bluuebunny/crossref_metadata_2025 huggingface dataset:
Hemodynamic Alterations Caused by Passive Changes in Body Position in Dogs with Chronic Atrial Septal Defects
Authors: de S. Amorim Dalmo , W. Marshall Hiram , Wolford John L. , Wood Earl H.
Published: June 2012

The effects of passive tilting on the circulatory pressures and on the magnitude of shunts across chronic atrial septal defects were studied in 11 dogs with closed chests. These determinations were performed with the dogs in four positions: 45-degree head-up, 45-degree head-down, right lateral decubitus, and left lateral decubitus. Control values were obtained with the animals in the supine horizontal position.

The 45-degree head-up tilt position was associated with an increase in the magnitude of the right-to-left shunt detected after injections of indicator into the inferior vena cava, while change from supine to the 45-degree head-down tilt resulted in a decrease or disappearance of a pre-existing right-to-left shunt detected after similar injections. These effects on the right-to-left shunt were not demonstrable after injections of indicator into the superior vena cava, either during the head-up or head-down tilt, in spite of identical alterations in circulatory pressures. A significant interanimal correlation between the magnitude of the changes in systemic or right atrial pressures and the magnitude of the changes in right-to-left shunts could not be demonstrated. Passive changes in posture from supine to 45-degree head-up or head-down positions were not associated with demonstrable systematic effects on the magnitude of the left-to-right shunts. It is postulated that the descent of the heart and diaphragm during the head-up tilt results in a closer anatomical relation between the ostium of the inferior vena cava and the defect in the atrial septum and consequently an increase in the preferential shunting of inferior caval blood through this defect. In these animals, changing the body position from the supine to the right lateral decubitus position was consistently associated with an increase in the magnitude of the left-to-right shunts across the atrial septal defect and an increase in pulmonary blood flow. Since these animals have preferential shunting of blood from the right lung in the left-to-right direction, it is believed that the increase in blood flow through the dependent right lung is responsible for the observed increase in the left-to-right shunt. The left lateral decubitus position was not associated with appreciable effects on pulmonary blood flow or left-to-right shunting of blood across the atrial septal defect.
Rapid Serial Angiography in the Investigation of the Pharmacology of Brain Circulation in the Dog
Authors: CANOSSI GIANCARLO , BRUNELLI BRUNELLO , CORTESI NICOLA , CARPI AMILCARE
Published: June 2012

The values of cerebral circulation time were determined by means of rapid serial angiography in the chloralosed dog under control conditions, after administration of strychnine and after injection of ergotamine. These results were compared with those obtained by the simultaneous registration of the intracranial venous pressure. Confirming previous observations made by means of this latter technique, the angiographic results showed that strychnine reduces the cerebral circulation time by provoking an increase in cerebral blood flow, whereas ergotamine causes a cerebral vasoconstriction, thereby increasing intracranial circulation time. Moreover, a statistically significant inverse correlation exists between the values of the intracranial pressure and the cerebral circulation time. New evidence of the relationship between the extra- and the intracranial circulation was obtained by the angiographic observations; these latter data are discussed in relation with the problem of the lability of cerebral vasoconstrictor reactions.
Pacemaker Failure in Complete Heart Block
Authors: ALBERT HAROLD M. , GLASS BERT A. , ANDONIE JACK A. , CRANOR KENNETH C.
Published: June 2012

Atrioventricular conduction blocks were produced in dogs, and ventricular stimulation was accomplished by the use of electrodes implanted either into normal myocardium or scar tissue on the myocardium. Stimulation through scar tissue requires several times the power necessary for stimulation through normal myocardium, but both are well within the limit of standard, commercially available, transistorized pacemakers. Failure of stimulation of the ventricle was not due to excessive scarring. Failure of stimulation was in every instance due to wire breakage or actual loss of contact between the wire and the myocardium.
Peripheral Vasoconstriction Associated with Hyperpotassemia
Authors: Sudak Frederick N. , Fulton George P.
Published: June 2012

Hyperpotassemia was induced in hamsters by intravenous infusions of potassium salts. The caliber of blood vessels (10 to 100µ in diameter) in the cheek pouch was measured and comparisons were made when serum potassium concentration was maintained at 9.0 (σ= ± 1.64 mEq./L.) for 10 to 14 minutes and again at 12.3 (σ= ± 1.14 mEq./L.) for 10 to 14 minutes. In unoperated controls, a significant degree of vasoconstriction occurred in all arterial vessels at both levels of hyperpotassemia. Venular constriction was found at the higher potassium concentrations. Sympathetic denervation of the blood vessels had no effect on the vasoconstrictor response. Adrenalectomy prevented vasoconstriction at a potassium level of 9.0 mEq./L., but vasoconstriction was still evident in small arterioles at higher potassium levels. Sympathetic denervation of blood vessels in adrenalectomized animals, or treatment of intact animals with Dibenzylene, prevented vasoconstriction produced by hyperpotassemia. These data indicate that peripheral vasocontriction associated with hyperpotassemia is an indirect effect of the potassium ion.
Endocrine Pacemaker for Complete Heart Block
Authors: Folkman Judah , Edmunds L. Henry
Published: June 2012

