bluuebunny/crossref_metadata_2025 huggingface dataset:
Red blood cell Li+-Na+ countertransport, Na+-K+ cotransport, and the hemodynamics of hypertension.
Authors: Weder A B , Fitzpatrick M A , Torretti B A , Hinderliter A L , Egan B M , Julius S
Published: June 2012

Red blood cell Li+-Na+ countertransport and Na+-K+ cotransport activities, home blood pressure, invasive systemic hemodynamics, and limb venous compliance were measured in 65 white men (23 normotensive, 22 borderline hypertensive, and 20 mild essential hypertensive subjects). Li+-Na+ countertransport activity was positively and significantly correlated with subject-determined home systolic blood pressure (r = 0.31, p less than 0.02) and with directly measured systolic (r = 0.29, p less than 0.02) and diastolic (r = 0.27, p less than 0.03) blood pressures in the hemodynamic laboratory, independent of potential confounding variables. Analysis of the hemodynamic determinants of blood pressure revealed a significant positive correlation of countertransport with vascular resistance (r = 0.30, p less than 0.02) but not with cardiac output or cardiac index. High red blood cell Na+-K+ cotransport activity was not independently associated with hypertension or with a characteristic hemodynamic pattern but was related to decreased venous compliance. Red blood cell Li+-Na+ countertransport deserves further study as a marker for the genetic substrate of human essential hypertension. Red cell Na+-K+ cotransport may be altered secondarily by factors related to high blood pressure and seems to be a valid marker for abnormalities of the venous system in hypertension.
Preserved cardiac beta-adrenergic sensitivity in early renovascular hypertension.
Authors: Davidson W R , Kawashima S , Banerjee S P , Liang C S
Published: June 2012

To determine the mechanism of blunted sympathetic reflex responses in early renovascular hypertension, we measured inotropic and chronotropic responses of the heart to beta-adrenergic stimulation in vivo and myocardial beta-adrenergic receptor number and adenylate cyclase activity in 10 dogs during an early stage of one-kidney renal hypertension. Mean aortic pressure was higher in the hypertensive dogs (152 +/- 4 mm Hg) than in eight sham-operated dogs (122 +/- 1 mm Hg; p less than 0.001), but heart rate, cardiac output, and left atrial pressure did not differ between the two groups. Blood pressure reduction with a direct-acting vasodilator, pinacidil, resulted in marked increases in heart rate (+97 +/- 12 beats/min) and rate of change of left ventricular pressure (dP/dt; +1447 +/- 367 mm Hg/sec) in normotensive dogs but only blunted heart rate (+54 +/- 12 beats/min) and minimal left ventricular dP/dt (+376 +/- 264 mm Hg/sec) responses in hypertensive dogs. In contrast, intravenously administered isoproterenol produced similar increases in heart rate and left ventricular dP/dt in the two groups. These two groups also did not differ in either left ventricular beta-adrenergic receptor number and affinity or basal, isoproterenol-stimulated, and fluoride-stimulated adenylate cyclase activity. Thus, despite blunted reflex responses to blood pressure reduction, hypertensive dogs showed neither reduction in chronotropic and inotropic responses to direct beta-adrenergic stimulation nor beta-adrenergic desensitization of the myocardium, as assessed by beta-adrenergic receptor number and adenylate cyclase activity. Blunted reflex responses in this model of early hypertension must be due to factors operating at some locus other than the beta-adrenergic receptor-adenylate cyclase complex.
Ventricular atriopeptin. Unmasking of messenger RNA and peptide synthesis by hypertrophy or dexamethasone.
Authors: Day M L , Schwartz D , Wiegand R C , Stockman P T , Brunnert S R , Tolunay H E , Currie M G , Standaert D G , Needleman P
Published: June 2012

Left ventricular hypertrophy or treatment with dexamethasone caused a 2.5-fold to threefold increase in both immunoreactive atriopeptin (AP) and AP messenger RNA (mRNA), primarily in left ventricular tissue. The combined treatments increased immunoreactive AP and AP mRNA more than either treatment alone. In the animals in which cardiac hypertrophy had been produced by abdominal aortic constriction, there was a decrease in atrial levels of AP and an increase in plasma levels of immunoreactive AP. The increase in left ventricular immunoreactive AP was confirmed by immunohistochemical staining of tissue from hypertrophied and/or dexamethasone-treated rats. The mRNA accumulated in the left ventricle was identical to atrial AP mRNA, as judged by transcriptional start site and by size on Northern blots. Because the mass of ventricular tissue is substantially greater than that of atrial tissue, the induced mRNA levels may represent a total abundance approaching one third of the total AP mRNA in the atria. High performance liquid chromatographic purification of ventricular extracts primarily demonstrated the presence of the high molecular precursor and small amounts of C-terminal peptide AP. Induction of ventricular AP (mRNA and peptide) may represent regression of the tissue to an earlier developmental form. These data provide a unique example of regulation of AP biosynthesis in nonatrial tissue.
Functional Analysis of the Vasomotor Innervation of the Dog's Hind Footpad
Authors: RANDALL W. C. , ALEXANDER W. F. , Cox J. W. , HERTZMAN A. B.
Published: June 2012

