bluuebunny/crossref_metadata_2025_split huggingface dataset:
Pulsatile Pressure and Flow Through Distensible Vessels
Authors: STREETER VICTOR L. , KEITZER W. FORD , BOHR DAVID F. 
Published: June 2012

The basic differential equations for elastic wall material and for continuity and momentum are derived, including fluid frictional resistance of the wall of the tubes, based on one-dimensional flow. These partial differential equations are transformed into four ordinary differential equations using the theory of characteristics. Then difference equations are developed and by an interpolation method (method of specified time intervals) equations are obtained for computation of velocity and pressure at equally-spaced sections along the vessel at specified equal time intervals. The equations are first applied to a flexible tube of initial constant diameter, with a pulse flow taken from in vivo experiments.
Equations are then developed for tapering tubes with distributed outflow along their lengths (to simulate branches). Pressure-time data from femoral artery measurements are then used to compute flow through the artery, and the results are compared with electromagnetic flowmeter data. Computed flow is greater than measured flow if a friction factor for laminar flow is used. Frictional losses of energy in the normal pulsatile flow in the femoral artery are similar to those of turbulent flow.
Induced Changes in the Pattern of Pulmonary Blood Flow in the Rabbit
Authors: Lehr David E. , Tuller Martin A. , Fisher Lloyd C. , Ellis Kent , Fishman Alfred P. 
Published: June 2012

1. In the normal, unanesthetized rabbit, resting quietly in its normal position, catheterization of the right ventricle (and central veins) altered the distribution of blood throughout the lung in a characteristic manner.
2. Regional pulmonary vasoconstriction, rather than passive changes in vascular caliber or in the flow properties of blood, seemed to be involved.
3. The mechanism for the regional pulmonary vasoconstriction is considered in terms of a neurohumoral pathway, involving afferent pathways from the right heart, connecting channels in the upper cervical segments of the spinal cord, and release of a histamine-like substance at the neuro-vascular junctions.
Actin from Heart Muscle: Isolation, Purification, and Physicochemical Properties
Authors: KATZ ARNOLD M. , HALL ELIZABETH J. 
Published: June 2012

A systematic study of the preparation of actin from cardiac muscle has led to the use of a modification of Straub's original technique which gave good yields of an F-actin with very high polymerizing activity. The G-actin obtained by this method was found to be homogneous in starch gel electrophoresis; the sedimentation behavior suggested that small amounts of oligomers of G-actin may have been present in addition to monomeric G-actin, but there was no evidence of impurity.
The partial specific volume of dog cardiac actin was approximately 0.715 ml/g, the sedimentation coefficient extrapolated to infinite dilution of the protein was 3.44 S, and the intrinsic viscosity was 0.16 dl/g. Precise measurement of the diffusion coefficient was not feasible due to the instability of the G-actin monomers in solutions of high ionic strength. The sedimentation behavior of rabbit cardiac actin was similar to that of dog cardiac actin.
The molecular weight of dog cardiac actin, estimated from sedimentation and viscosity data, was 62, 300. Since this estimate of molecular weight is similar to published values for rabbit skeletal actin, the different properties of cardiac and skeletal muscle cannot be attributed to a major physicochemical difference between the actins of these two tissues.
Effect of Experimental Congestive Heart Failure and Acetyl Strophanthidin on Myocardial Electrolyte and Water Content
Authors: BLISS HARRY A. , ADOLPH ROBERT J. 
Published: June 2012

The syndrome of chronic congestive heart failure was produced in female dogs by progressive pulmonary artery constriction. A factorial experimental design, containing seven experiments of four dogs each, was employed. Each experiment was completed in one day and consisted of two groups of two dogs each, one group containing dogs with heart failure and the other, normal dogs. One animal from each group received intravenous acetyl strophanthidin, 0.015 mg/kg ascites-free weight, while the other was given an injection of inert material. The heart was quickly removed from the chest nine minutes after the injection and the right ventricle was taken for analysis. Previous work indicated that this dose of the drug produced and inotropic effect both in normal animals and in dogs with heart failure without producing digitalis toxicity.
The myocardium from animals with congestive heart failure contained significantly less potassium but more sodium, chloride, and water per kilogram of dry fat-free blood-free myocardium than the myocardium from normal dogs. The concentration of sodium plus potassium in tissue water was subnormal in failing hearts. The sodium and chloride composition of the fluid gained by failing hearts differed significantly from that of interstitial fluid.
Acetyl strophanthidin increased myocardial chloride and water. Although potassium in the myocardium was unchanged in treated control dogs, it increased significantly after acetyl strophanthidin in animals with heart failure.
The findings are consistent with myocardial cellular swelling in congestive heart failure. The quantity of blood in each kilogram of failing myocardial tissue was severely reduced, probably because of muscle fiber hypertrophy. The possibility is considered that this alteration, together with the increased tissue water, may lead to lowered oxygen tension in failing heart muscle.
It is suggested that digitalis exerts two opposing effects on ion transport through the myocardial cell membrane and that neither of these is fundamental to its inotropic action.
Group Isolation and Atherosclerosis in Cholesterol-Fed Cockerels
Authors: PICK RUTH , KATZ LOUIS N. , CENTURY DOLORES , Johnson Philip J. 
Published: June 2012