In dogs with complete heart block, adrenal medulla or thyroid autografts, or tri-idiothyronine tablets implanted into the myocardium produced a sustained elevation in heart rate for 24 to 96 hours. Exercise of the animal caused a further increase in heart rate. Electrocardiographic studies suggested that the faster pacemaker activity originated from the area of implantation of the grafts or the tablets. After implantation of either thyroid grafts or tri-iodothyronine tablets, a latent period of 8 to 12 hours occurred before the new pacemaker became active. Data suggest that the pacemaker shift and the increase in heart rate are due to a local increase in hormones provided by the autografts or by the tri-iodothyronine tablets. There was no effect on the heart rate when similar or higher doses of tri-iodothyronine were given systemically. The method of tri-iodothyronine implantation into the myocardium is valuable in the study of the action of this hormone. The technique has two unique advantages: the reaction remains localized, and the endpoint is signaled electrically. Reserpine suppresses the ability of implanted tri-iodothyronine to increase the heart rate. This suggests that normal catecholamine levels are required for the positive chronotropic action of tri-iodothyronine. Myocardial catecholamine concentrations were not increased around the implanted tri-iodothyronine tablets. If catecholamines are necessary for the action of tri-iodothyronine on the myocardium, this suggests that tri-iodothyronine causes sensitization of the myocardium to the catecholamines, rather than causing an accumulation of the catecholamines themselves. Fibrous encapsulation of endocrine transplants appears to prevent permanent pacemaker activity. In lieu of successful thyroid transplants, myocardial implantations of tri-iodothyronine as slow release pellets are potentially applicable for patients with complete heart block.
Lengths and Diameters of Peripheral Arterial Vessels in the Living Animal
Authors: Wiedeman Mary P.
Published: June 2012

Measurements of the length, diameter, and number of branches of arterial vessels were made from a distributing artery to the capillaries in a living bat. From the values so obtained, cross-sectional areas in various portions of the arterial bed were calculated. An almost linear decrease in the diameters of successively smaller vessels was found. There was also a linear relationship in the calculated total cross-sectional areas formed by the various vessels. The results are not in agreement with similar reports made by others using measurements from vessels in a fixed preparation.
Effect of Tourniquet Shock and Acute Hemorrhage on the Circulation of Various Organs in the Rat
Authors: Takács Louis , Kállay Kálmán , Skolnik Josephine H.
Published: June 2012

Cardiac output, blood pressure, and organ fractions of cardiac output, except the brain, were determined in rats subjected to tourniquet shock and to hemorrhage. Bleeding involved the withdrawal of 23 and 32 ml./Kg. blood, respectively, and determinations were carried out 5 to 20 minutes after bleeding. Sapirstein's "indicator fractionation" method with Rb
86
was used for the determination of the cardiac output fractions. Blood flow and circulatory resistance of the organs were calculated from the experimental data. Cardiac output was not measured after severe (32 ml./Kg.) hemorrhage. In tourniquet shock at 50 mm. Hg blood pressure, the cardiac output and the blood flow in all organs decrease while vascular resistance of the skin and of the "carcass" (skeleton, muscles, endocrine organs) increases. The heart, "lung," and the liver fractions of cardiac output increase, renal and skin fractions decrease. After moderate hemorrhage at 47 mm. Hg blood pressure, cardiac output and the blood flow of the organs are low. Vascular resistance of all organs other than the heart and the "lung" rises. Cardiac output fractions of the heart, "lung," and "carcass" increase; renal and cutaneous fractions decrease. In severe hemorrhage, the redistribution of cardiac output has a similar tendency but is usually more pronounced.
Effects of Hemorrhagic Shock on Vascular Permeability to Red Blood Cells
Authors: Djerassi Isaac , Roy Albert
Published: June 2012

The lymph collected from the left thoracic lymph duct of dogs in severe shock due to blood loss becomes grossly hemorrhagic. Reversible hemorrhagic shock is not accompanied by changes in lymph appearance or content of red blood cells. The increased levels of red cells in the lymph was observed prior to the appearance of the characteristic gross intestinal and peritoneal hemorrhages.
Disposal of Human Chylomicrons Administered Intravenously in Ischemic Heart Disease and Essential Hyperlipemia
Authors: Nestel P. J. , Denborough M. A. , O'Dea J.
Published: June 2012

Human lymph chylomicrons labeled in vivo with C-14 palmitate were infused into eight patients with ischemic heart disease and into eight control subjects. The mean rates of removal of radioactivity from the chylomicron fraction of the plasmas of these subjects were found to be the same in the two groups. Labeled chylomicrons were also prepared from the blood of six patients with ischemic heart disease and of six controls, and infused into six recipients as paired infusions. Radioactivity from chylomicrons obtained from patients with ischemic heart disease was as readily removed from the circulations of recipients as was radioactivity from chylomicrons obtained from control subjects. When lymph chylomicrons were infused into two patients with hyperlipemia, the rate of removal of chylomicron radioactivity was considerably less than normal and appeared to be related to the levels of endogenous esterified fatty acids.
Action of Lobeline and Capsaicine on Afferent Endings in the Pulmonary Artery of the Cat
Authors: Bevan John A.
Published: June 2012

