bluuebunny/crossref_metadata_2025_split huggingface dataset:
Experimental Pulmonary Arterial Hypertension in the Newborn Calf
Authors: Vogel John H. K. , Averill Keith H. , Pool Peter E. , Blount S. Gilbert 
Published: June 2012

1. The left pulmonary artery was ligated in day-old calves. All animals developed pulmonary arterial hypertension with resting
mean
pressures as high as 114 mm Hg. This was associated with a reduction in the pulmonary arterial vascular bed of the right lung and right ventricular hypertrophy. The longest survival has been five months; death being associated with congestive heart failure.

2. Pulmonary hypertension developed without concomitant rise of pulmonary arterial wedge pressure.

3. Inhalation of 13% O
2
caused an average rise of 45 mm Hg in mean pulmonary arterial pressure, as compared with 21 mm Hg in normal calves and nine in yearling steers.

4. Inhalation of 41% or 100% O
2
caused an average decrease of 29 mm Hg in pulmonary arterial pressure, as compared with 14 mm Hg in normal calves.

5. Acetylcholine reduced the elevated pulmonary arterial pressure suggesting that vaso-constriction played an important role in the development of the pulmonary hypertension. Tolazoline was ineffective.
6. The spectrum of reactivity of the pulmonary vascular bed among species as well as within a given species is illustrated.
Effects of Alterations in Aortic Impedance on the Performance of the Ventricles
Authors: WILCKEN DAVID E. L. , CHARLIER ANDRÉ A. , HOFFMAN JULIEN I. E. , GUZ ABRAHAM 
Published: June 2012

We have investigated the effects of sudden changes in the load against which the left ventricle contracts in healthy conscious dogs. During a steady state, initial responses were assessed by comparing the beat before with the beat after such a change. Flow was measured by electromagnetic flowmeters and pressure usually by a catheter-tip transducer.
Results show that under the conditions of these experiments the curves relating external work and power to load are consistent with the parabolic relationship shown for isolated hearts and muscle strips and that in each case the left ventricle normally functions near the peak of the curve.
When an increased load was maintained until a new steady state was reached the left ventricle still functioned on the descending limbs of what presumably were different work-load and power-load curves. It was concluded from this that either the increase in load was too great or the time too short for reflex humoral and intrinsic mechanisms to readjust and permit the ventricle to function again at the peak of each curve, or that the circulatory system does not make relatively rapid adaptations in this way to an increase in systemic load.
The immediate effects of changes in load on left ventricular stroke volume were similar to those seen in isolated preparations. Stroke volume varied inversely with the load. Stroke volume changes were accompanied by changes in the duration, rate, and velocity of ejection. The duration of the isovolumetric phase was affected little but the period from valve closure to the end of ventricular relaxation varied with the load so that the total duration of contraction and relaxation of the ventricle was relatively unchanged, though an increase in load did tend to prolong it.
Before the onset of the baroreceptor response the right ventricle was not affected, the two ventricles acting independently in relation to all these changes.
Effect of Carotid Baroceptor Stimulation upon the Forelimb Vascular Bed of the Dog
Authors: ZINGHER DIANA , GRODINS FRED S. 
Published: June 2012

The response of the musculocutaneous vascular bed of the dog's forelimb to carotid baroceptor stimulation was determined by measuring pressures at the level of the large artery, small artery, small vein, and large vein along with limb blood flow. In one series, limb blood flow was uncontrolled. In two other series, the limb was perfused at a constant flow rate and was also isolated from collateral flow in one of these.
Elevation of carotid sinus pressure in the constant flow isolated (CFI) series produced an average fall in total limb, small vessel, and venous segment resistance of 27%, 36%, and 22% respectively but no significant change in arterial segment resistance. Since transmural pressure fell significantly in all three segments, active vasodilatation must also have occurred in all, including the arterial. This is reflected in the significant increase in compliance calculated for both the lumped arterial and lumped venous segments. In any given animal, there was a positive correlation between the percentage reduction in systemic pressure and total limb resistance, but this correlation was not evident between animals.
In the series in which limb blood flow was uncontrolled, flow decreased consistently and significantly when carotid sinus pressure was elevated, the average decrease being 30%. Despite possible confusion introduced by the presence of an added fixed resistance in the limb circuit (rotameter), it is probable that this finding faithfully reflects the behavior of the intact limb.
Intramural Myocardial Shear During the Cardiac Cycle
Authors: FEIGL ERIC O. , FRY DONALD L. 
Published: June 2012

