Constricted State Research Articles

Partitioning of pulmonary resistance during constriction in the dog: effects of volume history.

We assessed the relative changes in airways and lung tissue with bronchoconstriction, and the changes in each during and following a deep inhalation (DI). We partitioned pulmonary resistance (RL) into airway (Raw) and tissue (Vtis) components using alveolar capsules in 10 anesthetized, paralyzed, and open-chested dogs ventilated sinusoidally with 350-ml breaths at 1 Hz. We made measurements before and during bronchoconstriction induced by vagal stimulation or inhalation of histamine or prostaglandin F2 alpha (PGF2 alpha), each of which decreased dynamic compliance by approximately 40%. With histamine and PGF2 alpha the rise in RL was predominantly due to Vtis. With vagal stimulation there was a relatively greater increase in Raw than Vtis. At higher lung volumes, Vtis increases offset falls in Raw, producing higher RL at these volumes before and during constriction with PGF2 alpha and histamine. During constriction with vagal stimulation, the fall in Raw with inflation overrode the rise in Vtis, resulting in a lower RL at the higher compared with the lower lung volume. The changes seen after a DI in the control and constricted states were due to alterations in tissue properties, both viscous and elastic. However, the relative hysteresis of the airways and parenchyma were equal, since Raw, our index of airway size, was unchanged after a DI.

Evaluation of concentration-response relationships for histamine and sulfuric acid aerosols in unanesthetized guinea pigs for their effects on ventilatory response to CO 2

Through the addition of aerosols to 10% CO 2 mixtures, acute respiratory responses can be detected in unanesthetized guinea pigs. This conclusion was supported by results from a previous study conducted in our laboratory in which animals were exposed to nebulized histamine or sulfuric acid while placed in a whole-body plethysmograph. In that study, only one concentration of each agent was examined. The present data were collected over a wider range of histamine and sulfuric acid exposure concentrations and the results served to reinforce the previous conclusion regarding the ease in detecting acute responses with this approach. Again, inspiratory volume ( VI) and pressure changes (Δ P), proportional to inspired volume, were measured continuously and significant decreases in these parameters occurred during aerosol challenges. In addition, respiratory frequency ( f) was evaluated during all exposures but few changes in frequency were observed other than the increases induced by 10% CO 2 alone. Measurements of VI and Δ P indicated similar levels of response to the tested aerosols, except during intense bronchoconstriction evoked by higher concentrations of histamine. In such constricted states, VI was a more sensitive indicator. Concentration-response relationships for histamine and sulfuric acid using VI measurements were comparable to those of other investigators who measured airflow resistance. Therefore, the new method offers many advantages over previous methods through its noninvasive and simple features yet there is comparable sensitivity to detect acute responses, as demonstrated by this study.

Role of mitochondria in ischemic acute renal failure.

Ischemic ARF is characterized by progressive mitochondrial accumulation of Ca++ which is inversely correlated with the level of oxidative phosphorylation. At least two possibilities exist which would be compatible with these data 1) depressed respiration leads to Ca++ accumulation or 2) increased mitochondrial Ca++ leads to reduced mitochondrial respiration. We favor the latter hypothesis for the reasons outlined above; furthermore, this conclusion is supported by the observations of Lehninger, made some 20 years ago: first, that either oxidative phosphorylation or mitochondrial Ca++ accumulation can be accomplished by intact mitochondria but that these events cannot occur simultaneously and second, that Ca++ accumulation takes precedence over oxidative phosphorylation. Our observation made during post-ischemic reflow that mitochondrial Ca++ accumulation occurs to a significant degree, strongly suggest a potential role for mitochondrial Ca++ overload in the pathogenesis of ARF. Nevertheless, this is not an irreversible pathogenetic process. Clearly, impermeant solutes, vasodilators and Ca++ membrane blockers will alter the natural history of this injury and prevent the severity of the functional defect. A common mechanism of action may involve direct or indirect modification of cellular Ca++ overload in renal vascular and epithelial tissue. The vascular smooth muscle may then revert to a less constricted state with a subsequent more rapid recovery of renal blood flow and that the renal epithelial cell death may be minimized thereby reducing tubular obstruction.

Effect of pentobarbital anesthesia and surgery on the control of arterial pressure and mesenteric resistance in cats: role of vasopressin and angiotensin.

