bluuebunny/crossref_metadata_2025_split huggingface dataset:
Combined Sympathetic Suppression and Angiotensin-Converting Enzyme Inhibition in Congestive Heart Failure
Authors: Manolis Athanasios J. , Olympios Christoforos , Sifaki Maria , Handanis Stelios , Cokkinos Dennis , Bresnahan Margaret , Gavras Irene , Gavras Haralambos 
Published: June 2012

Neurohormonal activation is a pathogenic contributor and prognostic marker in congestive heart failure (CHF). While angiotensin-converting enzyme (ACE) inhibition is now first-line therapy, sympathetic inhibition has only lately been proposed to this aim. Recently, we reported improvement of preload parameters by sympathetic suppression with clonidine. In the present paper we studied the effects of a single oral dose of clonidine 0.15 mg+captopril 6.25 mg combination, compared with captopril 6.15+placebo in a single-blind parallel study on 16 patients with Class III or IV CHF (13 males, 3 females, aged 62±8 years, with an ejection fraction of 33±8%). Hemodynamic and hormonal measurements were taken at baseline after a diagnostic cardiac catheterization and again 2 hours after treatment. The results indicate that preload parameters such as RAP, PCWP and MPAP decreased significantly with the combination therapy but not with captopril alone. On the contrary, SVR decreased significantly with both treatments and SVI increased significantly with both—but the latter change was significantly greater with the captopril/clonidine combination than with captopril alone. Suppression of plasma norepinephrine occurred with the combination only (evidently attributable to clonidine), whereas plasma renin activity increased with both regimens, due apparently to captopril.
Our results indicate that the combination of clonidine with captopril induces significant improvements in both preload and afterload parameters of CHF and correction of activated neurohormones, suggesting additive hemodynamic and hormonal benefits from the two treatment modalities.
Relation Between Blood Flow and Contraction Force in Active Skeletal Muscle
Authors: Hirvonen Leo , Sonnenschein Ralph R. 
Published: June 2012

The relationships between blood flow and contraction force in intermittently contracting eat skeletal muscle during alterations of flow by various procedures were studied.
When flow only to the active gastrocuemiussoleus was measured, mechanical reduction in perfusion pressure, sympathetic chain stimulation and intra-arterial norepinephrine and epinephrine infusion were found to have esscritially identical effects in producing reduction in muscle force proportionate to that in blood flow. When flow in the whole leg musculature was measured while either the gastrocnemius-soleus or the quadriceps was active, varying results were obtained with these procedures which could be ascribed to differenees in response of vessels in active and resting muscles. During the carotid sinus reflex some vasoconstrictor activity occurred in active muscle. On the assumption that the maximal, muscle force is an index of the nutritional component of the flow, it may be inferred that, in general, those procedures in which total flow was restricted produced no alteration in distribution of nutritional and non-nutritional flow within the active muscle.
Blood flow and muscle force were generally unaffected by concomitant stimulation in the hypothalamus of the sympathetic vasodilator system. An increase in flow and force occasionally was observed whien these were at low levels, or when a rise in arterial pressure occurred. The sympathetic vasodilator system produces no alteration in distibution of flow and would seem to play no role in the maintenance of blood flow and performance of normal active muscle.
A fundamental difference appears to exist in the responses of the vasculature of resting and active skeletal muscle; this difference is related to the interplay of specialized effects of the vasomotor innervations and the action of vasodilator metabolites.
Study of Heart Mitochondria and Glycolytic Metabolism in Experimentally Induced Cardiac Failure
Authors: SCHWARTZ ARNOLD , LEE KWANG SOO 
Published: June 2012

