ISSN:0009-7330    

出版商:OVID    

年代:1954

数据来源: OVID

摘要:

The acceptable zeros of the potential of the electrical fields produced by certain dipole distributions in homogeneous volume conductors is discussed. A bridge circuit is described by which a solution of the three-arm and the four-arm central terminals of Wilson may be solved for a zero of potential of the field produced by an arbitrary distribution of dipoles in a homogeneous volume conductor. An acceptable zero of potential for evaluation of the potentials in a locus on the “body” surface distant from the heart is described.

ISSN:0009-7330    

出版商:OVID    

年代:1954

数据来源: OVID

摘要:

Left ventricular dimensions have been directly measured for extended periods of time in intact unanesthetized dogs under various conditions. The diameter of the left ventricle during diastole is very large in relation to the change in diameter during each cycle. Thus, considerable quantities of blood remain within the chamber at the end of systolic ejection. The stroke output can be increased by either more complete systolic ejection during exercise or by greater diastolic filling during a startle reaction. Accelerated heart rate occurs in both cases. Changes in left ventricular diameter occur very rapidly, often being manifest within the duration of a single cardiac cycle. Mechanisms by which changes in ventricular size can be directly affected by neural and hormonal influences are briefly considered.

ISSN:0009-7330    

出版商:OVID    

年代:1954

数据来源: OVID

摘要:

Changes in heart size have been studied by means of intraventricular gages, serial roentgenography and cinefluorographic angiocardiography. Evidence is presented that the area of the cardiac silhouette and the area and diameter of the left ventricle all diminish in response to thoracotomy and during recovery return toward the pre-operative dimensions. Since fundamental concepts of cardiac function and control are based largely on investigation of exposed hearts, these concepts must be re-examined in intact, unanesthetized animals and man.

ISSN:0009-7330    

出版商:OVID    

年代:1954

数据来源: OVID

摘要:

The cold-blooded auricle under aconitine shows an early profound depression in rhythmicity but recovers in from 5 to 10 minutes to develop a high rate of spontaneous beating which may be considered a tachycardia for this preparation. Although arrhythmias do not appear spontaneously, a single, properly-timed stimulus to the auricle under aconitine initiates a multiple response which appears like ordinary fibrillation or flutter. The alterations in fundamental properties of the auricle which are required to elicit multiple responses favor a re-entrant rather than a focal mechanism of the induced arrhythmia.

ISSN:0009-7330    

出版商:OVID    

年代:1954

数据来源: OVID

摘要:

Bilateral nephrectomy selectively augments reactivity to pressor drugs and affects that to angiotonin the most prominently. This change is not mediated through the central nervous system, does not depend upon mechanical exclusion of the renal vascular bed, and is not modified by change in sodium intake. The inhibitory action on pressor responsiveness is independent of renal excretory function.

ISSN:0009-7330    

出版商:OVID    

年代:1954

数据来源: OVID

摘要:

Potassium deficiency, induced in a series of rats by dietary deprivation, was associated with a depressor response. The administration of cortisone and, to a lesser extent, of corticotropin (ACTH), promptly elevated their lowered blood pressures. The possible participation of the adrenal cortex in the depressor response to potassium deficiency is discussed.

ISSN:0009-7330    

出版商:OVID    

年代:1954

数据来源: OVID

摘要:

Simultaneous feeding of dihydrocholesterol and cholesterol to rats significantly reduced the amount of cholesterol absorbed into the thoracic lymph. Hypercholesteremia and hyperphospholipemia developed in rats simultaneously fed cholesterol and cholic acid for 8 weeks. The addition of dihydrocholesterol to this diet also decreased the rate of development and magnitude of the hypercholesteremia, but had no apparent effect upon the rise of plasma phospholipids.

ISSN:0009-7330    

出版商:OVID    

年代:1954

数据来源: OVID

摘要:

Phasic right atrial and ventricular pressures and heart sounds were simultaneously recorded from dogs with normal and ectopic ventricular contractions. Heart sounds and electrocardiograms were recorded from humans. The first heart sound is significantly delayed in the absence of atrial systole. The time between onset of the ventricular pressure rise due to ventricular contraction and the beginning of the first heart sound is minimal at normal AS-VSintervals. These findings support the view that normally the A-V valves are closed or nearly closed before ventricular systole. In ectopic ventricular beats the A-V valves are closed from an open position by ventricular contraction.

ISSN:0009-7330    

出版商:OVID    

年代:1954

数据来源: OVID

摘要:

Experimental interference with the circulation in a circumscribed tissue area, too slight to produce any manifest disturbance in itself, can strikingly alter topical reactivity to irritants and to the antiphlogistic effect of hydrocortisone. Thus, certain vascular territories can be “selectively conditioned” to the anti-inflammatory actions of blood-borne corticoids. Conversely, when tissue damage is severe, such “selective conditioning” may induce a seemingly paradoxic reversal of the hydrocortisone effect, so that the hormone enhances inflammation. Here, impairment of circulation and hydrocortisone facilitate the production by irritants of necrosis, more than of inflammation. The resulting wide-spread necrosis induces an even greater inflammatory response, despite hydrocortisone, than would have been observed without hormone treatment.

ISSN:0009-7330    

出版商:OVID    

年代:1954

数据来源: OVID