Group isolation, a highly unnatural environmental situation in cockerels, increases atherogenesis and decreases regression of previously induced atherosclerosis. This alteration occurs despite the absence of change in the hypercholesterolemic response to the diet in the induction experiments. It is accompanied by a reduction in weight gain despite food intake similar to the controls.
Disturbing the social order by altering the pecking order in flocks of cockerels on a cholesterol-oil containing diet does not alter hypercholesterolemia and atherogenesis. However, it leads to increase in sex characteristics. Physical activity, with or without alterations in pecking order, causes a reduced weight gain even when food intakes are not altered.
It is concluded that environmental factors can and do influence atherosclerosis. The types of environmental change which can produce this effect and the exact mechanisms involved require further study.
Pressure Transients Occurring in Diastole in the Central Aorta
Authors: Piemme Thomas E. , Dexter Lewis 
Published: June 2012

From the observations noted and from physical considerations, the following may be concluded:
Cardiac events of sufficient energy content to cause sudden displacement of the heart and great vessels give rise to pressure transients that may be seen in all chambers if carefully looked for. These are, in reality, "acceleration" waves superimposed upon otherwise smooth pressure functions.
Such an oscillation occurs normally at the time of isometric ventricular contraction. The energy content of isometric ventricular contraction results in an induced pressure wave in all chambers, but is most prominently seen in the low pressure atria as the "c wave, " and in the aorta and pulmonary artery as small, relatively high frequency, presystolic impulses. The event is obscured in the ventricles by the rapidly rising intraventricular pressure but may be identified when the ventricular pressure is differentiated.
Under pathological circumstances, atrial contraction and early ventricular filling may result in peripherally recordable pressure deflections.
Production of Hypertension and Vascular Disease by Kidney Extracts
Authors: MASSON GEORGES M. C. , KASHII CHUJIRO , PANISSET JEAN-CLAUDE , YOGI SHIGERU , PAGE IRVINE H. 
Published: June 2012

Hypertension was induced in rats by constricting the aorta between the origins of the renal arteries. The left kidney, which became ischemic and atrophic ("endocrine kidney"), caused a malignant type of hypertension associated with weight loss, cardiac hypertrophy, hypertension, cardiac necrosis, nephrosclerosis of the right kidney, and arteritis. Amounts of pressor substances were increased in the left kidney and decreased in the right as compared with those in kidneys of normal rats.
Aqueous extracts of ischemic kidneys, of kidneys contralateral to ischemic kidneys and of normal kidneys were prepared and the supernatant solutions were injected subcutaneously into test rats which had been uninephrectomized a few hours previously. Extracts of ischemic kidneys caused hypertension, cardiac hypertrophy, weight loss, and renal and vascular lesions mimicking the signs which result from renal ischemia. The extracts from the other kidneys were inactive. Administration of renin in doses roughly equivalent in pressor activity to the extracts of ischemic kidneys caused a rise in pressure, diuresis, and proteinuria but no lesions when given subcutaneously.
It is proposed as a working hypothesis that renal hypertensive disease results not only from increased secretion of renin and formation of angiotensin but from simultaneous release from kidneys with reduced perfusion pressure of a substance which augments the enzymatic formation of angiotensin. This substance is presumably absent from normal kidneys and from semipurified renin preparations.
Coronary Circulation and the Tail of First-Pass Indicator Dilution Curves
Authors: CROWDER BENNETT L. , GREER WILLIAM C. , SHEPPARD CHARLES W. 
Published: June 2012

In a series of canine heart-lung preparations, single-pass indicator dilution curves were obtained with and without cannulation of the coronary sinus. Further evidence was obtained that the tails of the curves are significantly elevated above the tails predicted from the simple one-dimensional random-walk relation.
To provide estimates of the contributions which dye circulating through the coronaries might make to the tails, curves were obtained in the same preparation with and without cannulation, and at high and low mean arterial pressure. A method was developed for cannulation which permitted sampling through an exterior low-resistance cannula system which was secured in the coronary sinus without producing serious obstruction of the coronary sinus tributaries or interference with the conduction system.
Although the classical exponential down-slope gave better agreement than the random-walk relation, the experimental curves were frequently elevated and prolonged when compared to the exponential curve. The difference in area amounted to approximately 4.5%. In experiments at high mean arterial pressure without bypass of coronary dye the tail was significantly higher on the average by 3% compared to the tail in the same preparation with bypass at low pressure. Estimating that 60 to 70% of coronary dye would be successfully bypassed, the total coronary contribution to the tail of 4 to 5% of dye on the average is not sufficient to account for the excess of experimental tails over random-walk curves.
Functional Cardiac Deterioration During Development of Hemorrhagic Circulatory Deficiency
Authors: GOMEZ OSCAR A. , HAMILTON WILLIAM F. 
Published: June 2012

