摘要:

Radioiodinated fatty acid bound to albumin (RIFA) was given by intravenous injection to dogs and moribund human subjects in order to label heart muscle.Photoscans of the thorax of dogs given RIFA revealed concentration of radioactivity in the ventricular region of the heart due to incorporation of the labeled fatty acid into myocardial triglyceride and phospholipid.Photoscans of the thorax following intravenous injection of radioiodinated serum albumin or NaI131showed a different density pattern in the region of the heart due to radioactivity in blood within the cardiac chambers.Areas of myocardial infarction were detected in photoscans of the thorax in 11 of 14 dogs in which one coronary artery was ligated. At necropsy the concentration of radioactivity was much higher in healthy myocardium than in infarcted muscle. The same distribution of radioactivity was observed in hearts from three human subjects with myocardial infarction given RIFA shortly before death. It is proposed that areas of myocardial infarction might be demonstrated during life by photoscans of the thorax following intravenous injection of RIFA.

ISSN:0009-7330    

出版商:OVID    

年代:1965

数据来源: OVID

摘要:

In order to evaluate the significance of an inductance in the condenser discharge circuit of defibrillators, additional experiments were performed by methods similar to those reported previously.1An inductance of 0.29 henry was connected in series with the condenser. It was shown that this modification results in a much higher threshold for arrhythmias than the threshold found earlier with pure condenser discharges. The differences were highly significant and show that functional damage to the heart, evaluated by the number and severity of arrhythmias produced, is less with an inductive resistance than without it. Inductive damping reduced the incidence of fibrillation by two-thirds. In 2160 damped discharges, ventricular fibrillation occurred only 36 times, all in the relative refractory period of the cardiac cycle. Fibrillation did not appear when the discharge was applied in the absolute refractory period or in the excitable period.

ISSN:0009-7330    

出版商:OVID    

年代:1965

数据来源: OVID

摘要:

Left coronary artery inflow was recorded in the dog heart-lung preparation by means of a Gregg cannula and a Shipley-Wilson recording rotameter. Reactive hyperemia (RH) was induced by 10-second occlusions. The excess blood flow after release was quantified by planimetry and related to the “blood flow debt” incurred during the period of occlusion. In the normothermic heart, the excess coronary flow was 431% of the flow debt. At heart temperatures of 30 and 25.6° C, it dropped to 228% and 143% respectively. There was shortening of the duration of reactive hyperemia and reduction of peak flow at lower temperatures. These results were discussed in the light of chemical theories of the mechanism of reactive hyperemia and the effect of hypothermia thereon.

ISSN:0009-7330    

出版商:OVID    

年代:1965

数据来源: OVID

摘要:

Cerebral blood flow was studied in 11 subjects using the krypton85method during a 10-minute saturation period followed by a 10-minute desaturation period. The calculated cerebral blood flow averaged 8.5% higher duringdesaturationthan duringsaturationfor the eight cases with blood flow values in the normal range. At higher flow (one case) the deviation was less pronounced, while at lower flows (two cases) the percentage difference increased. It is suggested that this systematic difference is due to the failure, at 10 minutes, of reaching equilibrium between average tissue and mixed venous blood in the human brain.The studies disclose a systematic error inherent in the Kety-Schmidt technique. According to observations in the literature this error is, however, not of such magnitude that it affects seriously the method as applied to the brain. Employing an inert gas saturation period of 10 minutes, an overestimation of the flow by about 10% probably occurs in normal subjects, while at subnormal flow levels the magnitude of this error increases somewhat. The error mentioned may be counteracted by prolonging the saturation period to 15 or 20 minutes and by extrapolation of the curves to infinity.

ISSN:0009-7330    

出版商:OVID    

年代:1965

数据来源: OVID

摘要:

Changes in pulmonary arteries and renal glomeruli were assessed in children born and resident at high altitude (Leadville, Colorado). The hypoxia appears to arrest normal neonatal decrease of pulmonary arterial smooth muscle in some of these children. No abnormalities were found in pulmonary veins or capillaries. A quantitative study also demonstrated enlargement of renal glomeruli in the hypoxic children after the first month of life, apparently due to a proliferation of normal glomerular elements.

