Responses of blood vessels in the resting hand and forearm to various stimuli

With the development of accurate plethysmographic methods, considerable knowledge has been gained regarding blood flow in, and vasomotor reactions of, blood vessels in the hand. However, it has been demonstrated that alterations in blood flow in the hand apparently do not parallel vascular responses elsewhere in the body. For example, Grant and Pearson¹ and, more recently, Kunkel, Stead, and Weiss² have reported that adrenalin, although it produces a marked decrease in blood flow through the hand, causes an increase in flow through the forearm. Likewise, Abramson, Zazeela, and Oppenheimer³ have observed that smoking causes a significant reduction in flow in the hand and practically no change in the forearm. Since blood flow measurements in the hand have been used qualitatively to gauge changes in systemic flow during the state of shock⁴ and during the inhalation of various gases,⁵ it becomes important to ascertain under what conditions, if any, such assumptions are valid, and whether more reliable information concerning the peripheral circulation may not be obtained from studying other vascular beds.The present study deals with a comparison of the reactions of blood vessels in the hand and forearm to different types of stimuli. An attempt is made (1) to ascertain the relationship of vascular responses in these two areas to changes in the systemic circulation, (2) to evaluate and clarify the mechanisms responsible for the limb-volume changes produced by these stimuli, and (3) to ascertain whether or not the control of blood flow through the forearm differs from that through the hand.     

Responses of vessel walls to chronically applied electrical stimuli

Summary 8 mm long sections of common carotid arteries of conscious, freely moving rabbits were electrically stimulated with DC-impulses by chronically implanted gold-electrodes daily for 1/2h or two time 1/2h per day for 4–6 weeks. The electrodes were arranged in such a way that the wall was stimulated transmurally. In the initial phase the tension of the vessel wall increased. After 1/2 h of stimulation the artery wall relaxed at the stimulated section. Repetition of stimuli led to smooth muscle cell proliferation within the stimulated region. The smooth muscle cells formed a cushion protruding into the lumen of the artery mainly at the anodic site of the stimulation-arrangement. The proliferating cells were smaller than those of the underlying tunica media. They were identified as smooth muscle cells by electron-microscopy, contained relatively more lysosomes and endoplasmic reticulum than the original media-cells and produced collagen-fibrils and elastic fibrils as an extracellular matrix material. Below very thick cushions of smooth muscle cells necrosis developed.Animals which were additionally fed with 2% cholesterol in normal food developed typical atheromatous plaques at the site of the anodic stimuli.

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Lokale Reaktionen der Gefäßwand auf chronische applizierte elektrische Reize

Zusammenfassung Um eine Arteria carotis von Kaninchen wurde eine 8 mm lange Manschette aus Teflon so locker herumgelegt, daß die Pulsationen des Gefäßes nicht behindert waren. In die Manschette waren 1 mm breite, 8 mm lange Goldelektroden eingebaut, die eine transmurale Reizung des Gefäßes ermöglichten. Durch entsprechende Reizanordnung wurden die Arterien der wachen, frei beweglichen Tiere täglich mit stromkonstanten Gleichstromimpulsen eine halbe Stunde oder 2 x eine halbe Stunde lang während einer Versuchsdauer bis zu 6 Wochen gereizt. Die kontralaterale Arterie diente als Kontrollgefäß. Sie wurde ebenfalls mit einer Manschette ungeben, aber nicht elektrisch gereizt. Nach einer halben Stunde Reizzeit (10 Hz, 1,5 mA, 1 ms/Imp) erschlafften die Gefäßwände nach initialer Konstriktion. Wiederholung der Reize bewirkte Proliferation der subendothelialen Gefäßwandzellen in der gereizten Region, vor allem innerhalb des Anodenbereichs. Die proliferierten Zellen wurden elektronenmikroskopisch als glatte Muskelzellen identifiziert. Sie enthielten relativ mehr Lysosomen und endoplasmatisches Retikulum als die ursprünglichen Mediazellen und produzierten kollagene Fasern und elastische Fasern als extrazelluläres Matrix-Material. Unter den sich in das Gefäßlumen hineinentwickelnden dicken Kissen von glatten Muskelzellen entstanden medianahe Nekrosen.Tiere, die zusätzlich 2% Cholesterin in der Nahrung erhielten, entwickelten anodennah typische atheromatöse Plaques.

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With 7 figures

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Supported by a grant of the Cilag-Foundation     

Proliferative responses of human intraepithelial lymphocytes to various T-cell stimuli

Human intraepithelial lymphocytes (IEL) are CD8+ T cells located between intestinal epithelial cells, capable of only minimal proliferation to mitogens but brisk proliferation to mitogens combined with sheep red blood cells. This study examines this differential response of IEL. Both IEL and CD8+ T lymphocytes from the peripheral blood are predominantly CD2+, CD3+, CD4-, CD5+, CD8+, and express the alpha beta subunits of the T-cell receptor. Human IEL express the same densities of the CD2, CD3, and CD8 antigens but a lower density of the CD5 antigen than do peripheral blood CD8+ T cells. The proliferation of IEL is significantly less than that of peripheral blood CD8+ T lymphocytes in response to phytohemagglutinin, to concanavalin A, or to anti-CD3 antibody bound to Sepharose (p less than 0.05). Supplementing IEL with interleukin-1, interleukin-2, or autologous peripheral blood macrophages does not completely reconstitute the proliferative response of IEL to these stimuli. Rather, the low proliferation of IEL to these stimuli is due to incomplete activation, as demonstrated by the low percentage of CD25 (Tac)+ lymphocytes with concanavalin A or the low density of the CD25 antigen with phytohemagglutinin. Both IEL and peripheral blood CD8+ T lymphocytes proliferate minimally in response to alloantigens or to interleukin-2, but briskly in response to stimuli of the CD2 receptor such as the combination of anti-T11(2) and anti-T11(3) antibodies or mitogen and sheep red blood cells. The sheep red blood cells enhance the mitogen-induced response of IEL by augmenting events of activation, both interleukin-2 production and interleukin-2 receptor expression. Thus, IEL represent an unusual compartment of CD2+, CD3+ T lymphocytes that are activated more completely by stimuli of the CD2 receptor than by stimuli of the CD3 receptor or by T-cell mitogens.     