Instantaneous and continuous shearing strains at various sites in the wall of the left ventricle were measured in 19 dogs with a specially designed transducer. Relatively large shearing strains occurred during the "isovolumic" and immediately prediastolic portions of systole. Shearing strain during diastole was small. Under control conditions the average shearing strain during the ejection period of systole was 0.0218 radians (1.25°) at a 6 mm depth into the myocardium. Intravenous infusion of norepinephrine (approximately 0.001 mg/kg per minute) increased myocardial shear from 0.0177 radians (1.01°) to 0.0274 radians (1.57°) during the ejection period.
It is concluded that shearing strain in the myocardium during the ejection period is relatively small.
Measurement of Myocardial Blood Flow in Animals and Man by Selective Injection of Radioactive Inert Gas into the Coronary Arteries
Authors: ROSS RICHARD S. , UEDA KEIJI , LICHTLEN PAUL R. , REES J. RUSSELL , Redden Redden , Kaelber Christa 
Published: June 2012

1. Human myocardial blood flow has been measured by the determination of precordial radioactivity after the injection of solutions of radioactive gas directly into the coronary arteries following coronary arteriography.
2. The accuracy of radioactive gas measurements has been established in dog experiments by comparison with coronary blood flow simultaneously measured by rotameter.
3. This method has two major advantages over the existing methods of measuring human myocardial blood flow. Firstly, the right and left coronary circulations can be studied separately, this being the only method whereby the right circulation can be studied in man. Secondly, anatomical and physiological correlations are readily available as arteriography is an essential feature of the method.
Chronotropic Effects of Norepinephrine and Tyramine: A System Response Analysis
Authors: BATTERSBY EDWARD J. , NEWMAN ELLIOT V. 
Published: June 2012

An analog simulation of the chronotropic effects of norepinephrine and tyramine in the canine heart-lung preparation is presented. The temporal aspects of those responses are described in quantitative terms.
Reserpine produced deprivation suprasensitivity to norepinephrine may be considered as a corollary of the system response nonlinearity to that drug.
Discrepancies between tyramine rate responses and the relatively small amounts of norepinephrine released are resolved by the assumption that the receptor space for norepinephrine has a capacitative function and is not in free dilutional equilibrium with the perfusing blood. This mechanism would allow for a unitary explanation of tyramine action based upon competition with norepinephrine for available storage sites.
Comparison of Dilution Technics Using Aortic Injection with Upstream Sampling for Assessment of Aortic Regurgitation
Authors: ARMELIN EGAS , DONALD DAVID E. , WOOD EARL H. 
Published: June 2012

The distances between the aortic valve and sites in the aorta from which no retrograde flow of injected indicator could be detected in the left ventricle were determined, without thoracotomy, in two normal dogs and in ten dogs with chronic experimental aortic regurgitation. It was found that these distances attained maximal values when the aortic injections were timed to occur just at the end of systole or onset of diastole.
Distances downstream from the origin of the left subclavian artery from which no retrograde flow occurred to this vessel were determined similarly in these same animals and, in confirmation of Warner and Toronto, similar relationships to the timing of the injections were obtained. These distances down the aorta, designated as "disappearance distances", were converted to "disappearance volumes" by measuring the diameters of the silhouette of successive aortic segments from aortograms made after contrast medium was injected into the left ventricle of these animals.
The regurgitant flow through the aortic valve per heartbeat was estimated on the basis of the amount of immediately appearing indicator detected in the left ventricle following injection of indicator approximately 1 cm downstream from the aortic valve. Correlation coefficients of 0.88 and 0.77 were obtained between these stroke-regurgitation values and the disappearance volumes from the aortic valve and subclavian artery, respectively. The standard errors of the estimate of the regurgitant flow per beat from these regression equations were ± 2.7 and ± 2.9 ml/beat, respectively. The correlation coefficients between stroke-regurgitation values and the disappearance distances from the valve and subclavian artery were 0.83 and 0.81, respectively, and the respective standard errors of the estimate of stroke regurgitation from these regression equations were ± 3.2 and ± 3.3 ml/beat.
It is concluded that determination of the maximal distances downstream in the aorta of sites from which retrograde flow of injected indicator can be detected in the left ventricle or subclavian artery is a valid method for estimating the severity of experimental aortic regurgitation in dogs. Since determinations of the disappearance distance from the aortic valve can be carried out readily in conjunction with measurement of the left ventricular regurgitation fraction, it is suggested that advantage be taken of the increase in reliability which accrues from the combined use of these two independent methods for the estimation of the degree of aortic regurgitation.
Abnormal Indicator Dilution Patterns in Dogs Produced by Flowmeter Probes on the Pulmonary Artery
Authors: FOX IRWIN J. , CASTANEDA ALDO R. , WEBER KENNETH C. 
Published: June 2012