Studies were made on the biochemical activity of mitochondria and of homogenates obtained from normal hearts and from hearts after experimentally induced failure. The principal types of failure investigated were: "chronic" congestive failure and acute failure in the guinea pig. The "chronic" failure was induced in from 2 to 10 days by a partial constriction of the ascending aorta, while the acute type of failure was induced by a more severe aortic constriction of a similar type. Various physiological parameters were studied. The "chronic" animals exhibited tachycardia, elevated right ventricular systolic pressure and a significant depression of myocardial contractility. In addition, a highly significant increase in cardiac tissue mass was observed. Passive congestion of the liver, spleen, kidneys, and lungs was evident.
Mitochondria isolated from the hearts of guinea pigs in "chronic" failure exhibited a significant depression of metabolic activity. Thus phosphorylation associated with the oxidation of glutamate, succinate, or α-ketoglutarate was uncoupled in mitochondria isolated from the "failed" heart. Cardiac glycosides administered to animals with experimental cardiac failure did not alter the uncoupled state of the mitochondria, although these agents effected a significant improvement in cardiac contractility. The ATPase activity of the "failed" mitochondria was normal. Experiments concerning the localization of the site or sites of uncoupling of oxidative phosphorylation in the "failed" mitochondria revealed that the defect probably resided in the phosphorylation step associated with the electron transfer between cytochrome C to oxygen.
Homogenates prepared from hearts of chronically failing animals were markedly depressed with respect to oxygen and glucose consumption and lactic acid formation.
Mitochondria isolated from acutely failed guinea pig hearts exhibited a "mild" uncoupling of oxidative phosphorylation manifested as a decrease in responsiveness to a phosphate acceptor system. This was a graded effect, increasing in severity with increasing duration of aortic constriction.
On the basis of the present study, it is possible that uncoupling of oxidative phosphorylation in heart mitochondria may play a role in the development of congestive cardiac failure.
Chronic Carotid Sinus Compression in Dogs: A Study of Hemodynamic Changes with and without Sinus Denervation
Authors: Little J. Maxwell , Cordell A. Robert , Conrad Eugene A. 
Published: June 2012

In two groups of dogs the carotid sinuses were chronically compressed bilaterally by the application of plastic Wakerlin clamps. In the first series of three dogs, the carotid sinus nerves were sectioned and the adjacent vessel walls thoroughly cleaned. Chronic carotid sinus compression resulted in an increase in arterial systolic pressure, diastolic pressure, average arterial pressure, pulse pressure, and heart rate over a period of 422 to 485 days.
In the second series of five dogs, in which the carotid sinus innervation was preserved, chronic carotid sinus compression resulted in a variable but slight change in arterial systolic pressure, a consistent increase in diastolic pressure, a variable but slight change in average arterial pressure--with only one dog showing a consistent significant increase, a consistent decrease in pulse pressure, and a variable effect on heart rate over a period of 593 to 695 days.
The daily administration of 6 Gm. of sodium chloride per day to the second series of dogs resulted in no appreciable changes in pressure. However, there was a tendency for the heart rate to decrease, with three dogs showing a significant decrease. When the salt administration was stopped, the heart rates returned to values near those observed prior to salt administration.
The results suggest that in the first series of dogs, with the carotid sinuses denervated chronically, there is an increase in cardiac output and a decrease in peripheral resistance. In the second series of dogs, with innervation of the sinuses intact and with chronic compression, the results suggest a decrease in cardiac output and an increase in peripheral resistance.
Estimation of Left Ventricular Residual Volume in the Dog by a Thermodilution Method
Authors: Rapaport Elliot , Wiegand Bernard D. , Bristow J. David 
Published: June 2012

Thermodilution was used to estimate left ventricular volumes by the indicator-dilution principle. The results of multiple determinations in the same animal were in close agreement. Average values determined in 16 dogs anesthetized with a chloralose-urethane mixture were SV 18 ml., ESV 37 ml., EDV 56 ml., and CO 2.54 L./min. The ratio ESV/EDV averaged 66 per cent, which was significantly less than the ESV to EDV ratio of 79 per cent observed in 14 other dogs anesthetized with sodium pentobarbital and studied in a comparable fashion. This difference was attributed primarily to the myocardial depressant effects of the barbiturate anesthetic.
The ability to perform multiple determinations without "indicator" accumulation, to record the time-temperature curve directly at the base of the aorta without sampling through a catheter system, to avoid introducing substances into the circulation which may produce significant circulatory effects, and to perform calibration quickly and easily suggests that the thermodilution technique offers a simple, rapid, and reproducible method for estimating ventricular volumes.
Nucleic Acid Studies in Experimental Cardiomegaly
Authors: SUMNER ROBERT G. , MCINTOSH HENRY D. 
Published: June 2012