Vascular responses in the large central pad of the dog's foot were recorded during stimulation of the lumbosacral sympathetic trunk and correlated with the site of stimulation and the subsequent histologic analysis of the excised trunk. The resulting description of the preganglionic inflow and postganglionic outflow from the trunk demonstrated marked variations in the anatomic patterns of the vasomotor innervation of the footpad in various animals. Complete preganglionic denervation of this vascular bed required extirpation of the entire lumbar trunk caudalward as far as L-7 in addition to the interruption of those preganglionic pathways through the spinal nerves which do not pass through the sympathetic trunk.
Experimental Pulmonary Edema Following Rapid Carotid Infusion: Mechanism and Therapy
Authors: LUISADA ALDO A. , CONTRO STEPHEN
Published: June 2012

The mechanism and therapy of acute pulmonary edema are studied in animals with rapid intracarotid infusion of saline solution toward the brain. Sympatholytic drugs and heparin have a marked beneficial action and prevent the occurrence of pulmonary edema.
Some Observations on the Hepatic Venous Pulsation in the Anesthetized Dog
Authors: SANCETTA SALVATORE M.
Published: June 2012

Since direct evidence of transmission of propagated waves into the hepatic veins (liver pulse) has been lacking, pressure pulses were recorded in the hepatic vein of the anesthetized dog. A constant presystolic positive wave, amplified by venous congestion and pulmonic compression, is demonstrated and shown to be transmitted from the atrium. During tricuspid insufficiency, a second transmitted positive wave is inscribed late in ventricular systole.
The Distensibility Characteristics of the Portal Vascular Bed
Authors: ALEXANDER ROBERT S. , EDWARDS W. STERLING , ANKENEY JAY L.
Published: June 2012

The distensibility of the splanchnic portion of the portal system has been evaluated by studying pressure and volume changes with or without any interruption of blood flow. The results of these determinations indicate two types of distensibility of the system: (1) a rapid elastic distension representing relatively small volumes, and (2) a secondary phase of slow distension, designated "delayed compliance," which represents a significantly greater volume change. It is concluded that delayed compliance is of major importance in the pooling of blood in peripheral blood vessels under conditions of maintained elevation of venous pressure.
The Metachromatic Activity of Urine Following the Injection of Heparin
Authors: JAQUES L. B. , NAPKE E. , LEVY S. W.
Published: June 2012

Heparin was injected in man, dog, rabbit and sheep and the metachromatic activity (MA) of the urine measured directly or after precipitation with benzidine. The presence and amount of MA in the urine depended on route, size and time relations of the injection, but generally was much less than the MA of the heparin injected. An excretion product, uroheparin, has been described. It is concluded that following injection heparin may be (
a
) destroyed by heparinase, (
b
) degraded to uroheparin or (
c
) excreted unchanged. Following (
b
) or (
c
) metachromatic activity is found in the urine.
The Variable Arterial Pressure Response to Serotonin in Laboratory Animals and Man
Authors: PAGE IRVINE H. , McCUBBIN J. W.
Published: June 2012

Arterial pressure response to serotonin depends largely upon four main actions of the drug: direct vasoconstriction, a von Bezold-like reflex, transient ganglion blockade and peripheral inhibition of neurogenic vasoconstriction. The relative prominence of these actions differs depending upon the dose of serotonin, species tested and degree of pre-existing neurogenic vasoconstriction.
The Estimation of Peripheral Vascular Resistance to Varying Rates of Flow in the Isolated Rat Hindquarter
Authors: DOYLE A. E.
Published: June 2012

The relationship between flow and pressure was studied in the perfused hindquarters of the rat. The conclusion is drawn that peripheral resistance declines progressively with increasing intravascular pressure at various rates of flow, regardless of whether the vessels are relaxed or constricted.
Evidence for a Prolonged Biological Half-Life of Na
22
in Patients with Hypertension
Authors: DAHL LEWIS K. , SMILAY MALCOLM G. , SILVER LAWRENCE , SPRARAGEN SANFORD
Published: June 2012

The biological half-life of Na
22
was found to be significantly longer (
p
<0.01) in seven hypertensive adults than in eight normotensive adults on equivalent NaCl intakes. Calculations based on approximations of leanbody mass suggest that the hypertensive subjects may have a larger sodium pool to explain this disparity.
Basic Concepts in the Determination of vascular Volumes by Indicator-Dilution Methods
Authors: Grodins Fred S.
Published: June 2012

In this paper, we have considered some of the basic concepts underlying the measurement of vascular volumes by indicator-dilution methods. Granting the assumptions of stationary flow and homogeneous labeling of flowing blood, the classical Stewart-Hamilton prescription, V = Qt, provides a valid estimate of central volume. Although the boundaries of this volume can be precisely defined in terms of "time distances," the anatomic description is less definite. The classical treatment did not provide a theoretical model from which the form of the indicator-dilution curve could be deduced but a number of such models have now appeared. These include the mixing-chamber model of Newman and the stochastic models of Sheppard. The slope-volume based on Newman's model measures some fraction of the classical central volume, but precise anatomic boundaries probably cannot be assigned to it. We have attempted to show that so long as we deal with a linear system, the indicator-dilution problem, including recirculation, can be conveniently treated in terms of a block diagram-transfer function approach. Finally we have considered some of the theoretical and practical aspects of the measurement of ventricular volumes.