A massive infusion test has been devised to evaluate the functional capacity of the heart.
In five dogs extensive surgical procedures followed by episodes of arterial hypotension at 30 mm Hg and lasting 90 minutes caused severe cardiac incapacity, which was demonstrated by failure of rate of cardiac work to increase throughout the infusion together with a large rise in left atrial pressure. This incapacity was not evident in tests made immediately after the hypotensive episode. The damage became more and more severe in tests performed 90 and 150 minutes after the end of the hypotension even though mean arterial pressure was maintained at 100 mm Hg. Operated control dogs did not show cardiac deterioration in tests timed as above. The rate of cardiac work continued to increase throughout the infusion with a relatively small rise of left atrial pressure.
In a series of five dogs, flow to the coronary arteries and to those supplying the head and forelimbs was maintained by normal blood pressure while the rest of the animal was made hypotensive for 90 minutes. The arterial pressure in the whole animal was then returned to an average level of 100 mm Hg. Tests made at intervals after the hypotension showed equivocal evidence of cardiac deterioration.
In another series of four dogs, prepared as above, the partial hypotension lasted 150 minutes before the arterial pressure was returned to normal. Tests at intervals after hypotension showed cardiac damage in all the animals and severe damage in three. Evidence is presented indicating that the peripheral vascular bed had deteriorated functionally as a result of 150 minutes of partial hypotension.
Systemic Blood Pressure Response to Changes in Right Ventricular Function
Authors: PINKERSON ALAN L. , KOT PETER A. 
Published: June 2012

The relationship between right ventricular and aortic pressure was studied in open-chest anesthetized dogs. A simultaneous increase in both pressures was observed in animals with an intact circulation and animals with the systemic circulation perfused at a constant rate and stroke volume by an extracorporeal pump. With gradual partial constriction of the main pulmonary artery, the increase in right ventricular systolic and aortic pressures occurred without consistent change in other measured parameters. Bilateral cervical vagotomy abolished the systemic vascular response.
These observations are consistent with a pressor reflex which is mediated over vagal afferent fibers from the right ventricle. It is suggested that in animals under varying physiologic stimuli an increase in right ventricular pressure is associated with a reflex increase in systemic vascular resistance. In abnormal circumstances with increased resistance to right ventricular emptying, the increased total peripheral vascular resistance would be important in maintaining systemic blood pressure and blood flow.
Peripheral Vasodilator Action of Eledoisin, Bradykinin, and Nitroglycerin in Anesthetized Dogs
Authors: BERGAMASCHI MARIO , GLÄSSER ALFREDO H. 
Published: June 2012

The peripheral vasodilator action of the endecapeptide eledoisin in the anesthetized dog has been described in this paper.

Blood flow through the vascular beds supplied by the femoral artery increased following doses of eledoisin as low as 0.5 nanogram/kg (4.25·10
-13
mole/kg) injected intravenously, and 0.001 ng/kg (8.5·10
-16
mole/kg) injected intra-arterially. The blood vessels of the skin were less reactive than blood vessels in muscle.

Eledoisin exerted a powerful vasodilator effect on vascular beds supplied by the common carotid, the external and internal carotid, the occipital and the vertebral arteries.
Renal and mesenteric vascular beds did not respond significantly to eledoisin.
Comparison with some other vasodilator drugs was made. Following intra-arterial doses which do not affect systemic blood pressure, eledoisin was 5 to 50 times more active than bradykinin on total femoral and muscle flows; both showed the same activity on skin flow. Nitroglycerin, carbaminoylcholine, and papaverine were even less active than bradykinin.
Water and Electrolyte Content of Normal and Hypertensive Arteries in Dogs
Authors: JONES ALLAN W. , FEIGL ERIC O. , PETERSON LYSLE H. 
Published: June 2012