A comparison has been made of the anatomical localization and some of the characteristics of the visceral afferent endings stimulated by capsaicine, lobeline, and phenyldiguanide. The reflex hypotensive responses to these drugs have been measured following injection into the right atrium and different positions of the pulmonary artery tree in cats anesthetized with α-chloralose. In comparison with the magnitude of the hypotensive responses to capsaicine, lobeline, and phenyldiguanide from the right atrium, the response to capsaicine and lobeline was small or absent on injection into the right or left branch of the pulmonary artery at the level of the hilum. The response to phenyldiguanide was the same on injection at these two positions. The latent period between the injection and the reflex responses to capsaicine and lobeline, and the sensitivity of these responses to blocking doses of sodium pentobarbital and procaine hydrochloride were the same. Tetraethylammonium chloride will block the reflex action of lobeline in doses that have little effect on the reflex action of capsaicine. It is concluded that, in the cat, the capsaicine-and lobeline-sensitive receptors have a similar distribution and are probably situated in the pulmonary artery and the extrapulmonary part of its main branches and that these are anatomically separate from those stimulated by phenyldiguanide.
Effect of Angiotensin Infusion on Regional Blood Flow and Regional Vascular Resistance in the Rat
Authors: Mandel Morris J. , Sapirstein Leo A.
Published: June 2012

The effects of infusions of angiotensin of 0.05 to 0.5 µg./Kg./min. on the cardiac output, arterial blood pressure, and regional blood flow in the rat have been measured. Angiotensin increases the blood pressure without increasing the cardiac output; the total peripheral resistance is increased. Territorial resistances show varying degrees of increase, ranging from the cerebral vascular resistance, which is reduced or unchanged, to the renal vascular resistance, which shows a 100 to 200 per cent increase. The smallest increases in resistance in other organs are seen in the heart and lungs, which are unchanged, and the spleen and adrenal, which show minimal elevations. Larger changes are seen in the carcass, gut, and skin. The overall appearance of the changes in the distribution of blood flow in the animal infused with angiotensin suggests that blood flow is diverted from the kidneys to those organs most concerned with the immediate response of the organism to an emergency.
Vasoactive Substances in Blood and Urine of DCA Hypertensive Rats
Authors: Rosas Ramon , Croxatto Hector
Published: June 2012

The effect of intravenous injection of rat anephrotensin on rats treated with DCA for periods of up to 30 weeks was studied. It was found that in these animals, anephrotensin raises blood pressure, whereas in controls it acts as a depressor. Blood serum of DCA-treated rats yielded greater anephrotensin activity after acid incubation than did that of controls. Treated animals excreted, through the kidneys, more anephrotensin-like substance than controls. The pressor effect of the homogenized kidneys of these animals was less than that of controls; this is attributed to decrease in renin. Higher anephrotensin yield and the pressor response to anephrotensin were found to occur previous to the onset of hypertension; this suggests a causal relationship with the hypertension-provoking mechanism. The observations point to a similarity between DCA-treated and nephrectomized rats.
Effectiveness of 1-Dimethylaminoethyl-4-benzylpiperidine (IN379) in Prevention and Regression of Experimental Atherosclerosis in the Rabbit
Authors: O'Dell Thomas B. , Napoli Martha D. , Miller Lowell D. , Cavallito Chester J.
Published: June 2012

The compound, 1-dimethylaminoethyl-4-benzylpiperidine (IN379) has been shown to possess antiatherogenic properties based on the results obtained from experimental studies in rabbits. Two methods were employed to induce the experimental atherosclerosis. One was a short-term procedure involving the use of large doses of epinephrine and thyroxine, while the other procedure consisted of feeding the animals a high cholesterol diet over a more prolonged period of time. The effectiveness of the compound both as a prophylactic measure and on the regression of the atherosclerosis has been determined using the two methods. The influence of IN379 was found to be consistently favorable, although its effect was most marked in the prophylactic experiments.

The antiatherogenic properties of this compound are not related to influences on blood cholesterol content, in fact, hypercholesterolemia is not depressed by the drug. Attempts are made to correlate the antiatherogenic activity with other findings and pertinent observations are discussed.
The Metabolism of Angiotensin II
Authors: Wolf Robert L. , Mendlowitz Milton , Gitlow Stanley E. , Naftchi Nosrat
Published: June 2012

1. I
131
-labeled angiotensin II has been employed to study the metabolism of this polypeptide.

2. Following the intravenous administration of angiotensin II-I
131
to normotensive and untreated primary benign hypertensive subjects, a slower angiotensin II degradation rate and a larger final volume of distribution of angiotensin II-I
131
was found in the hypertensive than in the normotensive patients. The slow rate of degradation of angiotensin II may be responsible for the increased quantity and concentration of this polypeptide in the body fluids.

3. Greater quantities of angiotensin II-I
131
are degraded in vitro by sera from untreated primary benign hypertensive patients than from normotensive or secondary renal hypertensive patients. There is evidence for the presence of a serum factor or factors enhancing angiotensin II-I
131
degradation and for the presence of a heat labile inhibitor.
Cancellation of Electrocardiographic Effects During Ventricular Excitation
Authors: Abildskov J. A. , Klein Robert M.
Published: June 2012

Theoretical and experimental estimates of the amount of cancellation of electrocardiographic effects of ventricular excitation have been carried out. The theoretical estimate was based on the excitation sequence reported by Scher and consisted of comparing the total length of excitation fronts at several moments in the activation process with a measurement of the uncanceled portions of these fronts.