ISSN:0009-7330    

出版商:OVID    

年代:1965

数据来源: OVID

摘要:

The concentrations of norepinephrine (NE), epinephrine (E) and dopamine (DA) were determined in dog hearts, each divided into a total of 18 parts. The concentration of NE was found to be significantly (three times) higher in the atria than in the ventricles while smaller differences existed within various subdivisions. In particular, the left atrial body had a lower concentration than other atrial tissue. The same was true of the left ventricular apex as compared to the base. No significant differences in NE were observed between the average concentrations in epicardial vs. endocardial layers of left ventricle, nor in the S-A or A-V node areas vs. surrounding tissues.The concentration of DA was also higher in atria than in ventricles. However there was no consistent correlation between NE and DA concentrations in the various atrial and ventricular parts. In the ventricles, DA was higher in left than in right ventricle and still higher in the A-V node region. In the atria DA was highest in the S-A node region and least in the atrial body. Both right and left atrial appendages contained high DA concentrations especially in their upper parts. In these parts and in the S-A node region the DA concentration was nearly equal to or slightly higher than that of NE. In most other areas DA was one-fifth to one-tenth the NE concentration.By contrast E was present in very low concentrations amounting on the average to less than 5% the amount of NE in the same tissue. No distinct pattern of E distribution in various parts of the heart could be established.It is concluded that no sample of the heart can be considered as representative of the entire organ, and that the catecholamine content of the entire heart cannot be taken as reflecting the concentrations in various specific areas.

ISSN:0009-7330    

出版商:OVID    

年代:1965

数据来源: OVID

摘要:

The relationships between the amplitude of the first heart sound and various hemodynamic parameters and their analog functions were systematically investigated in 51 dogs under morphine and pentobarbital anesthesia. Simultaneous hemodynamic and phonocardiographic tracings were obtained by cardiac catheterization, high speed recording, and analog computers. Changes in cardiodynamics were induced by:l-epinephrine, levarterenol, phenylephrine, isoproterenol, methoxamine, veratrine, vasopressin, histamine, atropine, saline infusion, mechanical obstruction of the aorta, pulmonary artery, or both venae cavae, embolization of the coronary arteries with plastic microspheres, mechanical rupture of aortic valve leaflets, or hemorrhage. In this way, the relationships were examined over a wide range of pressures, volumes, and cardiodynamics. The results showed that the amplitude of the first sound is not directly related to stroke output, P-R interval, heart rate, end diastolic, or systolic ventricular or aortic pressures. Only the peak rate of rise of left ventricular systolic pressure (first derivative maximum) had a consistent relationship to first sound amplitude. The right ventricle seems to contribute very little to the external first sound. These observations suggest that the amplitude of the first sound is related to left ventricular contractility.

ISSN:0009-7330    

出版商:OVID    

年代:1965

数据来源: OVID

摘要:

Results of this study show that 18 of 20 dogs survived prolonged periods of arterial hypotension when phenoxybenzamine was given to maintain adequate flow to the vital tissues of the body. This drug was used in order to block the catecholamine-induced arteriolar vasoconstriction and the histamine-induced venospasm. Reduction of peripheral resistance results in an increased perfusion of the capillary beds and a correction of O2and CO2tensions at the tissue level. One must emphasize the need for adequate fluid replacement, with this form of therapy; otherwise the marked vasodilation which occurs with phenoxybenzamine might result in an inadequate circulation, even as the resistance to flow in hypoxic tissues is eliminated.

ISSN:0009-7330    

出版商:OVID    

年代:1965

数据来源: OVID

摘要:

The oxidative capacity of the succinic oxidase and cytochrome oxidase systems, as measured by the oxidative response to succinate andp-phenylenediamine was studied in slices of aortas from rabbits and dogs subjected to an atherogenic regimen, and in the liver as reference tissue.In both animals, at an early stage in the atherosclerotic process, the oxidative capacity of both systems was increased in the atherosclerotic intima-media layer, separated at the cleavage plane, while at a later stage it was decreased.The intima-media of the uninvolved portions of the aorta showed a decrease in the oxidative capacity of the cytochrome oxidase system, whereas that of the succinic oxidase system remained unchanged.The liver, although the site of massive deposition of lipids, in the rabbit particularly, showed no enzymatic changes at any time during the administration of the atherogenic regimen.These findings indicate that metabolic alterations of the arterial wall are associated with the development of atherosclerosis.

ISSN:0009-7330    

出版商:OVID    

年代:1965

数据来源: OVID

摘要:

Cardiac myosin was obtained from the hearts of normal dogs by conventional extraction and precipitation techniques, followed by ammonium sulfate fractionation in the presence of 2.0 M lithium chloride. The molecular characteristics of this protein preparation are presented. Cardiac myosin prepared by this technique shows less tendency than conventionally prepared solutions to denature when stored at 0 to 4°C, and has a significantly higher ATPase activity. Comparison of canine cardiac myosin and skeletal muscle myosin, obtained under identical conditions, revealed no differences between these two proteins in their intrinsic viscosities, S20. w, molecular weight, and UV absorbances, although ATPase activity was lower for cardiac myosin.

ISSN:0009-7330    

出版商:OVID    

年代:1965

数据来源: OVID