We compared the effects of pentobarbital-induced anesthesia and major surgery (laparotomy) on the mesenteric resistance vessels and arterial pressure of cats. Intravenous infusion of sodium pentobarbital (30 mg/kg over 30--60 min) into conscious and unrestrained cats caused only a small increase in superior mesenteric arterial conductance and a small fall in femoral arterial pressure. In contrast to the effects of pentobarbital, major surgery caused marked mesenteric vasoconstrictor and pressor responses. Under these conditions, acute hypophysectomy and infusion of [Sar1, Ala8]angiotension II (saralasin) caused mesenteric conductance and arterial pressure to return towards presurgery control values. The results suggest that the high arterial pressure and constricted state of the mesenteric bed seen in acute experiments appears to be related to surgical stress rather than pentobarbital-induced anesthesia and that both the vasopressin system and the renin-angiotensin system appear to play important roles in the control of arterial pressure and the mesenteric resistance vessels under these conditions.

Rhythmic activity of cat pial vessels in vivo.

Rhythmic activity was observed in over 100 pial vessels in 58 cats with a photometric technique through a cranial window. Diameter oscillations with a frequency of mostly 5/min were present at normal mean arterial pressure (MAP) in about half of the animals. When spontaneous activity was absent the same type of oscillations could be provoked by varying MAP, mostly by lowering it to a level of around 60 mm Hg. If a rhythmic activity was present, it could be abolished by increasing and decreasing MAP. Likewise, rhythmic activity ceased during strong vasodilatation caused by hypercapnia, hypoxia, Ca antagonists or other vasoactive drugs. Rhythmic activity also decreased in amplitude or disappeared with vasoconstriction accompanied by a stable MAP. Rhythmic activity of pial vessels thus seemed to occur within an as yet unspecified range of vessel wall tensions mediated via intraluminal pressure and a state of constriction or dilatation. This rhythmic activity was not primarily influenced by sympathetic stimulation, alpha-sympathetic blockade, hyper- or hypocapnia, hypo- or hyperoxygenation. Moreover, the vascular activity fits well with the description of rhythmic smooth muscle activity in other vascular beds and organs in vitro and in vivo, ascribed to myogenic regulatory processes. Therefore, it is suggested that the rhythmic activity of pial vessels might be an expression of myogenic blood flow regulatory activity in the brain.

Action of drugs on the human colonic preparations of Hirschsprung's disease

Strips from distended (ganglionic) and constricted (aganglionic) segments of bowel from patients with Hirschsprung's disease were examined in vitro for their responses to acetylcholine, nicotine, dimethylphenylpiperazinium, 5-hydroxytryptamine (5-HT) and histamine. Acetylcholine contracted both the distended and constricted isolated colonic preparations. Nicotine and dimethylphenylpiperazinium relaxed, contracted or produced biphasic effects in the distended, while they had no effect or contracted the constricted isolated colonic preparations. The tissue of distended segments responded to small concentrations of 5-HT by relaxation, while it had no effect, or in one fifth of the experiments relaxed, the constricted isolated colonic preparations. The isolated strips of distended and constricted colonic segments responded by contractions to high concentrations of 5-HT. The preparations of distended and constricted segments responded to histamine with contraction, relaxation or biphasic effects. However, when histamine produced relaxation or a biphasic effect in preparations of distended segments, the relaxation was obtained only in about one half of the experiments in strips of constricted segments. It is concluded that an inadequate inhibitory influence is responsible for the disordered peristalsis and that it might account for the constricted state of the affected bowel.

Falling-out: A diagnostic and treatment problem viewed from a transcultural perspective

