterial concentration of O2 = 7.9 +/- 1.0 ml/dl) (P < 0.05). At comparable arterial pressures, the maximal myocardial flow (ml.min-1.100 g tissue-1) for hypoxemic vs. normoxemic fetuses was 974 +/- 273 and 630 +/- 181 for the total myocardium, 986 +/- 367 and 602 +/- 192 for the left ventricular free wall, 1,025 +/- 346 and 614 +/- 178 for the septum, and 1,231 +/- 274 and 757 +/- 269 for the right ventricular free wall, respectively (P < 0.01). These data suggest that hypoxemia in the fetus can significantly alter the coronary vascular bed, which, if confirmed, would represent an important adaptation in the developing fetus.
Asunto(s)
Circulación Coronaria , Enfermedades Fetales/fisiopatología , Feto/fisiología , Edad Gestacional , Hipoxia/fisiopatología , Animales , Enfermedad Crónica , Ovinos/embriologíaRESUMEN
BACKGROUND: It has previously been shown that the fetal right ventricle (RV) is sensitive to changes in arterial pressure and that its stroke volume is significantly reduced with acute increases in pulmonary arterial pressure. However, the myocardial blood flow (MBF) response to increases in pulmonary arterial pressure have not been investigated in the fetus. METHODS AND RESULTS: To assess whether the RV afterload sensitivity to arterial pressure is associated with limitation in MBF, seven fetal lambs were instrumented at 130 days of gestation with a pulmonary arterial occluder and intravascular catheters. RV stroke volume was measured by an electromagnetic flow probe and MBF by 15-microns labeled microspheres. MBF was determined at baseline and during incremental increases in pulmonary arterial pressure. Maximal MBF was determined in seven additional fetuses during adenosine infusion. The highest tolerated pressure was associated with a 50% reduction in RV stroke volume. The highest pulmonary arterial occlusion pressure resulted in a doubling of MBF to all regions of the heart (266 +/- 99 to 504 +/- 158, 193 +/- 69 to 387 +/- 100, and 171 +/- 66 to 338 +/- 134 ml/min/100 g for the RV, septum, and left ventricle, respectively). The best correlation for increases in both RV and global MBF was the RV heart rate-systolic pulmonary pressure product. Adenosine infusion was associated with a threefold increase in global MBF that was significantly greater than the MBF achieved during pulmonary arterial occlusion. CONCLUSIONS: The fetal RV sensitivity to acute pressure loading is not associated with limitation of MBF. The fetal myocardium has a remarkable flow reserve that allows for preservation of function during acute increases in arterial pressure.
Asunto(s)
Presión Sanguínea/fisiología , Circulación Coronaria/fisiología , Corazón Fetal/fisiología , Función Ventricular Derecha/fisiología , Adenosina/farmacología , Animales , Circulación Coronaria/efectos de los fármacos , Femenino , Microesferas , Embarazo , Arteria Pulmonar/fisiología , Ovinos , Volumen Sistólico/fisiología , Resistencia Vascular/fisiologíaRESUMEN
To determine if the inhibitory effects of hyperprolactinemia on sexual arousal and serum LH levels could be dissociated from those on erectile function, copulatory behavior was examined in pituitary-grafted, adrenalectomized male rats that had been castrated and given 20mm subcutaneous testosterone implants. Whereas transplantation of three pituitaries under the kidney capsules inhibited mounting rates in intact animals, pituitary grafting did not significantly reduce mounting rates in the adrenalectomized group beyond the effect of adrenalectomy alone. In contrast, the effects of pituitary grafting on erectile function were enhanced in the adrenalectomized animals. Hyperprolactinemia also caused a significant reduction in serum LH, but only in the intact animals. These results suggest that: 1. the effects of hyperprolactinemia on erectile function occur independently from those on sexual arousal, and 2. the inhibitory effects of hyperprolactinemia on sexual arousal are linked to the effects of hyperprolactinemia on LH release.