Experimental estimates in 10 dogs were based on the relative areas of spatial magnitude curves during normal ventricular excitation and during stimulation of the ventricular site yielding the largest magnitude curve area. A theoretical estimate of the cancellation to be expected during ventricular stimulation was also carried out. The theoretical estimate of cancellation of electrocardiographic effects during normal ventricular activation was 71 per cent, while the experimental estimates varied from 51 per cent to 80 per cent, with an average of 66 per cent.
Atherosclerosis
Authors: Harman Denham
Published: June 2012

Cholesterol-induced rabbit atherosclerosis was inhibited by the antihistaminic, chlorpheniramine, given orally at a rate of either 2, 4, or 8 mg./day/rabbit. Two attempts, both unsuccessful, were made to demonstrate directly the expected chlorpheniramine-mediated decrease in the permeability of the rabbit aortic wall to serum constituents: (1) study of sudan-red-stained frozen sections of aortas from rabbits fed a high-cholesterol diet for a few days, with and without added chlorpheniramine, and (2) a study of the effect of chlorpheniramine on the permeability of the inner aspect of the aorta to I
13l
-labeled serum albumin. A possible mechanism, based on aortic reaction to injury, is presented to account for the localization and development of atherosclerosis. This hypothesis led to the selection of chlorpheniramine for study as a possible atherosclerosis-inhibiting agent and underlies the belief that the atherosclerosis-inhibiting effect of this compound is due to inhibition of aortic reaction to injury.
Study of Spontaneous Congestive Heart Failure in the Dog
Authors: Wallace Charles R. , Hamilton William F.
Published: June 2012

Spontaneous cardiovascular disease has been found in dogs from the Savannah River Valley area, predominantly in the male house pet and hunting dog. The causes have been Dirofilariasis, chronic mitral valvular disease, and congenital cardiovascular defects. Cardiac stress in these dogs caused marked salt and water retention, increased blood volume, increased central venous and right heart pressures, and cardiac dilation and hypertrophy. These compensatory mechanisms were similar to those in man. Cardiac dilation was more pronounced in spontaneous failure than in experimental failure. Regression of cardiac dilation was very slow even after apparent compensation and clinical improvement. Plasma protein concentrations were decreased, but total extracellular protein mass was markedly increased. Sodium and potassium plasma concentrations were within normal range. Hyponatremia was occasionally observed in dogs as in man.
20
Dirofilariasis was characterized by marked pulmonary hypertension, caused primarily by pulmonary vascular changes rather than mechanical blockage. There was massive hypertrophy of the right ventricular myocardium. Heartworm dogs in congestive failure have a similar range of right heart pressure to experimental pulmonic stenosis dogs in failure.
21
Cage rest was of little therapeutic value in these dogs in congestive failure. Clinical response and physiological changes were remarkable with the use of saltabsorbing resin or digitalis compounds causing negative sodium balance. Digitalization of the dog required vigorous individual treatment controlled by clinical symptoms and P-R interval of the electrocardiogram. Acquired tolerance to digitalis required increased dosage levels every few months. The veterinary practitioner who recognizes the necessity of individual digitalization and the importance of detection and removal of thoracic fluid will be rewarded with improved clinical therapy of congestive heart failure. Experimental dogs during periods of severe cardiac stress can benefit from adequate digitalization. The similarity of biochemical and physiological changes in spontaneous heart disease, as it occurs in man and in dogs, affords an avenue for clinical research. This applicability to man is enhanced because the dog can be more comprehensively studied.
Interactions Among Dietry Fat, Protein, and Cholesterol in Atherosclerosis-susceptible Pigeons
Authors: Clarkson Thomas B. , Prichard Robert W. , Lofland Hugh B. , Goodman Harold O.
Published: June 2012

Atherosclerosis-susceptible pigeons fed cholesterol developed coronary atherosclerosis much more frequently than pigeons maintained on a cholesterol-free diet. Fewer of the cholesterol-fed pigeons fed a low protein diet developed coronary atherosclerosis than did cholesterol-fed pigeons on a high protein diet. Corn oil decreased the frequency of coronary atherosclerosis in cholesterol-fed pigeons. Limited evidence suggests that the coronary arteries and aortae in noncholesterol-fed birds are independent of each other in their susceptibility to atherosclerosis.
Determination of Relative Changes in Cardiac Output from Noncalibrated Earpiece Dye-Dilution Curves
Authors: Gabe Ivor T. , Tuckman John , Shillingford John P.
Published: June 2012

Many investigations require information on percentage changes in cardiac output rather than absolute values. This study investigates a simple method for measuring such relative changes, using noncalibrated earpiece dye-dilution curves. The basic principle involved is that, in an ideal system, the areas beneath successive dilution curves produced by equal injections of indicator are inversely proportional to the cardiac outputs. Applied to the earpiece dye-dilution curves, the restrictive assumptions relate mainly to linearity of response to blood concentration of dye and to the constancy of the blood volume of the ear. The method has been tested by recording simultaneous earpiece and arterial cuvette dye curves produced by injections of Coomassie Blue during changes in posture, exercise, and intravenous administration of vasoactive drugs. The relative changes in cardiac output predicted from the earpiece curves compared well with those from the arterial cuvette.
Collateral Circulation to Myocardial Regions Supplied by Anterior Descending and Right Coronary Arteries in the Dog
Authors: Chansky Moris , Levy Matthew N. , Zietke Harrison , Higgint Jacqueline , Nefson Geraldfno
Published: June 2012