The author describes a seizure-like disorder called falling-out by black Americans, blackingout by Bahamians and indisposition by Haitians in Miami. Falling-out is used as a general label for all three variants of what appear to be equivalent syndromes. The state is one in which the individual collapses without warning, occasionally with some degree of salivation but without convulsions, tonguebiting, bowel or bladder incontinence. The person afflicted usually hears and understands what is happening but is powerless to move. Even though his eyes may be open, the individual tends not to see. The condition does not meet the criteria for epilepsy or hysteria: although persons who experience it are sometimes misdiagnosed as epileptics or hysterics. Prevalence indicators are reviewed. The conclusion is drawn that the condition is a significant health problem for black Americans and Bahamians and probably for Haitians in Miami. Preliminary observations on contexts of occurrence are provided. Difficulties of diagnosis are described from both emic (cultural/ “within”) and etic (orthodox/“without”) positions. The challenge to the orthodox health care system is considered. In its chronic form falling-out is viewed as being psychogenic in origin and a candidate for classification as a “culture-bound” syndrome. The predominant process involved appears to be dissociation in the form of a constricted state of consciousness. The psychophysiological state should be viewed as a means of ego defense and an adaptive response. Its effectiveness should be judged by the degree of psychological and social reintegration achieved following the episodes themselves. Reliance upon dissociation as a means of coping with crisis must be understood within the framework of a view of the world as threatening, unpredictable and potentially harmful to an “acted-upon” self. Such episodes must be judged for their ability to relieve anxiety and also for the degree to which they are successful in bringing about a state of adaptedness at a more effective, equal or reduced level of functioning. The orthodox health institution carries responsibility for reducing morbidity from falling-out and for devising therapeutic approaches which take into consideration both emic and etic etiological and therapeutic assumptions. We do not yet know how to do this, but several therapeutic approaches are mentioned which might be considered. They require both transdisciplinary (social science/medicine) and transcultural (emic/etic) perspectives rather than unicultural ones. Research considerations are briefly discussed.

Hypophysectomy and saralasin on mesenteric vasoconstrictor response to vasopressin

The dose-response relationship of the mesenteric resistance vessels to vasopressin was studied in anesthetized laparotomized cats before and after hypophysectomy and again during the plateau phase of the response to a prolonged infusion of [Sar1-Ala8] angiotensin II (saralasin), a competitive antagonist of angiotensin II. Hypophysectomy and saralasin each caused an increase in superior mesenteric arterial conductance. Before hypophysectomy infusion of 0.5 mU/(min.kg) of vasopressin caused mesenteric conductance to decrease from 0.168 to 0.156 ml/(min.kg.mmHg), a change of only 0.012 units. After hypophysectomy, the same dose reduced conductance from 0.227 to 0.179 mU/(min.kg.mmHg), a change of 0.048 units. During the plateau phase of the response to saralasin, 0.5 mU/(min.kg) of vasopressin reduced conductance from 0.281 to 0.201 ml/(min.kg.mmHg), a change of 0.079 units. Hypophysectomy and saralasin had little effect on the mesenteric vasoconstrictor response to high doses of vasopressin (2.0-10 mU/(min.kg). The ineffectiveness of low doses of vasopressin on the mesenteric resistance vessels of the intact anesthetized, surgically stressed animal may be due in part to the already constricted state of the bed caused by endogenous vasopressin and angiotensin and in part due to an opposing vasodilator influence, the reflex withdrawal of the vasoconstrictor effect of endogenous vasopressin.

The effects of high hydrostatic pressure on microfilaments and microtubules in Xenopus laevis

Xenopus laevis embryos of stages 14-20 were subjected, for periods of 5-330 min, to hydrostatic pressures ranging from 500 to 10 000 psi. The specimens were fixed under corresponding pressures and their neuroepithelium was studied under light and electron microscopy. A pressure of 3000 psi, maintained for as long as 180 min, did not inhibit neurulation though it induced slight deformities of the neuroepithelium. A pressure of 4000 psi, applied for 180 min, disrupted the apical ring of microfilaments and blocked neurulation. The cells lost their dissymmetry. The effect was reversible. Lengthening the duration of treatment to 330 min caused the neuroepithelial cells to loose their microtubules and to become round. This situation was not reversible. Our results indicated that microfilaments are more sensitive than microtubules, that both organelles became increasingly sensitive as the exerted pressure was increased and that microtubules of older embryos exhibited a better resistance. Finally, we showed a correlation between the presence of microfilaments and the constricted state of the cellular apices and a relationship between the presence of microtubules and cell elongation.

The action of histamine on pulmonary vessels of cats and rats.