Asunto(s)
Hiperprolactinemia/fisiopatología , Hormona Luteinizante/metabolismo , Erección Peniana , Adrenalectomía , Animales , Peso Corporal , Enfermedad Crónica , Hormona Luteinizante/sangre , Masculino , Erección Peniana/efectos de los fármacos , Hipófisis/trasplante , Prolactina/sangre , Prolactina/metabolismo , Ratas , Ratas Endogámicas F344 , Testosterona/farmacologíaRESUMEN
The ratio of superoxide production to oxidation of NADPH affected by the NADPH:O2 oxidoreductase of human neutrophils is strongly influenced by pH, NADPH substrate concentration, aging of the enzyme, or its exposure to excess deoxycholate. Freshly prepared enzyme exhibited a Km for NADPH of 52 microM as determined by assaying NADPH oxidase activity, or approximately 33 microM by measurement of superoxide formation. In the range of 100-150 microM NADPH at pH 7.6 and in the presence of 0.06% deoxycholate, the univalent flux of electron equivalents given up by NADPH to O2 was 99%. Following storage of the oxidoreductase overnight on ice, its Km for NADPH rose to 125 microM as determined by monitoring oxidation of NADPH but was unaltered when measured in terms of superoxide production. Concomitantly, its capacity to affect univalent reduction of O2 fell approximately 20-30% under the same assay conditions. Univalent flux rates of less than 40% were observed with exposure of the enzyme to concentrations of deoxycholate in excess of 0.1% or to pH values below 6.0 or above 8.0. The capacity of the enzyme to carry out univalent reduction fell with increasing NADPH concentrations in a manner resembling that previously reported with increasing concentrations of xanthine in the case of xanthine oxidase (Fridovich, I. (1970) J. Biol. Chem. 245, 4053-4057). The reduced form of the neutrophil oxidoreductase, like xanthine oxidase, thus appears to be capable of conducting both 1- and 2-electron transfer steps in reducing O2. Its capacity to affect univalent reduction of O2 depends upon the concentration of electron donor (NADPH) supplied as well as conditions of storage and assay of the native enzyme.
Asunto(s)
NADH NADPH Oxidorreductasas/sangre , NADPH Oxidasas , Neutrófilos/enzimología , Oxígeno/sangre , Ácido Desoxicólico/farmacología , Humanos , Concentración de Iones de Hidrógeno , Cinética , Oxidación-Reducción , Consumo de Oxígeno , Superóxidos/sangreRESUMEN
Intrinsic NADPH diaphorase activity is a component of the membrane-bound NAD(P)H:O2 oxidoreductase of human neutrophils. NADH-specific diaphorase activity is also present in membrane fractions rich in oxidoreductase activity. Studies were undertaken to determine whether the NADH diaphorase might also be intrinsic to the oxidoreductase. The latter diaphorase was freed from the membrane by detergent extraction and partially purified approximately 80-fold. Its apparent molecular weight following solubilization in deoxycholate and Tween-20 was 204 000 +/- 10 000. The specific activity of the partially purified diaphorase with ferricyanide as electron acceptor was 7.6 X 10(3) mU/mg protein, its pH optimum was 7.0, and its Km for NADH was 13 microM. It is completely devoid of NADPH diaphorase activity, lacks the capacity to reduce molecular oxygen, yet readily reduces ferricyanide, 2,6-dichlorophenolindophenol and ferricytochrome c. Whereas the NADH diaphorase was freed from the particulate fraction of cell lysates by extraction in 10 mM Tris-HCl buffer (pH 8.6) made up in 15% glycerol and 0.5% Tween-20, NADPH-dependent diaphorase and superoxide-generating activities also present in the membrane were not. These observations make it unlikely that the principal membrane-bound NADH diaphorase found in human neutrophils is a component of the NAD(P)H:O2 oxidoreductase, despite its common association in the same particulate fraction of cell lysates.