In conclusion, it might be appropriate to say something about mathematical models in general. Every such model is an abstraction which deliberately neglects certain features of the prototype in order to make possible the rigorous treatment of others. We should therefore not be disappointed to find that "no thoroughly defined system can be expected to mimic completely all of the phenomena of physiological importance."
5
What we should demand of a model is that it mimic enough of these phenomena to make it useful, and that it point the way to its own continuing improvement. If it does these things, it cannot help but be a contribution to the advancement of both theory and practice.
Observations on the Responses of Rats with Spontaneous Hypertension and Control Rats to Pressor Drugs and to Hexamethonium
Authors: Phelan E. L. , Eryetishir I. , Smirk F. Horace
Published: June 2012

The establishment, by selective breeding, of a colony of rats with a high incidence of spontaneous hypertension has been confirmed by a kymographic technique with femoral artery cannulation. The reaction of rats to several pressor drugs has been altered by selective breeding. In both control and inherited hypertensive rats, the initial level of the blood pressure prior to administration of the drug influences the magnitude of the responses to several pressor drugs but not to norepinephrine. If hypertensives are compared only with other hypertensives and controls with other controls, it is clear that high preinjection pressures have an inhibiting effect on the pressor responses to biologically and synthetically prepared angiotensin, to vasopressin, and possibly lessen also the responses to s-methyl
iso
-thiourea. When under experimental conditions the blood pressures of rats with inherited hypertension have fallen into the upper range of control rat blood pressures, the responses to epinephrine, vasopressin, s-methyl
iso
-thiourea and biological angiotensin are greater in the hypertensives than in the controls. The difference in the case of synthetic angiotensin is not statistically significant. In the case of norepinephrine, the responses are equal. Hexamethoniun reduced the blood pressures of inherited hypertensive and control rats to the same level.
Inhibition of Vaccinial Hemagglutinins by Sera of Patients with Coronary Heart Disease and Other Chronic Illnesses
Authors: Neff Beverly Jean , Ackermann W. Wilbur , Epstein Frederick H. , Francis Thomas
Published: June 2012

Serum inhibitory titers to the agglutination of chicken red cells by vaccinial hemagglutinin have been measured in persons with a variety of chronic diseases and in a control sample of the general population. Between the ages of 30 and 74, elevated titers occurred in 63 per cent of the men and 56 per cent of the women with chronic diseases, but in only 40 per cent of the men and 36 per cent of the women in the "control" population. Patients with coronary heart disease tended to show the highest titers. The suggestion is made that the serum inhibitor under study may reflect, in part, relatively "nonspecific" pathological changes and tissue responses provoked by various biological stresses and is a promising approach to the recognition of cardiovascular disease and related disorders.
Deposition of Flowborne Materials on Vessel Walls
Authors: Rodbard Simon , Johnson Alonza C.
Published: June 2012

An air stream saturated with acetic acid vapor was blown through a tube made of agar which contained sodium hydroxide and phenolphthalein. Where flow was laminar, transfer of acid from the stream to the wall and decoloration of the indicator were of limited degree. Deposition of flowborne material was increased wherever the streamlines were disturbed, as at discontinuities and narrowings. Deposition was minimal slightly beyond the nozzle of the venturi tube, at the site where the momentum of the stream deviates it from the wall. These patterns of deposition by the stream are discussed in terms of their potential effects on the nutrition of the vessel wall, with particular reference to the localization of atheromatous and endocarditic lesions.
An Angiocardiographic Method for Directly Determining Left Ventricular Stroke Volume in Man
Authors: Dodge Harold T. , Hay Robert E. , Sandler Harold
Published: June 2012

A method has been described for directly determining left ventricular stroke volume in man through the use of biplane angiocardiography. Left ventricular stroke volume determined by this method has been compared with stroke volumes determined by the Fick and/or indicator-dilution methods in 14 subjects without arrhythmias or clinical evidence of valvular insufficiency. Stroke volumes determined by these various methods showed close agreement.
Juxtaglomerular Cell Changes in Dogs with Antirenin Titers
Authors: Schmid Herman E. , Graham Leonard A.
Published: June 2012

Renin concentration and juxtaglomerular cell changes, as demonstrated by the Bowie and periodic acid stains, were studied in 11 dogs with partial renal artery constrictions of 1 to 70 months' duration. Three received injections of saline, had renal renin contents averaging 2 Goldblatt Dog Units per Gm. kidney tissue, and had juxtaglomerular cell ratings averaging 1.5, as evaluated on a plus 1 to plus 5 basis. Eight dogs injected with hog renin developed antirenin titers ranging from 1 to 83 units per cc. plasma, had an increase in renal renin content ranging from 3 to 22 Dog Units, and had a juxtaglomerular cell rating ranging from 1.7 to 4.0. The juxtaglomerular cells in the highrenin specimens were markedly hypertrophied and densely packed with cytoplasmic granules. Also, juxtaglomerular cells with granules were found associated with both the afferent and efferent vessels at the vascular pole of the glomerulus. This study supports the concept that the juxtaglomerular cell is the site of renin formation.
Oscillation of Blood Flow and Vascular Resistance During Mayer Waves
Authors: Killip Thomas
Published: June 2012

In cats anesthetized with chloralose, Mayer waves developed following graded hemorrhage and, in some, partial carotid occlusion. The average Mayer wave was 56 mm. Hg in amplitude rising from a base systemic pressure of 70 mm. Hg at a frequency of 3.0 per minute. Rhythmic fluctuation of respiratory depth and frequency paralleled but slightly preceded the blood pressure change. There was no significant variation in heart rate during Mayer waves.

Flow in the abdominal aorta and vena cava varied inversely with systemic pressure. A flow lag of four to six seconds in the vena cava behind that in the aorta during Mayer waves was probably related to circulation time.