1. A group of weanling rats was made anemic by an Fe- and Cu-deficient diet consisting of cow's milk. An appropriate control group receiving Fe and Cu in addition to milk was also studied. After 86-105 days, the rats were sacrificed; hematocrit levels, heart weights, DNA, RNA, and protein concentrations were determined. Total DNA, RNA, and protein contents of the hearts were calculated.
2. Statistical analysis showed a significantly increased mean heart weight, decreased DNA concentration, increased RNA to DNA ratio, and increased total RNA and protein content in the hearts of the anemie group of rats versus the control rats. There were no statistically significant changes in RNA concentration or total DNA content of the hearts.
3. These data are interpreted as showing that the predominant cellular change in cardiae enlargement in the rat with dietary Fe-and Cu-deficiency is that of increase in size of the myocardial cell.
Detection and Measurement of Experimentally Produced Aortic Regurgitation by Means of Indicator-Dilution Curves Recorded from the Left Ventricle
Authors: ARMELIN EGAS , MICHAELS LEON , MARSHALL HIRAM W. , DONALD DAVID E. , CHEESMAN RICHARD J. , WOOD EARL H. 
Published: June 2012

In dogs studied without thoracotomy the detection of immediately appearing indicator in the left ventricle following its injection approximately 1 cm downstream from the aortic valve can be used as a reliable index of the presence or absence of aortic regurgitation.
With this type of injection and under the conditions of these experiments, the ratio of the area encompassed by the immediately appearing portion of the dilution curve recorded from the left ventricle to the area encompassed by the primary portion of the curve recorded at the femoral artery bears a close positive correlation (correlation coefficient: 0.9) to the severity of aortic regurgitation as estimated by back perfusion of the valve at necropsy.
Within limitations, the position of the tip of the sampling catheter in the left ventricle in dogs with aortic regurgitation is not an important determinant of the amount of immediately appearing indicator detected in this chamber. Furthermore, although the amount of indicator detected in the left ventricle following injections of very short duration is time-dependent, if the duration of the injection is extended to cover the full systolic or diastolic phase of one heartbeat or continues over one or more heartbeats, the exact timing of this injection in relation to the cardiac cycle is not an important determinant of this variable.
It is concluded that under these conditions the positive correlation established between the amount of immediately appearing dye detected in the left ventricle (expressed as the regurgitant fraction) and the severity of aortic regurgitation determined by back perfusion at necropsy can be used as a valid means of estimating the severity of aoritic regurgitation in dogs.
The applicability of this indicator-dilution method to the study of clinical aortic reguragitation merits further study.
Effects of Increased Transmural Pressures upon Atrial and Ventricular Rhythms in the Dog Heart-Lung Preparation
Authors: VICK ROBERT L. 
Published: June 2012

The effects of increased transmural pressures upon atrial and ventricular rhythms have been studied in the heart-lung preparation of the dog. Increases in right-heart pressure resulted in increased sinus rates when the SA node was intact. When the SA node was crushed and an A-V nodal rhythm revealed, increased right-heart pressure resulted in more rapid A-V nodal rhythms in some preparations while shifts to more rapid pacemakers, adjacent to the SA node, were detected in others. Independent ventricular pacemakers emerged during periods of elevated pressure in every preparation in which the sinus node had been crushed.
Left-heart pressure was increased by augmenting the systemic resistance, the minute volume, or both. In A-V dissociated hearts, epinephrine or metaraminol were administered to enable the generation of higher aortic pressures (above 150 mm Hg). During the periods of elevated pressure, new or increased pacemaker activity was seen in the independently beating ventricle.
These results and others cited show that atrial dilatation or elevated arterial pressure may participate in the genesis of some cardiac arrhythmias.
Influence of Reserpine and βTM 10 on Digitalis-Induced Ventricular Arrhythmia
Authors: Roberts Jay , Ito Ryuta , Reilly Joseph , Cairoli Vincent J. 
Published: June 2012