In acute experiments on open chested dogs, indicator dilution curves were recorded before and after placing electromagnetic flow probes on the pulmonary artery. The flow probes caused severe abnormalities in the dilution curves. The abnormalities resembled those seen in cases with left-to-right shunts.
The following facts suggest that the abnormalities are caused by turbulence and eddy formation near the flowmeter probe: (a) Direct measurements with a fiberoptic densitometer showed that clearance of dye just proximal to the probe was delayed. (b) The abnormalities disappeared immediately after removal of the probe or when the dye was injected just downstream to the probe. (c) The areas under curves recorded from the pulmonary artery upstream from the probe were greater than the areas under curves recorded at this same site without the probe.
Cardiac output and systemic arterial pressure were lower in animals with abnormal dilution curves than in those with normal femoral curves.
Effect of Coronary Vasodilator Drugs on Retrograde Flow in Areas of Chronic Myocardial Ischemia
Authors: FAM WADIE M. , MCGREGOR MAURICE 
Published: June 2012

The effects of two coronary vasodilator drugs, nitroglycerin and dipyridamole, on the coronary collateral flow were studied in twelve dogs with chronic myocardial ischemia and in five normal dogs, by means of the retrograde flow technique.
In the ischemic dogs with well developed collateral circulation, both drugs caused a reduction in systemic blood pressure. Dipyridamole caused a significant reduction in both the retrograde flow and peripheral coronary pressure as well. Nitroglycerin, by contrast, did not cause a significant reduction in either retrograde flow or peripheral coronary pressure in spite of a greater fall in mean arterial pressure. When arterial pressure was held constant artificially, nitroglycerin caused a large increase of retrograde flow in chronic "ischemic" dogs while dipyridamole did not.
In normal dogs these differences between the two drugs were not observed. Both drugs caused a reduction of retrograde flow and peripheral coronary pressure which paralleled the reduction in systemic pressure.
In both ischemic and normal dogs, dipyridamole caused a reduction in the coronary arteriovenous oxygen difference. Nitroglycerin did not change this value.
Reported differences between these two drugs, together with these observations, suggest that nitroglycerin may have an action which is to be seen only in the presence of well developed collateral circulation; this is to increase flow through collateral channels without significantly altering total coronary artery flow. Dipyridamole does not seem to alter collateral flow but does increase total coronary flow. The site of action of these two drugs in the coronary vascular tree must thus be different.
Incorporation of Sulfate-S
35
and Glucosamine-1-C
14
into Heparin During Perfusion of Isolated Rat Liver
Authors: FERRANTE NICOLA Di , MEYERS ANN L. , MILLER LEON L. 
Published: June 2012

Sulfate-S
35
and glucosamine-1-C
14
are incorporated into heparin which has been added to the blood perfusing an isolated, surviving rat liver. Although both labels are firmly bound to heparin, such uptake does not necessarily indicate synthesis of the polymer.

Despite the fact that the perfused heparin has undergone some moderate depolymerization, its biological activity remains unchanged.
The presence in the bile of material containing hexuronic acid and hexosamine but deprived of anticoagulant activity suggests that products derived from heparin breakdown may be eliminated in the bile.
Regional Distribution of Catecholamines in the Dog Heart
Authors: ANGELAKOS EVANGELOS T. , Millard Ronald W. 
Published: June 2012

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.
Electrocardiographic Studies in Homologous Canine Heart Transplantations
Authors: DEPASQUALE NICHOLAS P. , BURCH GEORGE E. , PENA EDGAR , REEMTSMA KEITH 
Published: June 2012

1) In a series of ten dogs subjected to heart transplantation, serial electrocardiograms were recorded from the transplanted and the recipient hearts.
2) Approximately one week following transplantation, changes appeared in the S-T segment and the T wave of the electrocardiogram of the recipient heart without significant alteration of the QRS complexes. These findings resembled those associated with myocarditis and/or pericarditis.
3) Electrocardiographic changes did not appear in animals treated with drugs alone or in animals subjected to kidney transplantation. These findings suggest the possibility of release from transplanted hearts of an organ-specific substance or substances which affected the hearts of the recipients.
Effects of Acetylstrophanthidin on Coronary Vascular Resistance and Myocardial Oxygen Consumption
Authors: WALDHAUSEN JOHN A. , KILMAN JAMES W. , HERENDEEN THOMAS L. , ABEL FRANCIS L. 
Published: June 2012

The effects of acetylstrophanthidin on coronary circulation were studied in 31 dogs. Coronary blood flow was measured in empty beating hearts or in fibrillating hearts by collecting coronary venous return during perfusion of the systemic circulation (cardiopul-monary bypass). In 14 animals with ventricular fibrillation, acetylstrophanthidin caused an initial coronary constriction and fall in coronary blood flow. This was followed, after approximately 10 minutes, by a significant drop in resistance and a rise in coronary blood flow which persisted for the remainder of the experiment. Associated with the increase of blood flow was an increase of myocardial oxygen consumption. This effect was not abolished by ganglionic blockade, cardiac denervation or bilateral adrenalectomy.
In nine dogs with beating but empty hearts, after the initial constriction of the coronary vessels, there was only a small change in coronary blood flow and resistance, although myocardial oxygen consumption was increased. The lack of coronary vasodilatation was attributed to increased mechanical resistance due to the augmented force of contraction produced by the drug.
Lipolytic Activity of Post-Heparin Plasma in Hyperlipemia and Hypolipemia
Authors: KUO PETER T. , BASSETT DAVID R. , DIGEORGE ANGELO M. , CARPENTER GARY G. 
Published: June 2012