Blood flow was measured in muscle, small intestine, skin, and kidney. During the pressure rise of each Mayer wave, blood flow decreased in muscle more than in gut. Cutaneous flow increased moderately. Renal flow varied directly with the arterial pressure. Changes vascular resistance were evaluated by holding perfusion pressure constant and measuring regional blood flow. During Mayer waves, muscle vascular resistance increased 276 per cent, intestinal resistance increased 210 per cent, and cutaneous resistance rose 136 per cent. Renal vascular resistance did not change.

Since Mayer waves are apparently reflexogenic in origin, the data are interpreted as evidence for regional differences in the pattern of central reflex control of the peripheral vascular system.
Chlorides, Potassium and Experimental Cardiac Necroses
Authors: PRIORESCHI P.
Published: June 2012

It is known that the cardiac necroses produced by 9α-fluorocortisol (F-COL) plus Na
2
HPO
4
are prevented by the administration of chlorides or potassium salts. In this paper it is shown that various chlorides not only significantly correct the depletion of myocardial potassium elicited by F-COL + Na
2
HPO
4
but increase the potassium concentration in the heart of normal animals.

In view of these facts and of earlier experiments that have shown that F-COL alone diminishes cardiac potassium without producing necrosis, it is concluded that the depletion of potassium is necessary, but not sufficient, for the development of infarctoid cardiopathy and that the protective electrolytes (chlorides and potassium salts) act through the correction of this abnormality of the potassium level in the heart.
Local Regulation of Effective Blood Flow in Muscle
Authors: HYMAN CHESTER , PALDINO R. L. , ZIMMERMANN EMERY
Published: June 2012

The techniques of macro- and micro-tissue clearance were used to study reactive hyperemia. Clearance of radioactive iodide from gross injection sites in muscles of rabbits and clearance of micro-injected diffusible dye from the exposed, directly observed spinotrapezius of rats gave evidence for an exact quantitative repayment of effective blood flow debt. In both types of preparation a subnormal clearance followed a thermally induced hyperemia as an apparent compensation. The exact quantitative repayment and compensation support the hypothesis that local effective blood flow is in a steady-state relation to the local concentration in tissue fluid of some agent with vasodilating properties.

It is suggested that an extension of this method to studies of vasodilatation induced by drugs or other chemicals might offer an approach to identification of the normal vasodilator, and to physiological proof of its exact nature.
Cardiac Arrhythmias Following Condenser Discharges and Their Dependence Upon Strength of Current and Phases of Cardiac Cycle
Authors: PELEŠKA BOHUMIL , Blažek, Z. , PRábl, M. , Sládková E. , Roth Z.
Published: June 2012

To improve technics for electrical defibrillation of the heart, an apparatus was constructed for the application of a condenser discharge at any selected phase of the cardiac cycle. With this apparatus 2160 discharges were applied through the intact chests of 240 dogs under thiopental anesthesia. The voltage ranged from 0.5 to 6 kv, the condenser capacity from 0.5 to 100 µF, the total energy from 0.06 to 1800 watts. The associated changes in cardiac rhythm were graded from one (no abnormalities) through two (mild, brief extrasystoles), three (more protracted but fully reversible periods of bigeminy, extrasystoles, block, etc.), four (severe but reversible changes lasting several minutes, usually with fall in blood pressure), to five (severe arrhythmias changing into ventricular fibrillation).

The severity of the arrhythmias increased progressively as the voltage was increased, and to a much smaller extent with increases in the total amount of electrical energy. Arrhythmias also were significantly more severe when the shock was delivered during the refractory period (S-T interval) than during the excitable (P interval) stage of the cardiac cycle. Two types of ventricular fibrillation of very different prognosis were revealed. One came on suddenly after low voltage shocks and could easily be terminated by a single adequate defibrillation impulse. The other came on more gradually after high voltages and energies and tended to be irreversible.

Observations thus far made indicate that the severity of the arrhythmia following condenser shocks gives an approximate indication of the severity of pathological changes in the heart. Excessive currents could damage the heart to such an extent that myocardial contractions were weak or absent although electrical activity persisted. Therefore the parameters of condenser discharges used for clinical defibrillation should be such that they will produce only the mildest and briefest arrhythmias.
Effects of Intra-arterial and Intravenous Epinephrine on Disappearance of Nal
131
from Calf Muscle and on Calf Blood Flow
Authors: COFFMAN JAY D.
Published: June 2012

The effects of intra-arterial and intravenous infusions of epinephrine on total blood flow in the calf and on capillary blood flow in calf muscle were determined in human subjects rising venous occlusion plethysmography and radioisotope disappearance rates respectively. The two technics usually demonstrated similar changes with both intravenous and intraarterial routes of administration. Since intravenous epinephrine affected the radioisotope disappearance rates, the hypothesis that epinephrine acts on arteriovenous shunts alone does not appear to apply in these experiments. Intra-arterial epinephrine often produced a sustained increase in blood flow similar to that produced by intravenous epinephrine, indicating that the initial and sustained actions could be explained by local effects of the agent. These studies also add further support for using the radioisotope disappearance rate as a qualitative measure of skeletal muscle blood flow.
Effect of Alterations of Coronary Blood Flow the Oxygen Consumption of the Working Heart
Authors: Ross John , Klocke Francis , Kaiser Gerard , Braunwald Eugene
Published: June 2012