After catecholamine depletion by reserpine, the capacity of the digitalis materials to induce ventricular arrhythmia is diminished. In papillary muscles from cats pretreated with reserpine, the incidence of ouabain-induced extra beats is reduced. The dose of ac. stroph. necessary to induce ventricular arrhythmia in combination with vagal stimulation is increased by reserpine pretreatment. Threshold doses comparable to those in cats not pretreated with reserpine produced arrhythmia after the catecholamine stores were repleted with norepinephrine or isoproterenol.
In dogs with A-V block, βTM 10, an agent which prevents the release of catecholamines, markedly reduces the response of the ventricular pacemaker to ac. stroph.
Since the arrhythmias induced by large doses of ac. stroph. are not affected by reserpine pretreatment, it is concluded that while catecholamine release is the primary mechanism involved in the arrhythmia produced by small doses, another mechanism also plays a role in this action after larger doses.
Only in the dose of 10 mg/kg did it appear that catecholamine depletion did not account entirely for the action of reserpine. The ac. stroph. threshold dose was not increased to the same degree as with the smaller doses of reserpine, and the incidence of ventricular fibrillation induced by the large dose of ac. stroph was reduced.
Hypotension produced by reserpine and βTM 10 did not seem to be an important factor in depression of the responsiveness of the ventricular pacemaker to ac. stroph.
While the incidence of ouabain-induced extra beats was reduced by reserpine pretreatment, the action of ouabain to increase the tension developed by isolated papillary muscles was not affected.
Myocardial Blood Flow and Oxygen Uptake During Acute Red Cell Volume Increments
Authors: Regan Timothy J. , Frank Martin J. , Lehan Patrick H. , Galante James G. , Hellems Harper K. 
Published: June 2012

The role of red cell mass in the regulation of coronary blood flow and myocardial oxygen consumption has been examined after acute transfusion of sedimented red cells. Patients with substantial blood-loss anemia had a lower than normal left ventricular oxygen uptake, despite a high myocardial blood flow at rest. A 50% rise of hematocrit reduced coronary flow markedly. Although systemic arterial pressure, cardiac output, and left heart work rose, myocardial oxygen consumption was unchanged.
Red cell transfusion of normovolemic dogs resulted in a decrease of both myocardial flow and oxygen uptake associated with an elevation of time-tension index and left ventricular work, accelerated isometric contraction and prolonged systole. There was no evidence of ischemia or change of left ventricular hemodynamic parameters that would account for the reduced myocardial blood flow and oxygen uptake. These findings, in the presence of an increased oxygen carrying capacity and extraction, would appear to be related principally to enhanced blood viscosity.
Regional Distribution of Glycogen and Phosphorylase in the Ventricles of the Heart
Authors: JEDEIKIN LILLIAN A. 
Published: June 2012

In rat, rabbit, dog, and ox hearts, the glycogen concentration varied throughout the walls. The concentration gradient decreased from endocardium to epicardium in the right and left ventricles. In the septum, the interior part of the wall had a lower concentration of glycogen than tissue sections closer to the endocardial surfaces. The maximum values for glycogen concentration in endocardial sections were from two to six times higher than the minimum values. This gradient was much greater than the 30% differences observed between apex and base of the ventricles. Since our studies have demonstrated a very large variation for glycogen content in layers of myocardium parallel to sides of the ventricular wall, there is an obvious need for caution in sampling hearts for glycogen analysis.
In the ox heart, the right bundle branch and A-V node were dissected out, and the glycogen values were compared with those for the rest of the myocardium. Glycogen values of the conduction system, especially of the bundle of His, were considerably higher than for any part of the myocardium studied, indicating that the myocardial gradients observed may be related to distribution of the Purkinje fibers.
Phosphorylase values decreased from endocardium to epicardium in a pattern similar to that observed for glycogen, indicating a possible function in association with glycogen concentration.
In the hearts perfused with a glucose-free medium by the Langendorff technique, glycogen diminished throughout the heart, but the general pattern of gradients was preserved. This suggested that glycogen is utilized as an energy source for contraction.
Origin and Conduction of the Mitral Sound in the Heart
Authors: FABER J. JAB 
Published: June 2012