1. The actions of histamine on pulmonary vascular smooth muscle have been studied in isolated cat and rat lungs perfused with blood, lobes of cat lung perfused in vivo and isolated strips of rat, cat and rabbit pulmonary artery. 2. In all the lung preparations histamine caused both dilatation and constriction. In the rat strips it caused both contraction and relaxation. Dilatation was only well shown when the vessels were in a prior constricted state. In any one lung dilatation occurred with smaller doses than constriction. 3. Histamine caused both increases and decreases in pulmonary artery pressure in collapsed lungs. In this condition these effects are unlikely to have been a consequence of changes in airway pressure. 4. From forward and reverse perfusions of lungs in the waterfall state, where changes in postalveolar vessels do not affect pulmonary artery pressure, it appeared that histamine caused both dilatation and constriction on both sides of the point of collapse caused by alveolar pressure. 5. Plots of the relationship between left atrial and pulmonary artery pressure (at constant alveolar pressure and blood flow) showed that histamine caused both increases and decreases in pulmonary vascular resistance and sometimes also increased the "Starling resistor" properties of lung vessels. 6. In plethysmograph experiments histamine caused moderate dilatation and constriction without affecting lung volume but strong vasoconstriction was accompanied by increases in lung volume.

Maximal expiratory flow and lung volume changes associated with exercise-induced asthma in children and the effect of breathing a low-density gas mixture.

1. Lung volumes and maximum expiratory flow volume (MEFV) curves were measured before and after exercise and after a bronchodilator in eight asthmatic children. 2. Exercise produced significant changes in all volumes and flow rates measured, but the most sensitive measurement was of flow rate at an absolute volume in the terminal portion of the forced vital capacity. Of the more simply obtained measurements maximal flow at 50% of the exhaled vital capacity was the most sensitive, but reductions in forced expiratory volume at 1 s and peak flow rate were almost as marked. 3. The marked reductions in flow rates at low lung volumes after exercise were accompanied by large increases in residual volume and a reduction in the slope of the MEFV curve. These changes suggest functional closure of some lung units and an increase in the time-constant of emptying of other units. 4. The response of flow to breathing helium—oxygen (79:21, v/v) was assessed in the dilated state (before exercise or after bronchodilator) and the constricted state (after exercise) in five of the subjects. 5. An increase in density-dependence of flow rates at all lung volumes during constriction is evidence that, despite the reduction in flow rates, convective acceleration and turbulent flow constitute a greater proportion of the total upstream resistance after exercise than before exercise. The implication is that the cross-sectional area at equal pressure points (EPP) is smaller after exercise than before exercise. This could result from either bronchoconstriction with no change in the location of EPP, or from progression of the EPP further upstream to a region where loss of airways or reduction in their diameter has rendered the total cross-sectional area considerably smaller than under normal circumstances.

Myofilaments of the pupillary muscles of the iris fixed in situ

The sphincter muscle of the rat iris was studied by perfusion fixation in the constricted and dilated state. Both thick filaments (220–230 ) and thin filaments (70–80 ) were observed in sphincter muscle from both the constricted and dilated pupil if the tissue was well fixed by perfusion. Failure to achieve good fixation resulted in the observance of only 70–80 filaments. It was determined that good perfusion was more dependent on the extent of prefixation perfusion than on the concentration of the fixative or the type of fixative used. Good fixation and the demonstration of thick filaments were achieved by perfusion with 0.1% OsO4 or with concentrations of glutaraldehyde of 0.5–12.0% if the animal was thoroughly perfused with 150–200 ml of a salt solution prior to the fixation. The quality of the salt solution had little effect on the results since 0.9% NaCl could be successfully substituted for Krebs-Ringer solution.

The Effect of Electrode Material on the Initial Expansion of an Arc in Vacuum

A theory of electrode controlled arc expansion is developed in terms of the finite time it takes for the current path in the electrodes, to change from the highly constricted state during the molten bridge stage, to the less constricted state of the fully developed arc. This theory gives satisfactory agreement for vacuum arc expansion rates when freshly prepared electrodes are used. The expansion rates for the arc after the electrodes have been arced once, however, are much slower. By considering small changes in the work function of the surfaces of the cathode we give a qualitative explanation of this slower expansion.