(1) The role of post-heparin plasma lipolytic activity (PPLA) in the production of hyperglyceridemia was investigated in patients with high concentrations of plasma triglycerides produced in two ways, viz. fat-induced and "mixed" (both fat and carbohydrate-induced). While on a self-chosen diet, the PPLA levels of patients with "mixed" type of hyperglyceridemia differed little from those of young healthy subjects. PPLA levels of these patients were promptly lowered by rice diet, despite the persistence of hyperglyceridemia. Normal serum lipid concentrations and low PPLA levels were induced and maintained in these patients by reducing moderately their intake of both dietary fat and calories.
(2) PPLA levels were reduced in the fat-induced hyperglyceridemic patients both before and after the use of low fat diet to reduce their plasma triglyceride concentrations.
(3) PPLA was also low in patients with low and absent beta-lipoproteins, and in those with disturbance of intestinal fat digestion and absorption.
Differences in Cardiac Hypertrophy in Exercise and in Hypoxia
Authors: VAN LIERE EDWARD J. , KRAMES BARBARA BAUGH , NORTHUP DAVID W. 
Published: June 2012

A group of rats, including both sexes, was exercised on an electrically-driven treadmill at the rate of one mile per hour for two hours daily to a total of 60 hours. Another group, also including both sexes, was exposed to intermittent hypoxia for eight hours daily, six days per week, for four weeks at a barometric pressure of 303 mm Hg corresponding to a simulated altitude of approximately 24,000 feet (7,315 m). All these animals showed significant hypertrophy of both ventricles.
Exercise produced about the same percentage of weight increase in the right and also in the left ventricular walls. The per cent increase of the right ventricular wall relative to that of the left ventricular wall was greater after intermittent hypoxia than after exercise. The ratio of left ventricular weight/right ventricular weight was significantly less in the hypoxic group than in the exercised group. This indicates a relative right ventricular hypertrophy produced by the intermittent hypoxia. Reasons are given to indicate that the pulmonary hypertension associated with hypoxia is the cause of this right ventricular predominance.
Analysis of Ventricular Dimension in the Unanesthetized Dog
Authors: NINOMIYA ISHIO , WILSON MICHAEL F. , Gibson John M. , Segnitz Richard H. 
Published: June 2012

Left ventricular dynamics was studied in the unanesthetized dog by an analysis of simultaneous recordings of left ventricular transverse dimension, pressure, and ascending aortic flow in 16 experiments while the dogs were reclining, standing, and during graded treadmill exercise. Statistical analysis of the dimension data revealed typical patterns of isovolumetric changes which suggest asynchronous contraction and relaxation. The fact that maximum and minimum dimension levels did not coincide with levels at onset and end of ejection led to the concept of the "effective" stroke shortening in the left ventricular transverse dimension.
An ellipsoid of revolution was the best approximation of left ventricular shape while reclining and standing, but during exercise the shape constant decreased toward a paraboloid of revolution. Analysis of the data from correlation coefficients and by using the principle of the compression ratio, which is independent of shape, indicated that stroke shortening and stroke volume may be a function of initial length or volume for the resting states but that during exercise their increase was due primarily to extrinsic influences which acted to change the magnitude of the contractile response.
Spread of Excitation from the Sinus Node
Authors: SANO TOYOMI , YAMAGISHI SHUNICHI 
Published: June 2012

Microelectrodes were employed to determine the mode of propagation of excitation from the sinus node in the rabbit heart. The excitation starts from the sinus node radially, at first, but then proceeds to the crista terminalis, often obliquely. This is because some special tissue having a slow conduction velocity lies behind the sinus node, and also because there is a zone of relatively faster conduction at the basal wall of the superior vena cava. Once the excitation wave enters the crista terminalis, it travels rapidly in two opposite directions through two branches of the ring-like structure which is formed by the crista terminalis and its extension. The excitation wave traveling through the branch encircling the inferior vena cava reached the atrioventricular node earlier in most instances.
In the caval region inside the ring-like structure there is a zone of relatively faster conduction. The conduction to the atrioventricular node through this route is latent in the normal state, because conduction through the ring-like structure takes place beforehand.
In the caval region near the sinus node, the conduction velocity of the excitation wave from the spontaneously beating sinus node was greater than that from the electrically driven atrium. The spontaneous action potential showed also a steeper rise than that produced by electrical stimulation. The mechanism responsible for this is discussed.