ISSN:0009-7330    

出版商:OVID    

年代:1958

数据来源: OVID

ISSN:0009-7330    

出版商:OVID    

年代:1958

数据来源: OVID

摘要:

Unequivocal evidence in favor of the concept that a ventricular diastolicvis a frontecontributes to ventricular filling has been established only in the following conditions: a. When the ventricle contains an abnormally small residual volume (rat, dog, turtle) b. When the ventricle contains a more nearly normal, residual volume due to ejection against the resistance of a fluid column (dog, turtle). The quantitative contribution of the ventricularvis a fronteto ventricular filling at various residual volumes and various levels of cardiac activity is still unknown. The physiological significance of diastolic suction for the return flow of blood can therefore not yet he evaluated.

ISSN:0009-7330    

出版商:OVID    

年代:1958

数据来源: OVID

摘要:

Experiments on monkeys show that their carotid sinus areas are provided with baroceptors and chemoceptors acting reflexively on circulation and respiration.

ISSN:0009-7330    

出版商:OVID    

年代:1958

数据来源: OVID

摘要:

Substances that have not exhibited properties as excitants of ectopic activity by intracoronary injection into normal hearts often produce rapid ectopic activity and sometimes ventricular fibrillation upon slow injection through the vascular bed of an infarcted area, particularly upon the first one or two injections. Sodium lactate has reduced and stopped ectopic activity for brief periods. Excesses of both potassium and calcium have increased ectopic activity in infarction and produced it in normal hearts. No antagonism between these two ions, with respect to ectopic activity, has been demonstrated.

ISSN:0009-7330    

出版商:OVID    

年代:1958

数据来源: OVID

摘要:

Anesthetized dogs were artificially cooled to temperatures at which a marked prolongation of systole was observed. Under these conditions, it was possible to identify undulations in pressure during the prolonged systole without confusion with incisural pressure changes. These pressure undulations in the aortic arch were observed to occur simultaneously with but in opposite phase relations to the primary peak and dicrotic oscillations recorded from the femoral artery. This evidence offers additional support to the standing-wave theory.

ISSN:0009-7330    

出版商:OVID    

年代:1958

数据来源: OVID

摘要:

In anesthetized dogs, the effects of hemorrhage alone upon the mesenteric circulation have been compared with those of hemorrhage plus l-norepinephrine. With norepinephrine, the portal venous flow is slightly less than in the case of untreated hemorrhage. In view of the significantly higher blood pressure during the norepinephrine infusions, however, the mesenteric resistance is considerably greater during infusions of this agent than in untreated hemorrhage.

ISSN:0009-7330    

出版商:OVID    

年代:1958

数据来源: OVID

摘要:

Measurement of blood flow through the portal vein of the dog revealed a reduction of flow and an increase in vascular resistance of the mesenteric bed in proportion to the elevation of portal venous pressure. To obtain further information on this mechanism, studies were performed on segments of terminal ileum with continuous measurement of both weight and flow. These studies demonstrated that the increase of vascular resistance was not dependent upon extrinsic or adrenergic innervation, and did not appear to be secondary to interstitial fluid formation. It is suggested that the response in this bed is due to a local reflex to a myogenic reaction of the resistance vessels to increased transmural pressure.

ISSN:0009-7330    

出版商:OVID    

年代:1958

数据来源: OVID

摘要:

Dog hearts were taken without loss of blood under 3 different conditions: (1) normally beating hearts, (2) hearts that were arrested by potassium chloride for varying lengths of time and (3) potassium chloride-arrested hearts that were reperfused with blood after varying lengths of time. In normal hearts counts of open capillaries containing erythrocytes showed a uniform distribution throughout the right myocardium and a gradient decreasing from the epicardium toward the endocardium in the left myocardium. Potassium chloride-arrested hearts showed a reverse gradient in the left myocardium. In normal hearts, erythrocytes are oriented in capillaries so that their flat sides lie against the nearest myocardial cell. In the arrested hearts, one sees few or no erythrocytes with this orientation. The erythrocytes in the arrested hearts are swollen, rounded, or packed in clumps in the capillaries. Arrested hearts exhibit a weakening of the connective tissue elements of the myocardium, evident upon fixation or on perfusion of the myocardium with blood. The weakening increases as the length of myocardial arrest increases.

ISSN:0009-7330    

出版商:OVID    

年代:1958

数据来源: OVID

摘要:

Comparisons have been made in the open chest dog of the oxygen usage of the left ventricle whose external work has been reduced to zero by 4 different procedures. The average oxygen usage of the left myocardium/100 Gm./min. is about 2.0 cc. in complete arrest with vagal stimulation or with intracoronary potassium injection; 3.8 cc. in fibrillation; and 3.4 cc. in the empty but beating heart. The oxygen value in the arrested heart approximates 27 per cent of that in the control state and the uptake during vagal stoppage varies directly with the control metabolic level. In the fibrillating ventricle the higher values are related to the intensity of fibrillatory movements, and in the empty beating heart to the control metabolic rate and to the frequency of the heart beat. The experiments with vagal arrest also permit estimation of the oxygen debt of the myocardium.

ISSN:0009-7330    

出版商:OVID    

年代:1958

数据来源: OVID