The regional distribution of myocardial clearances of Rb
86
has been determined in dogs with intact coronary circulation, as well as in those with acute occlusions of the anterior descending or right coronary artery. In the intact heart, the Rb
86
clearance was rather homogeneous throughout the left ventricle and interventricular septum. The Rb
86
clearance for most of the right ventricle was less than that for the left ventricle. At the apex of the right ventricle, however, the clearance was greater and was quite variable from experiment to experiment.
Evidence Against Presence of Chromaffin Cells in Human Skin
Authors: Matz Leonard R. , Skinner Sandford L.
Published: June 2012

"Chromaffin cells" in human digital skin, described by previous workers, are readily recognized, but their granules do not produce the true chromaffin reaction of catecholamine, nor do they become green when subsequently stained with the Sevki technique. Although "chromaffin cells" differ morphologically from mast cells, they have similar tinctorial characteristics. Many cells were seen that could be accepted as either mast cells or "chromaffin cells." These cells in human skin are unaffected by intra-arterial reserpine and had the normal appearance in three patients with chronic degeneration of the sympathetic nerves. It is suggested that the "chromaffin cells" are mast cell variants and are not involv1ed in the autonomic effector mechanism.
Flow of Labeled Blood in Small Cylindrical Tubes and Glass Bead Systems
Authors: Sheppard C. W. , Rhodes W. M.
Published: June 2012

The transport of T 1824 by blood has been studied in glass bead columns and small cylindrical tubes. Technical improvements include a method for transilluminating blood in tubes of less than 1 mm. radius, permitting the observation of the outflowing dye spear. Curves of dye concentration in samples collected at the outflow are expressed in terms of τ and F (τ). These variables represent, respectively, the fraction of system volume displaced and the fraction of dye collected per unit τ interval. Results for blood and for an aqueous perfusion medium were closely similar in both the tube and bead experiments. In the tube experiments fair agreement was obtained between theoretical and experimental curves, but data in the smaller tubes were more subject to turbulent disturbances which could not always be precisely controlled.
Factors Influencing Pulmonary Hypertensive Response to 5-Hydroxytryptamine
Authors: Duteil Jacques J. , Aviado Domingo M.
Published: June 2012

The pulmonary hypertensive response to 5-HT in the dog heart-lung preparation is largely due to pulmonary vasoconstriction. There is an unexpected fall in aortic blood flow but no rise in left atrial pressure. In intact dogs the pulmonary hypertensive response is accompanied by an increase in pulmonary blood flow which is in turn partly reduced by upper thoracic sympathectomy. It is suggested that the rise in pulmonary blood flow is partly a sympathetic reflex initiated by pulmonary vasoconstriction by 5-HT.
Reproducibility of Results obtained with Indicator-Dilution Technique for Estimating Cardiac Output in Man
Authors: Sleeper Julian C. , Thompson Howard K. , McIntosh Henry D. , Elston Robert C.
Published: June 2012

The reproducibility of the indicator-dilution estimation of cardiac output was assessed by evaluating pairs of indicator-dilution curves recorded simultaneously from normal subjects and patients by two similar linear densitometers. Measurement error was defined by comparison of 90 simultaneous measurements obtained from the same needle; two standard deviations of the difference equaled 430 ml./min. (6 per cent of the mean cardiac output). A much larger variation resulted when 159 simultaneous cardiac output determinations, sampling from the brachial and femoral arteries, were compared (two standard deviations of the difference equaled 1,200 ml./min. or 20 per cent of the mean cardiac output). Intermediate values were obtained in a comparison of 29 simultaneous measurements from the radial and brachial arteries of the same arm. The larger deviations between the simultaneous measurements from different arteries suggested nonuniform distribution of dye. The discrepancies between the paired cardiac output determinations were larger and more frequent when peripheral blood flow alterations were produced. However, the nature of dye-distribution abnormalities and the mechanisms whereby peripheral arterial flow influence the dye-dilution cardiac output measurement were not evident.
New Electrode for Taking Electrocardiograms of Animals
Authors: Herrmann George R.
Published: June 2012

New types of electrodes for taking electrocardiograms on lightly or locally anesthetized animals of various sizes from baboons to mice have been developed and are herewith described.
Exchange of Blood Between Pulmonary and Systemic Circulations via Bronchopulmonary Anastomoses
Authors: Aramendia P. , De Letona J. Martinez L. , Aviado D. M.
Published: June 2012

In anesthetized dogs, the dye-dilution technique was applied to detect the transfer of blood between the bronchial and pulmonary vessels. The injection of Cardio-green into the pulmonary artery did not show a double peak in the dye-concentration curve of blood in the azygos vein. This does not exclude the possibility of a shunt from the pulmonary artery to the bronchial veins because the flow of the dye may take longer to reach the bronchial veins than does that from the bronchial artery. The injection of the dye into the left ventricle with sampling of the blood in the left atrium showed a double peak in the dyedilution curve. The latter is interpreted to indicate blood flow from the bronchial arteries to the pulmonary vessels via the bronchopulmonary anastomoses. In five dogs, the mean value for bronchopulmonary flow was 8 per cent of left ventricular output. The corresponding flow values were increased in three dogs with chronic ligation of the left pulmonary artery, not increased in four dogs with pulmonary embolization, and reduced in two dogs subjected to inhalation of heat. All these results suggest that previous estimates of 1 per cent for bronchial flow may be an underestimation, but the maximum value of 8 per cent in anesthetized dogs calculated by the dye-dilution technique will have to be reevaluated by other methods.
Effect of Chelation on Phosphorus Metabolism in Experimental Atherosclerosis
Authors: McCann D. S. , Koen Ann , Zdybek Geraldine , Boyle A. J.
Published: June 2012