The effects of varying coronary blood flow on the MV

O
O2

of a heart permitted to perform external work at a constant level were determined in 10 experiments. No consistent changes of MV

O
O2

occurred with alterations of coronary blood flow. These results were in contrast with those previously obtained when coronary blood flow was altered in a heart which performed no external work.
Relation Between Coronary Blood Flow and Myocairdial Oxygen Consumption
Authors: Sarnoff S. J. , Gilmore J. P. , Skinner N. S. , Wallace A. G. , Mitchell J. H.
Published: June 2012

Experiments were done in the isolated supported heart preparation to ascertain whether a change in coronary blood flow would induce a change in myocardial O
2
consumption if the activity of the heart (aortic pressure, heart rate and stroke volume) was controlled. Over a wide range of coronary blood flows, the O
2
consumption did not vary under such circumstances. If the coronary flow was restricted to levels which produced an unequivocal deteriration of ventricular performance, a modest decrease in O
2
consumption was sometimes observed.

Reciprocal type experiments were also performed. In these, coronary flow was held constant or nearly so while varying the activity of the heart markedly. Under these circumstances the myocardial O
2
consumption did vary directionally with the amount of ventricular myocardial tension developed insofar as this was indicated by the tension-time index.

Data were also obtained suggesting that ventricular end diastolic fiber length is not of itself a major determinant of myocardial O
2
consumption.
Influence of Coronary Flow upon Oxygen Consumption and Cardiac Performance
Authors: Weisberg Howard , Katz Louis N. , Boyd Eugene
Published: June 2012

The influence of induced changes in coronary flow upon oxygen consumption and cardiac performance were observed in the in situ isovolumic left ventricle. This preparation was established with auxiliary pumps which bypass the dog's right and left heart and by inserting a balloon into the left ventricle so that the latter ejected no blood. Coronary flow was set or varied by a retrograde aortic perfusion pump. Oxygen consumption of the heart was found to be coronary flow dependent or independent, according to the conditions of the experiment. When it is coronary flow dependent there is usually a similar relationship between coronary flow and cardiac performance. In a single preparation, it was sometimes found that cardiac oxygen consumption was coronary flow dependent at lower rates of coronary flow and independent at higher flow rates. Possible explanations and clinical applications are given.
Thebesian Drainage in the Left Heart of the Dog
Authors: MOIR THOMAS W. , DRISCOL THOMAS E. , ECKSTEIN RICHARD W.
Published: June 2012

Direct left heart drainage from the common left coronary artery has been demonstrated in the normally beating dog heart by an isotope dilution technique. The major portion of this drainage has been shown to be through the left circumflex branch of the common left coronary artery. The left anterior atrial artery, a branch of the left circumflex, has in turn been shown to be the major pathway of drainage from the latter. Left heart drainage could not be demonstrated from isotope injections into the left anterior descendens artery, and in only one preparation could such drainage be documented from the septal branch of the common left artery.

The magnitude of left heart Thebesian drainage has been estimated by analysis of time-concentration curves recorded from the aorta. An average of 2% of total common left coronary artery inflow drains directly into the left heart. Although the major drainage is probably into the left atrium, left ventricular drainage has not been excluded.
Indirect Action of Epinephrine on Intraventricular Conduction Time
Authors: MENDEZ CARLOS , ERLIJ DAVID , MOE GORDON K.
Published: June 2012

In dogs with denervated hearts intravenous infusions of epinephrine (1.0 to 3.0 µg/kg/min) caused marked acceleration of the heart rate and a significant reduction of intraventricular conduction time. Equal doses infused into the descending thoracic aorta increased the heart rate only slightly, but exerted undiminished effects upon conduction time.

Evisceration did not modify the intraventricular dromotropic effect of epinephrine so long as the hepatic arterial supply was preserved. Occlusion of the hepatic artery abolished the dromotropic effect of epinephrine without modifying its chronotropic action.

The time course of the dromotropic effect and of the kalemic action of epinephrine was approximately the same.

Intravenous infusions of KCl matching the hyperkalemic effect of epinephrine caused similar dromotropic actions.

Isoproterenol even in high doses (up to 2.0 µg/kg/min) did not decrease intraventricular conduction time and had only a slight hyperkalemic effect.

After the administration of SY28 (1.0 mg/kg) epinephrine caused neither hyperkalemia nor decreased intraventricular conduction time.

It is concluded that in the heart in situ the effect of epinephrine on intraventricular conduction is the result of an indirect action mediated through the liberation of K
+
ions from the liver.
Myocardial Actions of Angiotensin
Authors: KOCH-WESER JAN
Published: June 2012

Synthetic angiotensin a has pronounced inotropic effects on isometrically contracting, isolated papillary muscles of kittens. The response increases with drug concentration over the range from 10
-10
M to 10
-5
M. The mean maximum increase in tension development is 120%. Contractility is raised by angiotensin through an increase in the degree of activation of the contractile elements with no significant change in the duration of their active state. Low concentrations of angiotensin have a greater inotropic action than equimolar concentrations of
l
-norepinephrine; but the maximum inotropic effect obtainable with
l
-norepinephrine is almost twice that of angiotensin.

The inotropic effects of angiotensin on cat atrial muscle are slight, and the drug is inactive on frog ventricular myocardium. It has no effect on the resting length-tension relationship of mammalian atrial or ventricular muscle. The frequency of impulse formation in the SA node is not significantly changed by concentrations of angiotensin up to 10
-5
M. In marked contrast to levarterenol, angiotensin does not cause ectopic impulse formation in atrial or ventricular muscle.

