ISSN:0009-7330    

出版商:OVID    

年代:1955

数据来源: OVID

摘要:

Bioassay data obtained by the rat mesoappendix method lend themselves poorly to statistical representation. Sufficient reproducibility for quantitative estimation of the titer of vasoactive materials was achieved only with crystalline substances or purified biological extracts. Neither the duration of the displacement of epinephrine reactivity nor the magnitude of the shift in effective constrictor doses of epinephrine provided a satisfactory measure of vasoactivity in blood specimens. A prozone phenomenon, with agents such as Pitressin, histamine and ferritin was encountered with potentiating effects being elicited in high dose ranges and inhibitory effects in low dose ranges.

ISSN:0009-7330    

出版商:OVID    

年代:1955

数据来源: OVID

摘要:

The influence of the pericardium on cardiovascular phenomena has been examined and evaluated in the light of both ventricular function (modified Starling) curves and pressure-volume relationship of the pericardium. When the left ventricle is stressed, as by an increased aortic resistance, it dilates. The resulting pericardial tension limits right ventricular diastolic expansion and right ventricular work. By this mechanism pulmonary blood volume and pressures are kept at lower levels than would otherwise be present. The pericardium also protects against ventriculo-atrial regurgitation which may account for the observed descending limb of the classically conceived Starling curve.

ISSN:0009-7330    

出版商:OVID    

年代:1955

数据来源: OVID

摘要:

The effectiveness of l-epinephrine and l-norepinephrine in enhancing ventricular vulnerability has been compared in twelve dogs by obtaining fibrillation thresholds for single test stimuli. Both agents produce similar increases in vulnerability immediately following injection, and similar decreases in vulnerability at longer intervals following drug administration. These changes in vulnerability occur simultaneously with alterations of the same direction in resting excitability, and are dose-related. It is concluded that these agents have qualitatively and quantitatively similar effects on ventricular vulnerability.

ISSN:0009-7330    

出版商:OVID    

年代:1955

数据来源: OVID

摘要:

Vulnerability to ventricular fibrillation has been studied in 20 dogs by means of test stimuli of known strength and duration in order to ascertain the relationship between the vulnerable period and the recovery of excitability and to determine the effects of countershock defibrillation. The relative refractory period is found to be the only portion of the cycle during which fibrillation could be produced by this technique. Defibrillation was accomplished without producing significant changes in vulnerability or excitability.

ISSN:0009-7330    

出版商:OVID    

年代:1955

数据来源: OVID

摘要:

Systemic artery-pulmonary artery shunts have been made in dogs and the relation between pulmonary artery pressure and blood flow and the development of vascular lesions has been studied. Arteriolar medial hypertrophy and intimal proliferation are not necessarily incited by a large blood flow, but such lesions are more readily induced by an end-to-end than by an end-to-side type of shunt. Intimal proliferation is not associated with stainable alterations in elastic tissue or lipid infiltration. Vascular lesions do not readily regress when the inciting factor is removed.

ISSN:0009-7330    

出版商:OVID    

年代:1955

数据来源: OVID

ISSN:0009-7330    

出版商:OVID    

年代:1955

数据来源: OVID

摘要:

The disappearance of free cholesterol in incubated serum is inhibited in some lightly heparinized subjects. This inhibition is accentuated when an emulsion of soy bean phosphatides is added to the serum prior to incubation. The combined effect ofin vivoheparin andin vitrophosphatide is the reverse of that produced by added phosphatide alone in unheparinized serum. In a limited number of experiments, the results with crystalline lecithin resembled those produced by soy bean phosphatides, but were more pronounced.

ISSN:0009-7330    

出版商:OVID    

年代:1955

数据来源: OVID

摘要:

Femoral blood flow and arterial pressure responses to stimulation of the lumbar sympathetic chain at L3, L4 and L5 were compared with responses to intra-arterial injections of l-epinephrine and l-norepinephrine before and after progressively increasing levels of adrenergic blockade, and after atropine. The vasoconstrictor responses to nerve stimulation resembled most closely those caused by l-norepinephrine injections at all levels of blockade. Atropine blocked the dilator responses to sympathetic nerve stimulation and reduced reversal responses to l-norepinephrine injections but had no effect on the dilator responses to l-epinephrine. It is concluded that, in skeletal muscle, there are three types of vasoreceptors under autonomic control. Two of these, one constrictor and one dilator, are innervated; the third, a dilator receptor, is only under hormonal control.

ISSN:0009-7330    

出版商:OVID    

年代:1955

数据来源: OVID

摘要:

Employing the injection technic for venous distensibility determinations in intestinal loops of anesthetized dogs, an index to venomotor tone has been developed by measuring the volumes of blood required to produce specified changes in venous pressure. Application of this index in hemorrhage and shock experiments demonstrates a marked venomotor compensation to hemorrhage, and oscillations in venomotor tone correlating with the vasomotor waves in arterial blood pressure encountered in hemorrhagic hypotension. In the hypotension of shock, a serious deficiency in venomotor compensation develops, which should result in pooling of blood in the venous system and contribute significantly to the circulatory failure.

ISSN:0009-7330    

出版商:OVID    

年代:1955

数据来源: OVID