EFFECTS OF DESTRUCTION OF INTRAMURAL GANGLION CELLS ON THE MOTILITY OF THE ILEOCECOCOLIC REGION

1) Utilizing the complete-anemia method devised by HUKUHARA et al., the intramural ganglion cells of the dog ileocecocolic region were destroyed.2) The animal could not be fed because it vomited every time it took food. The animal survived29days by i. v. infusion of the nutrient solution.3) The roentgenological examination revealed that the segment affected was in a state of persistent constriction. The histological examination revealed that intramural ganglion cells disappeared in the middle portion of the constricted segment, and that they showed signs of degeneration in the region 0.5-1.0cm close to both ends of the segment.

Peripheral vascular tonus and reactivity. Independent variables.

During our experiences with total body perfusion, using extracorporeal heart-lung bypass, we noted unexplained variations in the response of peripheral vascular resistance to standard test doses of vasomotor drugs. Further experimentation was performed using the mature dog and our heart-lung bypass apparatus designed previously for the study of the role of the pulse in maintenance of the systemic circulation. 12 The arterial inflow to the animal was a continuous, pulseless, gravity perfusion at an essentially constant blood pressure. The present experiments are predicated on the following concepts: (1) Peripheral vascular tone is defined as the effective state of constriction or dilation of the peripheral vascular tree during a given steady state perfusion; it can be described by the ratio of the measured blood pressure and flow. (2) Peripheral vascular reactivity is defined as the change in the pressure-flow ratio following the introduction of some stimulus, such as a vasomotor drug.

Effects of destruction of intramural ganglion cells on colon motility: possible genesis of congenital megacolon.

1. In the dog, a segment of colon corresponding to the recto-sigmoid region of man, was kept in a temporary state of anemia by perfusing the blood vessels of the loop with TYRODE solution for 4 hours, blood circulation of the loop being resumed thereafter.2. Periodic roentgenologic examinations between 14 and 350 days after operation, revealed that the perfused loop remained persistently in a state of constriction with marked or with slight dilatation of the colon proximal to that site. We feel, that the picture of congenital megacolon may thus be produced experimentally.3. The intramural ganglion cells in the constricted loop had degenerated completely.

Rheoplethysmographic studies of digital venous tone and venous activity.

Abstract It has been shown that partial obstruction to digital venous outflow resulted in slight increase in tone and constriction of the precapillary digital vessels and from slight to marked increase in postcapillary vascular tone and constriction. The digital veins were among the postcapillary vessels. The mechanism for the increase in venomotor tone as well as the tone of the other vessels remains unknown. Four types of volume-time course curves for the initial pulse cycles after inflation of the digital collecting cuff were described. These included the patterns for (1) the resting, relaxed state of the digital vessels, (2) the dilated state, (3) the constricted state (Types A and B), and (4) the obstruction to digital flow. These curves have significant rheoplethysmographic, physiologic, and pathologic connotations. Noradrenalin was found to constrict the postcapillary digital vessels, including the veins, but the veins were not constricted as much as the precapillary vessels for the doses used. The orienting reflex, psychogenic and neurogenic reflexes, and deep inspiration were found to produce constriction of the postcapillary vessels, including the digital veins, as well as the precapillary vessels. It was found rheoplethysmographically that the pre- and postcapillary vessels constrict and/or dilate discordantly or disproportionately in the same manner described for the afferent and efferent arterioles of the kidney. This phenomenon probably exists for other organs as well. The phenomenon is most likely concerned with the regulation of water and solute loss into, and absorption from, the intercellular spaces, and with interstitial fluid circulation and lymph flow in healthy and diseased states. The value of digital rheoplethysmography in the study of the peripheral circulation was further emphasized by these observations.

