ISSN:0009-7330    

出版商:OVID    

年代:1968

数据来源: OVID

ISSN:0009-7330    

出版商:OVID    

年代:1968

数据来源: OVID

摘要:

A cylindrical ultrasonic transducer on a catheter tip lodged in the cleft between the free wall of the right ventricle and the interventricular septum provides an easily measured echo from the posteroinferior left ventricular epicardial surface. The sonic path represents a diameter of the left ventricle at approximately its largest cross-sectional area. Experiments in six dogs demonstrated that measurements by ultrasound agree within ±6% with simultaneous radiographic measurements of left ventricular diameter. Procedures designed to alter left ventricular volume were employed in 14 dogs to clarify the physiologic meaningfulness of the left ventricular diameter measured by ultrasound. Both end-diastolic and end-systolic diameter increased with anoxia, with sudden injections of saline into the left ventricle, after propranolol, and after inflation of a balloon in the thoracic aorta. These diameters decreased with isoproterenol, with increased heart rate, and after inflation of a balloon in the inferior vena cava. The present technique provides accurate and physiologically meaningful estimates of left ventricular diameter. Ventricular diameter measurements obtained during cardiac catheterization should permit assessment of ventricular distensibility and of ventricular function.

ISSN:0009-7330    

出版商:OVID    

年代:1968

数据来源: OVID

摘要:

Norepinephrine turnover was estimated in the rat heart from the rate of release of tracer3H-norepinephrine and the depletion of endogenous norepinephrine after inhibition of synthesis. Cardiac norepinephrine turnover was markedly increased in chronically hypophysectomized rats. Thyroidectomy and adrenalectomy were also associated with increased cardiac norepinephrine turnover, whereas ovariectomy was not. Chronic treatment of hypophysectomized rats with thyroxine and ACTH restored the turnover to normal, the replacement of thyroxine being quantitatively more significant.Cardiac atrophy and decreased blood pressure occurred concomitantly with increased norepinephrine turnover in the hypophysectomized rat and were restored to normal with thyroid treatment. Ganglionic blockade of the hypophysectomized rat also restored the turnover toward normal. The metabolites of3H-norepinephrine were shifted with a decrease in O-methylated metabolites and an increase in deaminated products.This evidence suggests that thyroid deficiency and, to a lesser extent, adrenal deficiency are associated with an increase in cardiac norepinephrine turnover mediated by an increase in sympathetic nervous activity. The role of the increased turnover in relation to the hormonal deficiencies is discussed.

ISSN:0009-7330    

出版商:OVID    

年代:1968

数据来源: OVID

ISSN:0009-7330    

出版商:OVID    

年代:1968

数据来源: OVID

摘要:

The effects of hyperbaric oxygen (at 3 atmospheres absolute) on uteroplacental and fetal circulations were studied in pregnant ewes near term. The ewe was given spinal anesthesia, the fetus was marsupialized to the abdominal walls to protect the umbilical circulation, and the fetal head was covered with a saline-filled glove to prevent breathing. During hyperbaric oxygenation, maternal arterial blood PO2rose to 1,300 mm Hg while umbilical vein blood PO2rose to 300 mm Hg; umbilical arterial Po2rose to only 50 mm Hg. Maternal and fetal arterial pressures did not change significantly, but uteroplacental and umbilical flows decreased slightly. Ductus arteriosus blood flows decreased strikingly when the oxygen tension of the pulmonary blood rose; net pulmonary blood flow increased markedly because of a decrease in pulmonary vascular resistance produced by oxygen. Ascending aortic flow increased, but effective fetal cardiac output (aortic plus ductus arteriosus flows) decreased. These studies indicate that the fetal pulmonary vascular bed is sensitive to oxygen in that it undergoes vasodilatation when the oxygen tension of the blood passing through it rises; the ductus arteriosus responds to the same stimulus by constricting. Hyperbaric oxygenation seems to establish a circulatory pattern in the fetus similar to that of the early neonatal period.

ISSN:0009-7330    

出版商:OVID    

年代:1968

数据来源: OVID

摘要:

The intravenous administration of griseofulvin in doses of 3.0 mg/kg to 32 anesthetized open-chest dogs produced marked increments (43%) in isometric systolic force measured by a strain gauge. These changes were accompanied by an increase (22%) in heart rate and a decrease (25%) in blood pressure. The effect was unaltered by clamping the blood supply to and from the adrenal glands or by previous treatment with 1 mg/kg reserpine, 0.4 mg/kg propranolol HCl, 10 mg/kg hexamethonium chloride, 1 mg/kg phentolamine HCl or 2 mg/kg atropine. In 11 anesthetized open-chest rats and 7 isolated rabbit hearts, griseofulvin also increased the force of contraction. It may be inferred from these experiments that griseofulvin has a direct action on the cardiovascular system rather than one mediated through neurogenic or hormonal mechanisms. These cardiovascular changes may occur in patients in whom griseofulvin is used in the treatment of fungus diseases.

ISSN:0009-7330    

出版商:OVID    

年代:1968

数据来源: OVID

ISSN:0009-7330    

出版商:OVID    

年代:1968

数据来源: OVID

摘要:

Right and left ventricular outputs were measured by a dye dilution technique in fetal lambs before and during graded reduction of umbilical blood flow by constriction of the abdominal portion of the umbilical vein. PO2, PCO2and pH were measured on blood samples taken from the carotid artery and the ductus arteriosus. Oxygen saturation values were estimated from oxygen dissociation curves for fetal lambs' blood. With slight constriction of the umbilical vein, both ventricular outputs fell, but there was no significant difference between them for umbilical flows exceeding 150 ml/kg per min. With further reduction of umbilical flow, the output of the right ventricle fell more than that of the left. When flow was reduced to less than 120 ml/kg per min, right ventricular output was significantly higher than that of the left (P< 0.001). Oxygen saturation of blood from both the carotid artery and the ductus arteriosus fell with reduction of umbilical flow, but the difference between these values was not significantly altered. These observations show that major reduction of venous return may change the proportion in which various blood streams mix as they pass through the fetal heart.

ISSN:0009-7330    

出版商:OVID    

年代:1968

数据来源: OVID

ISSN:0009-7330    

出版商:OVID    

年代:1968

数据来源: OVID