Asunto(s)
Dihidrolipoamida Deshidrogenasa/aislamiento & purificación , NADH NADPH Oxidorreductasas/aislamiento & purificación , NADPH Oxidasas , Neutrófilos/enzimología , Cromatografía en Gel , Cromatografía por Intercambio Iónico , Ácido Desoxicólico/farmacología , Dihidrolipoamida Deshidrogenasa/metabolismo , Humanos , Cinética , Peso Molecular , NADH NADPH Oxidorreductasas/metabolismo , Polisorbatos , Acetato de Tetradecanoilforbol/farmacologíaRESUMEN
At approximately equimolar concentrations (approximately 70 microM), and in the presence of excess catalase and superoxide dismutase, DCIP, ferricytochrome c and ferricyanide abstracted 21, 6 and 61%, respectively, of the electron equivalents given up by NADPH to the NADPH-O2 oxidoreductase complex derived from phorbol myristate acetate-stimulated human neutrophils. With a 10-fold increase in ferricyanide, all of the electron equivalents given up by NADPH to the oxidoreductase complex were shunted to ferricyanide concomitant with complete inhibition of NADPH-dependent O2 consumption. These results substantiate the existence of intrinsic diaphorase activity associated with the superoxide generating NADPH-O2 oxidoreductase of human neutrophils.
Asunto(s)
NADH NADPH Oxidorreductasas/sangre , NADPH Deshidrogenasa/sangre , NADPH Oxidasas , Neutrófilos/enzimología , Ferricianuros/farmacología , Humanos , Cinética , NADH NADPH Oxidorreductasas/aislamiento & purificación , NADPH Deshidrogenasa/aislamiento & purificación , Neutrófilos/efectos de los fármacos , Consumo de Oxígeno/efectos de los fármacosRESUMEN
Four catalytic components of the NADPH-dependent O2- generating oxidoreductase of human neutrophils have been identified. DCIP reductase, cytochrome c reductase and a chromophore 450-455 reductase are present in phorbol myristate acetate stimulated neutrophils and absent in resting cells and phorbol myristate acetate stimulated chronic granulomatous disease cells. Quinol dehydrogenase activity has also been demonstrated in activated and resting cells. Furthermore, a chromophore absorbing in the reduced state at 450-455 nm participates in superoxide production. This chromophore is reduced by NADPH or duroquinol and is missing in cell lysates derived from a patient with chronic granulomatous disease.
Asunto(s)
NADH NADPH Oxidorreductasas/sangre , NADPH Oxidasas , Neutrófilos/enzimología , Reductasas del Citocromo/sangre , Enfermedad Granulomatosa Crónica/enzimología , Humanos , Cinética , NADH NADPH Oxidorreductasas/aislamiento & purificación , Neutrófilos/efectos de los fármacos , Quinona Reductasas/sangre , Valores de Referencia , Superóxidos/sangre , Acetato de Tetradecanoilforbol/farmacologíaRESUMEN
NADPH-dependent O2- generating oxidoreductase activity recovered from cell lysates of phorbol myristate acetate-stimulated human neutrophils exhibits dependence on Ca+2 and Mg+2 for full expression of its catalytic activity. O2- generating activity was completely abolished by exposure of the oxidoreductase to EDTA, then reconstituted by exposure of the enzyme to Ca+2 and Mg+2 in excess of the EDTA concentration used to block catalytic activity. The oxidoreductase responded maximally to either 0.25 mM Ca+2 or 0.80 mM Mg+2. The pH optimum of the oxidoreductase exposed to Ca+2 and Mg+2 is between pH 7.0 and 7.6. The molar ratio of NADPH oxidation to O2- production determined at pH 7.6 in the presence of Ca+2 and Mg+2 is 0.49, indicating 1 mole of NADPH oxidized per 2 moles of O2- formed. Particulate fractions recovered from cell lysates of resting neutrophils exhibited no oxidoreductase activity under the same conditions.