This study was designed to establish values for the water and electrolyte content along the arterial tree in the dog under normal conditions and to determine how the normal electrolyte pattern was altered in renal hypertension.
Determinations of vessel wall water, potassium, sodium, and chloride contents have shown that the water and electrolyte contents from the various sites along the arterial tree differ significantly from each other. Total water and potassium contents decrease progressively from the ascending aorta to the femoral and carotid sites, while the sodium and chloride contents showed the opposite trend. These differences were significant statistically. These trends may not persist along the entire vascular tree to very small arteries, as indicated by analysis of mesenteric arterial samples. Studies of vessel wall inulin space supported the view that these differences result from the relative distribution of cellular and noncellular material; thus the proximal aorta contains a relatively greater proportion of cellular (smooth muscle) material than more distal sites such as the femoral and carotid arteries. A review of the literature further supports these findings.
In experimentally induced renal hypertension the same trends persist along the aorta, but the total water and sodium contents are significantly elevated at all sites.
Characteristics of Reactive Hyperemia in the Canine Intestine
Authors: SELKURT EWALD E. , ROTHE CARL F. , RICHARDSON DANIEL 
Published: June 2012

The isolated ileum of the dog shows a characteristic hyperemia following brief periods of arterial occlusion. The magnitude of this reactive hyperemia depends more upon prolongation of flow related to duration of ischemia, than upon increases of maximal or peak blood flow. Repayment of flow deficit, by the added flow of reactive hyperemia, averaged only 35% in the intestine, far below that found by others in skeletal muscle and in the coronary circulation. Nevertheless, estimates of oxygen debt indicated that this debt was overpaid, even after five minutes of ischemia.
A small but consistent increase in weight of the isolated segment was observed during the postocclusion phase. It was found that this weight increase was due largely to increase of the volume of blood in the ileum. The peak of the volume increment appeared slightly later than the peak of flow increase, and for this reason was ascribed to increase in volume of the capacity vessels.
In an attempt to assess the respective roles of myogenic vs. metabolic mechanisms in causation of reactive hyperemia, arterial pressure was restored during occlusion by injecting dextran solution into the arterial segment. Pressures in excess of control values did not abolish the hyperemic response. It was concluded that the reactive hyperemia observed in the ileum was chiefly metabolic in origin.
Oxidative Capacity of Atherosclerotic Tissue of Rabbit and Dog, With Special Reference to Succinic Dehydrogenase and Cytochrome Oxidase
Authors: MAIER NELICIA , HAIMOVICI HENRY 
Published: June 2012

The oxidative capacity of the succinic oxidase and cytochrome oxidase systems, as measured by the oxidative response to succinate and
p
-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.
Comparative Cardiovascular Effects of Tyramine, Ephedrine, and Norepinephrine in Man
Authors: COHN JAY N. 
Published: June 2012

The systemic hemodynamic and forearm vascular effects of tyramine, ephedrine, and norepinephrine were studied in normal male subjects. The pressor effect of tyramine was associated usually with bradycardia, unchanged cardiac output, and moderate arteriolar constriction in the forearm. A similar pressor effect of ephedrine was characterized by an increase of heart rate and output, with a slight fall in forearm vascular resistance. Occasional subjects responded to tyramine with an increase of cardiac output and a fall in forearm vascular resistance, and to ephedrine, with a marked increase of vascular resistance. The pressor effect of norepinephrine was associated always with bradycardia and with marked arteriolar and venous constriction in the forearm.
Brachial arterial infusions of the drugs in nonpressor doses confirmed the vascular effects. Norepinephrine produced dose-dependent forearm constriction in all subjects, while vasodilatation was observed occasionally with tyramine and frequently with ephedrine.
The demonstrated differences in local vascular and systemic hemodynamic effects of these drugs suggest some inconsistency in the hypothesis that the effect of either ephedrine or tyramine is mediated exclusively by norepinephrine release.
Aberrant A-V Impulse Propagation in the Dog Heart: A Study of Functional Bundle Branch Block
Authors: MOE GORDON K. , MENDEZ CARLOS , HAN JAOK 
Published: June 2012

Excessive delay and configurational change of ventricular responses to atrial premature beats, previously attributed to dissociation within the A-V node, were shown to be due to functional block of the right bundle branch. It was found that the refractory period (RP) of the right bundle branch often exceeded the functional refractory period (FRP) of the A-V node at slow heart rates, permitting an early premature atrial response to reach the ventricles before recovery of the right bundle. Vagal stimulation and rapid driving frequencies, by delaying the intranodal transit of the premature response, prevented the exposure of bundle branch block. Epinephrine in low doses sometimes facilitated its occurrence.
Premature responses initiated in the His bundle in open heart preparations were commonly blocked in the right bundle under conditions in which atrial premature responses were normally propagated to the ventricles. Evidence was obtained in such preparations that the portion of the right bundle system beyond the site of the block was activated retrogradely from the left side. Under certain conditions the retrograde activation process returned to the His bundle and the atrium as an echo.