It is suggested that the positive inotropic effect of angiotensin on ventricular myocardium is of importance for the pressor action of the drug in the intact circulation. The increase in myocardial contractility tends to minimize or prevent decreases in cardiac output in the face of increased resistance to cardiac ejection and thus supports the elevation of arterial pressure.
Observations on the Ventricular Dysrhythmia Associated with Atrial Fibrillation in the Dog Heart
Authors: MOE G. K. , ABILDSKOV J. A.
Published: June 2012

The distribution of ventricular cycle lengths and the incidence of "long" cycles were studied during episodes of atrial fibrillation induced by electrical stimulation of the right atrium in exposed dog hearts. It was concluded that the ventricular dysrhythmia can be interpreted in terms of concealed conduction. Long cycles (bracketing one or more responses concealed in the A-V node) tend to favor the occurrence of subsequent long cycles. The probability of occurrence of long cycles is shown to be a function of the duration of the "concealment zone" and of the atrial input frequency.
Depression of Contractile Force of Skeletal Muscle by Intra-arterial Vasodilator Drugs
Authors: HIRVONEN LEO , KOROBKIN MELVIN , SONNENSCHEIN RALPH R. , WRIGHT DAVID L.
Published: June 2012

The intra-arterial administration of vasodilator drugs (acetylcholine, histamine, isoproterenol, adenosine triphosphate, bradykinin, and isoxsuprine hydrochloride) induced reversible depression in the maximal contractile force of the intermittently stimulated gastrocnemius-soleus muscles in the cat. In general, blood flow to the muscles was held constant and perfusion pressure was observed. The agents were effective in depressing the muscle at doses the same as those required to produce dilatation in the resting muscle. Increase in blood flow during infusion could reverse the depression. Atropine, in amounts sufficient to block the hypotensive action of intravenously administered acetylcholine, prevented the muscle depressant action of the latter, while leaving unaffected the action of histamine.

Further experiments, utilizing mainly acetylcholine as the prototype, were performed to test the hypothesis that the depressant effect on the gastrocnemius was closely related to a vascular action of the drugs. Evidence serving both to exclude neuromuscular blockade and to support a vascular effect was adduced from three sets of observations. 1) In vitro tests of blocking action of acetylcholine and histamine on nerve-muscle preparations indicated that any such action would require doses several hundred times greater than those effective in the cat gastrocnemius. 2) Under conditions where dependency of contractile force on blood flow varied, comparison of the effects of acetylcholine to
d
-tubocurarine and decamethonium on the cat gastrocnemius showed that when dependency on flow was reduced the effect of acetylcholine was also, while neuromuscular blockade was affected little. 3) A decrease occurred in the I
131
clearance rate from the gastrocnemius parallel to the reduction in muscle force from acetylcholine, while a much smaller, or delayed, reduction in rate occurred when force was reduced equally by
d
-tuboeurarine.

A redistribution of blood flow within the muscle and associated connective tissue may account for the results.
Production of Chronic Elevation of Left Ventricular End Diastolic Pressure in Dogs: Hemodynamic and Renal Studies
Authors: FRIEDBERG CHARLES K. , LASSER RICHARD P. , ALLEN DOUGLAS F. , FURST STEPHEN E. , GABOR GEORGE E.
Published: June 2012

In an effort to produce a preparation for the study of sodium excretion in chronic left heart failure a graft anastomosis was created between the left subclavian artery and the left atrium in five dogs. This resulted in chronic progressive elevation of left ventricular end diastolic and left atrial pressures. Maximal left ventricular end diastolic pressures ranged between 18 and 30 mm Hg, 10 to 20 weeks postoperatively. There was only a slight rise in right ventricular diastolic pressure and no clinical evidence of right heart failure.

Cardiac outputs remained within normal limits in all animals. Serial electrocardiograms disclosed the development of left ventricular hypertrophy and left ventricular hypertrophy and dilatation were observed at postmortem examination. One dog which survived with a patent shunt for more than a year had right as well as left ventricular hypertrophy but no right heart failure. Glomerular filtration rates, renal plasma flow and excretion of rapidly infused isotonic saline remained unaltered even at the highest levels of left ventricular end diastolic pressure. Although the development of left and eventually right ventricular hypertrophy, the chronic and progressive elevation of left ventricular end diastolic, mean left atrial and pulmonary arterial pressure, with only slight elevation of right ventricular end diastolic pressure, were regarded as characteristic features of isolated left ventricular failure, the propriety of this term may be questioned in view of the unaltered cardiac output and renal hemodynamics. But the observations do indicate that marked elevation of left ventricular end diastolic and presumably pulmonary venocapillary pressure, such as occur in left heart failure, do not impair renal excretion of sodium.
Renal Baroreceptor Control of Acute Renin Release in Normotensive, Nephrogenic and Neurogenic Hypertensive Dogs
Authors: SKINNER SANDFORD L. , MCCUBBIN JAMES W. , PAGE IRVINE H.
Published: June 2012

Graded reductions in mean renal perfusion pressure cause kidneys of normotensive, renal, and neurogenic hypertensive dogs to release renin. In anesthetized normal dogs with mean resting pressures of 110 to 150 mm Hg, increased renin secretion occurred at renal perfusion pressures of 90 to 120 mm Hg. In dogs hypertensive from constriction of a renal artery, pressure beyond the constriction was within the normal range, and lowering of renal perfusion pressure caused release in the same range as in normal dogs. In dogs with neurogenic hypertension due to section of the carotid sinus and aortic depressor nerves, return was released at perfusion pressures within, or only slightly above, the normal range.

