ISSN:0009-7330    

出版商:OVID    

年代:1960

数据来源: OVID

摘要:

Comparative physiology has much to contribute to our understanding of the circulation. For this purpose large animals until recently have been neglected as subjects of circulatory studies by modern technics, yet nature's means of solving the circulatory problems which these animals present are of great interest and, in case of domestic cattle (Bos taurus), of obvious practical importance. Intravascular and intracardiac pressures were recorded, and cardiac output and related functions were measured, or calculated, and related to body size. The effects of environmental stimuli and of phonation (“moo”) were observed. Interesting differences between the findings in the cow and those in normal man and in the giraffe are made the subject of comment.

ISSN:0009-7330    

出版商:OVID    

年代:1960

数据来源: OVID

摘要:

The pathologic changes in the aorta, liver, and adrenal glands, and the changes in sterols of plasma and liver induced in birds by the prolonged feeding of a diet containing 0.5 per cent Δ4-cholestenone are described. Lesions were found in the media of thoracic aortas and intima of the abdominal aortas of the sterol-fed birds and evidence is presented to show that the crystalline material in the abdominal plaques is not cholesterol. There was enlargement of both liver and adrenal glands with a pronounced deposition of total digitonin-precipitable sterols which could not be accounted for by Liebermann-Burchard reacting sterols (LBRS). In the Δ4-cholestenone-fed birds the level of LBRS in plasma, fell to about 50 per cent of that in control birds, whereas the levels of total digitonin-precipitable sterols (TDPS) rose to values of 200 mg. per 100 ml. The fraction of the TDPS present as non-LBRS was quite constant in the plasma of the sterol-fed birds (63–69 per cent). By means of isotope dilution procedures the non-LBRS in the livers of sterol-fed birds was identified as dihydrocholesterol.

ISSN:0009-7330    

出版商:OVID    

年代:1960

数据来源: OVID

摘要:

Conventional electrocardiographie equipment (capacitance-coupled amplification) cannot distinguish between RS-T segment and baseline shifts of the ventricular complex. The so-called RS-T segment displacement is the net difference between the undetermined levels of those components. Using direct-coupled amplification, the absolute changes of baseline and RS-T segment on the surface of the exposed left ventricle during levarterenol administration and during regional ischemia, and release-recovery were studied in dogs. Ten significant patterns of displacement were observed. These permitted clear differentiation of the effects of levarterenol injection and hyperperfusion from those of ischemia. The centers and borders of an ischemic area could be distinguished and the change with prolonged ischemia described. The relationship of these observations to the literature and pertinent studies of intracellular action potentials are discussed.

ISSN:0009-7330    

出版商:OVID    

年代:1960

数据来源: OVID

摘要:

Perfusion of the isolated rat's heart through certain types of polyvinyl chloride tubing results in a deterioration of cardiac performance. Since plastics are commonly used in heart-lung machines and transfusion-sets, this observation may be of some importance.

ISSN:0009-7330    

出版商:OVID    

年代:1960

数据来源: OVID

摘要:

A study was made of the changés produced in action potentials of frog ventricular cells by variation in ion concentrations, by administration of NaN3, 2:4 DNP, NaCN, NaIA and N2which shortened the potentials. The exposure of the perfused tissue to ionized acridines, barbiturates and desoxyglucose caused a prolongation of the action potentials. These actions as obtained were reversible. The evidence from the time-course and differential effects of inhibitors suggests that an active ion transport, modulated by KO+may be important in maintaining the plateau phase of the action potential.

ISSN:0009-7330    

出版商:OVID    

年代:1960

数据来源: OVID

摘要:

Resistance to blood flow through the small vessels of the dog foreleg decreased following local elevation of serum sodium and magnesium concentrations. Small vessel resistance increased following elevation of calcium concentration. Associated with the former changes was decreased responsiveness to levarterenol and methacholine. These changes likely result from effects of the cations upon the smooth muscle cell of the arteriole.

ISSN:0009-7330    

出版商:OVID    

年代:1960

数据来源: OVID

摘要:

The comparative potencies of uracil nnd thiouracil in terms of thyroidal changes, hypercholesteremia, azotemia, and incipient atherosclerosis were determined in rats fed cholesterol and cholic acid. Higher dietary levels of uracil were required to produce changes similar to those seen with thiouracil. Certain dietary components related to uracil were also studied. Orotic acid was found to have a dramatic effect on female rats: it favored a markedly lower serum cholesterol level and less cardiovascular sudanophilia. When orotic acid was combined with uracil, the uracil-induced hypercholesteremia and atherogenesis were significantly inhibited, particularly in the females. Orotic acid also protected against the uracil-induced thyroid hyperplasia in these females.

ISSN:0009-7330    

出版商:OVID    

年代:1960

数据来源: OVID

摘要:

The anabolic and weakly androgenie compound 19-norandrostenolone has been administered to cholesterol-fed cockerels in 2 dose levels. A marked fall in serum cholesterol occurred with the lower dose level and a significant reduction in the incidence of coronary artery lesion was noted with the higher dose level.

ISSN:0009-7330    

出版商:OVID    

年代:1960

数据来源: OVID

摘要:

The effects of altering the conductivities of the boundary media at the endocardial and epicardial surfaces of the ventricle on accession potentials in the ventricular wall and at its surfaces were studied in dogs. The amplitude of R at all points in the wall was decreased by any measure which increased the conductivity of the medium surrounding the heart or which decreased the conductivity of the medium in the ventricular cavity. The progression of R in the ventricular wall observed experimentally results, at least in part, from the differing conductivities of intracavitary blood, myocardium, and the medium surrounding the heart.

ISSN:0009-7330    

出版商:OVID    

年代:1960

数据来源: OVID