Treatment and Nursing Care of Hypertension

vised-the Regitine test, the benzodioxane test, and the histamine test -to indicate a 'umor. Regitine and benzodioxane neutralize the hypertens ve effects of the epinephrine and norepincphrine which are produced by the tumor. Hence, a significant lowering of blood pressure following the injection of these agents suggests that the hypertension is due to the presence of a pheochromocytoma. Another rare, but surgically curable, form of hypertension is that associated with constriction of the aorta. In this instance a congenital defect causes a narrowing of the descending thoracic aorta. In the majority of cases of hypertension, however, the cause is unknown and this condition has been called essential Regardless of the cause of the hypertension, the end results will be the same essentially and will depend, in large measure, on the degree and duration of the hypertension. The persistent state of constriction results in marked thickening of the walls of the arterioles and if the hypertension is severe enough there is actual necrosis of these vessel walls. The development of athcrcsclerosis of the larger arteries, particularly the coronary, renal, and cerebral vessels, is accelerated. The sclerotic changes in the renal arteries and the arterioles may lead to gradual impairment of renal function; in the brain they may produce cerebral thromboses and hemorrhages; in the heart they may lead to a coronary occlusion with resulting myocardial infarction. The left ventricle in patients who have hypertension works harder than it does in people with normotension since it has to maintail. a normal output of blood against a high head of pressure. As a result it will dilate, hypertrophy, and may eventually fail to function. In many patients the hypertension remains very mild or the blood pressure may be elevated only at times of stress; at other times, such as in sleep, it may be quite normal. In general, and particularly in young male patients, the hypertension tends to progress and to become fixed. One way of classifying hypertension according to the grade of severity is by ophthalmoscopic examination of the optic fundi. Various degrees of narrowing of the retinal arterioles are listed as Grade I and II changes. Hemorrhages and exudates in the retina are classified as a Grade III change and always signify a severe degree of hypertension. The presence of edema of the optic nerve head (papilledema) represents a Grade IV

La dynamique circulatoire au cours de la persistance du canal artériel et le problème de l’hypertension artérielle pulmonaire

Clinical and hemodynamic studies of 7 cases of patent ductus arteriosus gave us the following results: (1) The pulmonary blood pressures are generally normal in cases of patent ductus arteriosus. (2) However, some patients presenting a patent ductus arteriosus may have a very marked pulmonary hypertension: this hypertension does not depend on the shunt and is very probably primary; it might result from a state of constriction in Ihe small pulmonary vessels; this hypertension provokes in Ihe end irreversible vascular alterations. (3) Patients with a patent ductus arteriosus associated with a pulmonary hypertension present a particular clinical picture: the diastolic component of their murmur is absent; cardiopathy is badly tolerated by them; during an exercise test, they present a deficiency in oxygen of their arterial blood and a decrease of the ratio ot oxygen consumed per liter of ventilation; in some cases there may be cyanosis and clubbing. (4) There is no electrocardiographic pattern characteristic ot the patent ductus arteriosus; very different aspects can be observed. In opposition to common opinions, tracings with a right axis deviation are no exception. Anyway, there is no constant relation between the importance of the shunt and the electric axis deviation. © 1952 S. Karger AG, Basel.

Effect of Potassium Chloride on the Normal and Denervated Iris

Camp and Higgins have called attention to the similarity of the actions of epinephrin and the potassium salts on various organs and have advanced the hypothesis that epinephrin acts by liberating potassium; no reference was made by them to the action of potassium on the iris. Experiments were carried out using intact and excised bulbi of frogs and intact normal and denervated eyes of living rabbits. Forty-four excised frog bulbi placed in 0.6% KCl, and observed 90 to 150 minutes, resulted in 32 constrictions, 1 dilation, and 11 showing no change. Control eyes placed in 0.6% NaCl gave similar results. In another sseries of experiments, the cerebra of frogs were pithed or lightly crushed and 0.25 to 1 cc 0.6% KCl injected intracardially or into the aorta. Of 66 eyes observed, 18 showed no change; 41 constricted and 7 dilated. The dilatations were slight or moderate, the maximum being 1 mm. Control injections of 0.6% NaCl produced constriction or no change. Large doses of KCl, i. e., 1 to 2 cc of a 4.0% solution injected intraärterially into 12 frogs produced constriction in all cases. During the constricted state 0.25 to 0.5 cc epinephrin 1:10,000 was injected intracardially or into the aorta; in all cases the pupils markedly dilated. Seventeen excised bulbi from frogs previously injected with 1-2 cc 1.0% KCl showed no greater sensitivity to dilute solution of epinephrin than 18 control eyes from frogs injected with similar amounts of NaCl. Three series of experiments were carried out on living rabbits having one iris sympathectomized, by removing the superior cervical ganglion. In the first series, 11 experiments on 6 rabbits, 1.0 cc of a 4.1% solution of NaCl was injected subconjunctivally in both eyes. There were no changes except for a few transitory constrictions.