In sharp contrast with these three groups, renin was released in dogs with hypertension due to perinephritis at mean pressures of 140 to 165 mm Hg when lowered from resting levels of 180 to 220 mm Hg. This different range could depend either upon reduced intrarenal pressure which mimicks the effects of a renal artery clamp or upon a change in range of response of the renal baroreceptor due to some more direct effect of the perinephritic hull. No evidence was found that the renal baroreceptor control of renin secretion is nonfunctional in dogs with renal hypertension.
Use of Radioiodinated Fatty Acid for Photoscans of the Heart
Authors: EVANS JOHN R. , GUNTON RAMSAY W. , BAKER ROBERT G. , BEANLANDS DONALD S. , SPEARS JOHN C.
Published: June 2012

Radioiodinated fatty acid bound to albumin (RIFA) was given by intravenous injection to dogs and moribund human subjects in order to label heart muscle.

Photoscans of the thorax of dogs given RIFA revealed concentration of radioactivity in the ventricular region of the heart due to incorporation of the labeled fatty acid into myocardial triglyceride and phospholipid.

Photoscans of the thorax following intravenous injection of radioiodinated serum albumin or NaI
131
showed a different density pattern in the region of the heart due to radioactivity in blood within the cardiac chambers.

Areas of myocardial infarction were detected in photoscans of the thorax in 11 of 14 dogs in which one coronary artery was ligated. At necropsy the concentration of radioactivity was much higher in healthy myocardium than in infarcted muscle. The same distribution of radioactivity was observed in hearts from three human subjects with myocardial infarction given RIFA shortly before death. It is proposed that areas of myocardial infarction might be demonstrated during life by photoscans of the thorax following intravenous injection of RIFA.
Children at High Altitude: Pulmonary and Renal Abnormalities
Authors: NAEYE RICHARD L.
Published: June 2012

Changes in pulmonary arteries and renal glomeruli were assessed in children born and resident at high altitude (Leadville, Colorado). The hypoxia appears to arrest normal neonatal decrease of pulmonary arterial smooth muscle in some of these children. No abnormalities were found in pulmonary veins or capillaries. A quantitative study also demonstrated enlargement of renal glomeruli in the hypoxic children after the first month of life, apparently due to a proliferation of normal glomerular elements.
Induced Pressure Gradients Across Infundibular Zone of Right Ventricle in Normal Dogs
Authors: TOBIN JOHN R. , BLUNDELL PETER E. , GOODRICH RALPH G. , SWAN H. J. C.
Published: June 2012

In these experiments we have demonstrated that:

1. Right ventricular outflow-tract pressure gradients of significance can be induced in normal dogs by a sympathomimetic amine which increases the rate and force of ventricular contraction.

2. Such outflow-tract pressure gradients are magnified by the addition of other inotropic drugs, such as acetyl strophanthidin and calcium chloride.

3. These outflow-tract pressure gradients are not the result of an increase in the volume and rate of blood flow but are due to forceful contraction of the infundibulum.
Metabolism of Perfused C
14
-Labeled Nucleosides and Bases by the Isolated Heart
Authors: TSUBOI K. K. , BUCKLEY N. M.
Published: June 2012

The cardiac metabolism of C
14
-labeled nucleosides and bases was investigated in isolated rabbit hearts perfused with a glucose-electrolyte medium. Records of contractile force, heart rate and coronary drainage were taken at intervals before, during, and after perfusion with a labeled compound. Contractile force was increased in the presence of inosine, uridine, guanosine, and hypoxanthine; and decreased in the presence of adenine. Determination of radioactivity of aliquots of perfusate during C
14
perfusion and washout periods showed generally constant uptake of the labeled compounds by the hearts, after an initial dilution by tissue water, and efficient washout of extracellular label before preparing myocardial extracts.

Recirculation of inosine-C
14
was accompanied by incorporation of radioactivity into cardiac nucleotides, chiefly adenine nucleotides but also inosinic acid (IMP) and guanine nucleotides. Labeled hypoxanthine was recovered from both heart and perfusate. Recirculation of uridine-C
14
was accompanied by incorporation of radioactivity into cardiac uridine nucleotides, and the appearance of labeled uracil in the perfusate. In both groups of experiments, the ratio of labeled base to nucleoside in cardiac extracts exceeded the ratio in perfusates, indicating unequal cellular retention of base and nucleoside.

Perfusion with guanosine-C
14
led to limited incorporation of C
14
into guanine nucleotides without interconversion to other cardiac nucleotides.

Recirculation of C
14
-labeled hypoxanthine or adenine was accompanied by incorporation of radioactivity into cardiac purine nucleotides. Equivalent label distribution was found among adenosine monophosphate, adenosine diphosphate, and adenosine triphosphate, indicating intracellular equilibrium among these compounds. Conversion of labeled adenine to hypoxanthine occurred in the perfusate of the adenine-C
14
experiments.