MgNa
2
EDTA is shown to have an ameliorating effect of fat-induced atherosclerosis in rabbits. The compound was shown to decrease not only the general extent of atheromatosis, but to influence phosphate metabolism in induced atherosclerosis. Some credence is lent to a previously outlined hypothesis suggesting that the parathyroids mediate this effect.
Electric Shock Hazards in Cardiac Catheterization
Authors: Weinberg Daniel I. , Artley John L. , Whalen Robert E. , McIntosh Henry D.
Published: June 2012

1. These studies demonstrate that ventricular fibrillation can be produced in anesthetized, mechanically ventilated dogs by a current as low as 35 microamperes and a voltage as low as 0.06 volt.

2. Analysis of circuits of medical electronic equipment which is usually considered safe indicates that such low current levels may exist in the heart during catheterization.

3. The safety procedures established for our laboratory to minimize the hazard of electric shock are presented.
Dynamics of Carotid Sinus Elasticity During Pressor Reaction
Authors: Gero Ján , Gerová Mária
Published: June 2012

The volume-elasticity coefficient of the sinocarotid region, in vivo and in situ, in experiments on anesthetized dogs, was studied in the course of an induced pressor reaction in order to elucidate some controversial questions concerning the role of the distensibility of the sinus wall in the mechanisms of excitation of the sinocarotid receptors. The coefficient of volume-elasticity, calculated as pulse pressure/pulse volume ratio, was evaluated in relation to mean B.P., recorded simultaneously. Changes in the coefficient of elasticity of the sinocarotid region were found to precede compensation of the pressor reaction, viz., in the period of compensation the coefficient of elasticity of the sinocarotid wall--under otherwise equal physical conditions--was lower than in the period of rising pressure. The above-mentioned relations can be ascertained also after resection of the Hering nerve, i.e., after deafferentation and serious injury to the efferent innervation of the sinocarotid region. These changes are probably brought about by an automatic myogenic activity of smooth muscles of the vascular wall. The significance of the results obtained is pointed out in relation to the problems concerning the mechanism of excitation of the receptors of the sinocarotid region, especially with regard to the dependence of excitation of these receptors on distensibility (coefficient of elasticity) of the sinus wall.
DNA Synthesizing Cells in Rabbit Heart Tissue After Cholesterol Feeding
Authors: Spraragen Sanford C. , Bond Victor P. , Dahl Lewis K.
Published: June 2012

Suggestive evidence that cholesterol feeding may increase the number of thymidine-H
3
labeled cells in the heart tissues of rabbits was presented. This increment appeared to be primarily restricted to the interstitial cells and was not related to associated degenerative, necrotic, or inflammatory changes.

Evidence of DNA synthesis was also found in capillary endothelial cells and, rarely, in what were considered to be myocardial muscle cells.
Ventricular Response to Increased Outflow Resistance in Absence of Elevated Intraventricular End-Diastolic Pressure
Authors: LEVY MATTHEW N. , IMPERIAL ELIAS S. , ZIESKE HARRISON , Geraldine Nelson
Published: June 2012

In the isolated, supported, canine heart preparation, the response of the left ventricle to augmented outflow resistance was compared under conditions in which ventricular end-diastolic pressure and volume were increased and in which the pressure and volume remained virtually constant. The compensatory changes were much greater when end-diastolic pressure and volume were increased, even if these alterations in pressure and volume subsequently returned to or toward control levels. Immediately after resistance was augmented, peak ventricular power and stroke work diminished to less than control values. Within a very few beats, however, both of these parameters rose to exceed control levels. However, definite adaptive changes were also observed under conditions in which ventricular dimensions and pressures did not change appreciably, even temporarily. After a similar initial reduction in peak power and work after resistance was increased, peak power rose progressively to a value still significantly below control, while stroke work attained control levels by the end of a mean interval of 32 seconds of increased resistance. The intrinsic adaptation of the ventricle to increased resistance per se undoubtedly contributes to the total compensatory response, even under conditions in which diastolic stretch of the ventricle plays a major role.
Effect of Stimulation of Hypothalamus and Reticular Activating System on Production of Cardiac Arrhythmia
Authors: ATTAR HOUSHANG J. , GUTIERREZ MARIO T. , BELLET SAMUEL , RAVENS J. R.
Published: June 2012

Changes in blood pressure and the electrocardiogram were studied before and after the stimulation of the hypothalamus (anterior, lateral, and posterior) and the reticular formation of the pons in anesthetized cats.