Mitral heart sounds were recorded by small microphones inserted in the heart muscles of dogs. Recordings showed that components having frequencies between 20 and 40 cycles/ sec originate at the base of the heart and travel from there to the apex. The velocity of conduction is in the order of 4 m/sec, so that the wavelengths can be calculated to be about 20 to 10 cm. At these frequencies the ventricle seems to vibrate as a whole. Components having frequencies higher than 40 cycles/sec could not be followed during their progression over the heart.
In the range from 20 to 160 cycles/sec, the mitral sounds recorded above and below the mitral valve were of opposite phase so that the mitral valve is the main elastic element responsible for the mitral sound. The combined masses of the heart and the blood in it constitute the inertia of the cardiohemic system. In this range of frequencies oscillations in transmural pressure and circumferential tension of the heart were synchronous and of the same phase.
The low velocity of conduction, the structural similarity between the heart and arteries, and the synchronism in the oscillations of transmural pressure and circumferential tension allow the conclusion that the mitral sound is conducted through the ventricle in the form of a transverse vibration, strictly analogous to the way pulse waves are conducted in arteries.
Myocardial Mural Thickness During the Cardiac Cycle
Authors: FEIGL ERIC O. , FRY DONALD L. 
Published: June 2012

The instantaneous and continuous thickness of the left ventricular wall was measured in ten dogs with a specially designed transducer. The thickness change during the "isovolumic" phase of systole was 11%. The average thickness increased an additional 10% during the ejection period of systole. These average values increased to 20% and 15% respectively with the administration of norepinephrine (approximately 0.001 mg/kg per minute).
Transverse and longitudinal epicardial are strains were compared with thickness strain of the myocardium. Assuming the myocardium is incompressible, reasonable agreement was found in the three strains, which lends support to the measurements that were made.
It is concluded that changes in the thickness of the myocardial wall during the cardiac cycle may be important in some considerations of the heart's performance.
Transmyocardial Temperature Gradient in Dog and Man: Relation to the Polarity of the T wave of the Electrocardiogram
Authors: REYNOLDS ERNEST W. , YU PAUL N. 
Published: June 2012

The transmyocardial temperature gradient was measured in both right and left ventricles and in the septum of the dog by percutaneous ventricular puncture, using a no. 21 thin-wall needle fitted with a thermocouple stylus. The outer half of the left ventricular myocardium was invariably warmer than the endocardium. The peak temperature of the right ventricle was located midway between the endocardium and epicardium. The midseptal region was found to have a higher temperature than either its right or left endocardial aspects. The left ventricular cavity was cooler than the right ventricular cavity by a mean of 0.1°C.
The transmyocardial temperature gradient was measured successfully in the left ventricle of two patients with cardiac disease. As in the dog, the outer layers of the myocardium were warmer than either the endocardium or cavity in these two patients. In one patient the T waves in the left precordial leads were negative and in the other the T waves were upright in the same lead.
The location of peak temperature consistently in the outer half of the left ventricular wall may partly explain the normal upright T wave and may contribute to a more rapid recovery in the outer layers of the ventricle compared with the inner layers. However, reversal of the T wave must be explained by other factors and it is apparent that the polarity of the T wave is not governed exclusively by the transmyocardial temperature gradient.
The transmyocardial temperature gradient may be explained partly on the basis of differences in heat removal by blood flow in the coronary system as well as in the ventricular cavity. The latter was found to be an important factor, because during ventricular fibrillation the transmyocardial temperature gradient was abolished.