The cardiac metabolism of the perfused nucleosides and bases followed generally predictable sequences, and did not suggest a mechanism for the marked inotropic activity of these compounds.
Permeability of the Alveolar Membrane to Solutes
Authors: TAYLOR AUBREY E. , GUYTON ARTHUR C. , BISHOP VERNON S.
Published: June 2012

The lower lobe of the left lung of 54 dogs was isolated and perfused with a dextran-Tyrode's solution. The alveoli were filled with Tyrode's solution, and permeability coefficients were measured for diffusion of several substances across the alveolar membrane. The permeability coefficients of the pulmonary membrane for K
42
, urea, Na
24
, glucose, D
2
O, and dinitrophenal(DNP) were 56.5 ± 3.5, 22.9±9.2, 7.5±2.1, 3.1±0.7, 400, and 400x10
-7
cm/sec, respectively. The effect of varying the flow rate on the permeability coefficient of Na
24
was investigated, and the data failed to show any significant correlation between the flow limits of 3.8 to 12. 8 cm/min/g lung tissue. The effect of two different procedures for filling the alveoli with fluid on the permeability coefficients was also investigated and no difference could be discerned in the results. The data support the thesis that the alveolar membrane has permeability characteristics similar to those of the usual cell membrane. The interstitial fluid volume of the lung (extravascular sodium space) was measured and yielded a value in normal lungs of 0.250 ± 0.129 cc/g lung tissiue. In three edematous lungs, this space averaged three times the normal value.
Effect of Coronary Artery Embolization on Ventricular Volumes
Authors: WONG MAYLENE , ESCOBAR EDGARDO E. , MARTINEZ GILBERTO , RAPAPORT ELLIOT
Published: June 2012

The progressive changes in ventricular volumes and pressures created by repeated coronary artery embolizations with lycopodium spores were studied in fifteen intact dogs. In eight of the animals SV increased over control values following the initial embolization. Subsequent embolizations produced a pronounced decrease in SV and SW, an enlarged EDV, and a high ESV/EDV ratio. Left ventricular systolic pressure fell as EDP rose. The progressive increase observed in the ESV/EDV ratio between successive embolizations was the most sensitive functional expression of the deteriorating myocardial performance.
Circulatory Response to Release of Chronic Pulmonary Artery Constriction
Authors: TOBIN JOHN R. , RASTELLI G. C. , BLUNDELL PETER E. , SWAN H. J. C.
Published: June 2012

The imposition of a chronic work load (pulmonary artery constriction) on the right ventricle increases ventricular muscle mass. This is associated with increased ventricular stroke work when the animal is standing awake, during infusions of norepinephrine, and under conditions of exercise (running on a horizontal treadmill). Studies two weeks after release of chronic pulmonary artery constriction reveal stroke volume and cardiac output are increased during standing at rest, during norepinephrine infusion, and during exercise. Studies eight weeks after removal of pulmonary artery bands show that stroke volume and cardiac output are approaching the normal range. Right ventricular hypertrophy and right ventricular stroke work decline progressively and apparently in parallel in the weeks following release of chronic pulmonary artery constriction.

The stroke work capacity of the ventricle seems related to the presence of right ventricular hypertrophy. With a reduction in outflow tract resistance, the stroke volume for a given set of circumstances is markedly increased. From this standpoint, the work capacity of the right ventricle may be taken as a determinant of stroke volume and cardiac output.

Decrease of systemic vascular resistance and relative insensitivity of systemic vasoreceptors to norepinephrine were observed after the release of chronic pulmonary artery constriction. These phenomena have roles in the production of the observed hyperdynamic circulatory state, but their contributions to its genesis are secondary to the major role of the hypertrophied right ventricle.
Indicator Dispersal by Convection and Diffusion in Fluid Flow Through a Tube
Authors: RICH DAVID C. , GOODMAN JOHN W.
Published: June 2012

A tube is filled with water containing indicator and then the indicator is washed out by laminar flow of indicator-free water. Given a measurement of mean volume concentration of indicator in the effluent as a function of time, a theoretical expression is derived for the pattern of indicator delivery in the case where diffusion is superimposed on convective transport. Satisfactory experimental verification of the theoretical expressions was obtained.
Human Cardiac Myosin: Electron Microscopic Observations
Authors: CARNEY JOHN A. , BROWN ARNOLD L.
Published: June 2012

Solutions of human cardiac myosin contain macromolecules which were visualized in the electron microscope by the shadow-casting technic. The dominant particle was observed to be rod-shaped, to have a globular expansion at one end, and to have a mean length of about 1500 Å. The molecule of human cardiac myosin was found to be morphologically similar to myosin molecules from canine cardiac muscle and rabbit skeletal muscle.
Effect of Variations of Plasma Sodium Concentration on the Adrenal Response to Angiotensin II
Authors: BLAIR-WEST JOHN R. , COGHLAN JOHN P. , DENTON DEREK A. , GODING JAMES R. , WINTOUR MARELYN , WRIGHT R. DOUGLAS
Published: June 2012

The secretion rate of aldosterone was increased by infusion of valine-5-angiotensin II into the adrenal arterial blood supply of sheep. The dimensions of the increase in aldosterone output were inversely related to the control plasma concentration. This high aldosterone secretion was reduced substantially by concurrent adrenal infusion of concentrated NaCl solution which increased plasma sodium concentration by approximately 10 meq/liter. The reduction of aldosterone secretion occurred within 20 minutes. Angiotensin II infusion did not increase the secretion rates of cortisol or corticosterone.

The significance of the finding that environmental sodium concentration has different effects on the aldosterone-stimulating action and the pressor action of angiotensin II is discussed.