The stimulation of the anterior hypothalamus produced a rise of blood pressure and usually bradycardia; tachycardia was rarely observed. Arrhythmias were not observed, and the electrocardiographic changes consisted only of slight ST elevation and deepening of the T waves. Stimulation of the lateral hypothalamus produced a rise in blood pressure of a lesser magnitude than that of the anterior hypothalamus but was associated with a transitory phase of A-V dissociation and frequent premature systoles. Stimulation of the posterolateral hypothalamus resulted in the same rise in blood pressure as that of stimulation of the lateral hypothalamus and was accompanied by nodal rhythms, aberrant ventricular conduction, and fusion beats. Stimulation of the reticular formation produced a rise in blood pressure similar to stimulation of the lateral and posterolateral hypothalamus and was associated with slight tachycardia, widening of the QRS complexes, transitory A-V dissociation with nodal escapes and ectopic beats of ventricular origin, and fusion beats.

These findings suggest that: (1) the hypothalamus serves as a pathway for cardiac neurovegetative stimuli, probably via the reticular formation, producing predominantly sinus node depression; (2) the posterolateral hypothalamus and reticular formation have similar functions in the production of cardiac arrhythmia.
Cell Volume, Plasma Volume and Cell Percentage in Splanchnic Circulation of Splenectomized Dogs
Authors: CHIEN SHU
Published: June 2012

The circulating splanchnic cell and plasma volumes were measured with the regional dilution technique in splenectomized dogs under sodium pentobarbital. For a 10-kg dog, the average circulating splanchnic cell volume is 56 (SE
m
= 5.0) ml and the average circulating splanchnic plasma volume is 98 (SE
m
= 7.2) ml. These values represent 20% of the total plasma volume respectively. The splanchnic cell percentage, averaging 36.3% (SE
m
= 1.32%), is significantly lower than the large vessel cell percentage (average 42.4%) and is almost equal to the overall cell percentage. The splanehnic F
cells
value averages 0.86 and is almost the same as the overall F
cells
value. Therefore, the splanchnic circulation contains a portion of the total "extra plasma" in proportion to the blood volume in this region. The splanchnic mean circulation time of the plasma (average 42 seconds) is significantly longer than that of the cells (average 33 seconds).
Hemodynamics of Dogs in Histamine Shock, with Special Reference to Splanchnic Blood Volume and Flow
Authors: CHIEN SHU , KRAKOFF LAWRENCE
Published: June 2012

After the subcutaneous injection of histamine (3 mg/kg), changes in splanchnic and systemic circulation were studied in splenectomized dogs under sodium pentobarbital. The estimated splanchnic blood flow (BSP clearance and extraction) decreased by 67%. The extent of the decrease was almost the same as that for the mean arterial pressure; thus the splanchnic vascular resistance remained unchanged. This unchanged splanchnic resistance was ascribed to a combination of arteriolar dilatation and hepatic venoconstriction, and the latter was indicated by the increase in the wedged hepatic venous pressure in the face of a decreased flow. The ciculating splanchnic blood volume (equilibration technique) was not significantly changed after histamine, but there was a decrease in the splanchnic cell percentage. Therefore, the evidence indicates that during histamine shock there was a shift of blood from the hepatic veins to the capillaries, rather than a pooling of blood in the splanchnic circulation. The decrease in the splanchnic cell percentage was about the same as the decrease in the overall cell percentage. The venoconstriction in the hepatic circulation and probably also that in the other circuits contributed to a reduction in venous return. The cardiac output (indicator dilution method) decreased by an average of 51%. The total peripheral resistance decreased by an average of 39%. The drastic and persistent arterial hypotension in histamine shock was due to decreases in both the cardiac output and the peripheral resistance.
Hypertension and Increased Hindlimb Vascular Reactivity in Experimental Coarctation of the Aorta
Authors: NOLLA-PANADES JUAN
Published: June 2012

Experimental coarctation of the aorta has been produced in rats. Animals with the clip above both renal arteries have been compared with animals with the clip below both renal arteries and with dummy operated rats. The fore- and hindlimb blood pressures, heart weights and perfusion pressure, and norepinephrine responses of the isolated perfused hindquarters have been measured.

Only the animals with a clip above the renal arteries developed hypertension and hypertrophy of the heart. The increase in blood pressure was progressive, requiring about 10 days to reach hypertensive levels. Such animals showed an increase in the norepinephrine responses and in the perfusion pressure of hindlimb blood vessels when compared with either of the other two groups. The differences are statistically significant. In rats with clips above the renal arteries, there is a highly significant regression line of hindlimb norepinephrine responses on hindlimb perfusion pressure and of either of these values on heart weight.

It is considered: (a) that the hypertension in experimental coarctation of the aorta is not purely mechanical and the kidneys are essential for the development of this type of hypertension; and (b) that the increase in the norepinephrine responses and in the perfusion pressure found in the hindquarter vascular bed of rats with coarctation of the aorta above the renal arteries is not secondary to the hypertension as such, but in some way is related to the mechanism that produces the hypertension in experimental coarctation of the aorta.
Effects of Isoproterenol on Carbohydrate Metabolism of Isolated Canine Heart
Authors: WINTERSCHEID LOREN C. , BRUCE ROBERT A. , BLUMBERG JACK B. , MERENDINO K. ALVIN
Published: June 2012

Chronotropic and inotropic effects of intraarterial infusion of isoproterenol were monitored in the isolated, metabolically supported preparations of the canine heart.

The time-dosage relationship was found to be hyperbolic over a narrow range of concentration of isoproterenol. Increasing concentration beyond the optimal range by a factor of about two produced arrhythmias and A-V conduction defects.

Oxidative metabolism increased significantly and proportionally to heart rate.

Since utilization of glucose remained the same, pyruvate utilization increased slightly and lactate was excreted; the augmented oxidative metabolism could not be accounted for by the observed changes in carbohydrate substrates.

Myocardial glycogen concentrations were insignificantly changed during this inotropic stimulation.
Murmurs Arising from Ductus Arteriosus in Normal Newborn Swine
Authors: EVANS J. R. , ROWE R. D. , DOWNIE H. G. , ROWSELL H. C.
Published: June 2012

The natural history of murmurs arising from the ductus arteriosus was investigated in normal newborn swine and compared with observations in other animals and infants at term. Ausenltation of 206 swine examined between birth and two weeks of age revealed a high incidence of continuous murmurs in the first six hours of life, crescendo systolic murmurs in 5% to 10% of animals during the first 24 hours and early systolic murmurs in a large proportion of the animals throughout the first week. Absence of a murmur was rare one to two hours after birth but, by 24 hours, less than 50% of the swine had murmurs of any type and after one week only one of 34 animals studied had a murmur. The continuous murmur was often preceded or followed by a crescendo systolic or early systolic murmur and it is proposed that all three murmurs arise from the ductus arteriosus under different conditions.

Internal sound recordings with a phonocatheter in the thoracic aorta demonstrated a systolic murmur loudest at the orifice of the ductus arteriosus in all swine in the first six hours of life and in a decreasing proportion of animals thereafter. Evidence is presented to suggest that this murmur is closely linked to patency of the ductus arteriosus but is different in origin from the murmur normally heard on auscultation of the chest. In four animals under six hours of age the phonocatheter passed through the ductus into the pulmonary artery and a continuous murmur was recorded. In two older swine the phono-catheter traversed the ductus but in these cases the murmur in the main pulmonary artery was confined to systole.

Since the occurrence of the different murmurs could not be satisfatorily explained on the basis of the systolic pressure gradient across the ductus nor on the basis of the anatomical size of the ductus at necropsy, it is postulated that the type of murmur generated is a reflection of the degree of narrowing of the lumen of the ductus produced by active constriction of its muscular wall during life.
Desmosterol Deposition in Human and Experimental Atherosclerosis
Authors: HERNDON JAMES H. , SIPERSTEIN MARVIN D.
Published: June 2012

The role of desmosterol in the production of atherosclerotic plaques has been studied. By means of gas chromatographic analysis, it has been possible for the first time to show that in patients treated with triparanol, even for short periods of time, desmosterol does contribute to the sterol deposition. Furthermore, in the induced atherosclerotic plaques of rabbits desmosterol has been found to deposit at least as readily as does cholesterol. It is concluded from these observations that the replacement of serum cholesterol with desmosterol does not seem to offer a rational approach to the treatment of atherosclerosis.
Relationships Between the Release and Tissue Depletion of Norepinephrine from the Heart by Guanethidine and Reserpine
Authors: HARRISON DONALD C. , CHIDSEY CHARLES A. , GOLDMAN ROBERT , BRAUNWALD EUGENE
Published: June 2012

The release of norepinephrine from the heart of anesthetized open-chest dogs has been determined both after the intravenous administration of guanethidine (15 mg/kg) and after reserpine (3 mg/kg) by measuring the plasma norepinephrine concentration with the fluorometric method (THI) in bloods obtained simultaneously from the coronary sinus and femoral artery. In four dogs following the administration of guanethidine, norepinephrine release into the coronary sinus blood occurred and persisted for two to three hours. This release of norepinephrine was accompanied by and adrenergic response of similar duration. The norepinephrine content of atrial appendage was reduced by 24% of control at four hours in these dogs and to extremely low levels in three other dogs 24 hours after guanethidine administration. Thus, the reduction of the tissue content of norepinephrine continued after measurable release of norepinephrine into the coronary sinus blood had ceased.

In four dogs following reserpine administration the adrenergic response was consistently smaller, and detectable release of norepinephrine into the coronary sinus blood was found transiently only in one dog. However, the norepinephrine content of atrial appendage was reduced by an average of 65% of control values at four hours. These findings suggest a difference in the mechanism of norepinephrine depletion in the period immediately after administration of guanethidine and reserpine.
Comparison of Central and Peripheral Injection Sites in the Estimation of Cardiac Output by Dye Dilution Curves
Authors: BOUSVAROS GEORGE A. , PALMER WILFRED H. , SEKELJ PAUL , MCGREGOR DAURICE
Published: June 2012

The validity of cardiac output values from injections of indicator into a peripheral vein was tested. Dye dilution curves resulting from injections of Coomassie Blue dye alternately from peripheral and central sites were obtained in 20 subjects. Peripheral injections in which the dye was not flushed into the circulaton were in a large percentage of cases unreadable. In those which could be read the area under the curve was larger and the cardiac output on the average 8.5% lower than the values obtained from paired flushed injections. Curves from flushed peripheral injections had larger time components and lower concentration of indicator than those from paired central injections. There was no systematic difference in the cardiac output values derived from the two sites. In man, contamination of the primary curve by recirculation of dye does not seem to cause significant error when the indicator is flushed into the venous system in the manner described.