Suckling increases the proportions of mammotropes responsive to various prolactin-releasing stimuli

It is well established that the suckling stimulus sensitizes or primes the anterior pituitary to PRL-releasing stimuli. It is also recognized that PRL-secreting cells from a given animal are not all alike but instead exhibit a considerable degree of functional heterogeneity. The goal of the present study was to determine whether the suckling-induced priming phenomenon is manifest at the cellular level by shifts in the relative abundance of various mammotrope subpopulations. This was accomplished by using reverse hemolytic plaque assays to evaluate the secretory characteristics of individual PRL secretors derived from lactating rats either before or after the transient application of a suckling stimulus. Groups of day 10 lactating rats separated from their litters for 4 h were either killed immediately or were reunited briefly (10 min) with their pups before death. Adenohypophyseal cells obtained after trypsin dispersion were then subjected to plaque assays for PRL. Mammotropes derived from suckled rats were, on average, considerably more responsive to the stimulatory actions of TRH and angiotensin II and less susceptible to inhibition by dopamine. Mammotropes from nonsuckled rats exhibited a bimodal frequency distribution in which plaques from the second mode were roughly 6-8 times larger (released considerably more PRL) than those from the first. Superimposition of suckling (or in vitro treatment with dopamine) caused the second mode to disappear. Suckling also enhanced greatly the fraction of PRL cells that shifted from the first to the second mode (i.e. released more hormone) after treatment with TRH or angiotensin II. Taken together, our results demonstrate that the suckling-induced sensitization of pituitary tissue to PRL-releasing stimuli is manifest at the cellular level as proportional shifts toward those cells most responsive to stimulatory secretagogues and away from those most susceptible to inhibition by dopamine.     

Trigeminal nasal receptors related to respiration and to various stimuli in cats

In twenty adult cats of either sex under nembutal anaesthesia, we aimed at delineating the sensitive territory of trigeminal nerves innervating the nasal mucosa. The different trigeminal nerves (anterior ethmoidal, posterior nasal and infraorbital nerves) were dissected in the orbit. Activity of these nerves was recorded during spontaneous nasal and tracheal breathing and in response to various stimuli: mechanical (manual probing and air jets) and irritants (ammonia vapours). Multiple and unitary activity recorded in nerve filaments enabled a classification of the receptors on the basis of their discharge pattern as rapidly-, intermediately- or slowly adapting receptors, and as drive or non-drive nasal receptors depending on whether or not the respiratory modulation was preserved during tracheal breathing.     

Lung defenses in aging: Responses to influenza vaccine and inflammatory stimuli

This study examined the immunobiologic properties of the respiratory tract in young adult and aged rats. Macrophages obtained by lung lavage technique were enumerated and tested in vitro for migratory, phagocytic and fungicidal activities. Bronchoalveolar lavage (BAL) fluids from the animals were assessed for C5 cleaving activities. Circulatory antibody responses following intranasal immunization with influenza subunit vaccine were determined by ELISA technique. Total numbers of alveolar cells and their differential distribution were comparable between the two groups. Phagocytosis and fungicidal capabilities of the lung-derived macrophages at 60, 120, and 180 minutes of incubation were not different in young adult and aged animals. Random and directed migration of macrophages in vitro remained unaltered. C5 cleaving activities of the BAL fluids were significantly enhanced in the aged animals. In contrast, specific antibody responses to influenza vaccine declined in the aged rats compared to the young adult rats. Aging may adversely affect immunologic balance of the respiratory tract by reducing specific protective immune responses and enhancing ability to mount inflammatory reactions.     

Luminal gastric somatostatin-like immunoreactivity in response to various stimuli in man

This study investigates release of somatostatin-like immunoreactivity (SLI) into the gastric lumen of five healthy human subjects in response to pharmacological stimuli (pentagastrin and secretin) and physiological stimuli (sham feeding and intrajejunal perfusion of elemental diet). Basal and poststimulation gastric juice aspirates were collected at 15-min intervals, extracted with acetone, and SLI determined by radioimmunoassay, with these results: (1) A considerable amount of SLI was secreted during the basal period. (2) Pentagastrin stimulated SLI release quickly and was associated with increased acid secretion. (3) Both secretin and sham feeding increased SLI only slightly. (4) During intrajejunal perfusion of the elemental diet, SLI increased significantly, was associated with decreased acid secretion, and rapidly returned to basal level when elemental diet was replaced by saline. Basal levels of gastric luminal SLI thus showed distinct changes in response to each stimulus. Although the physiological action of luminal SLI remains to be studied, its levels may reflect gastric D-cell activities.This study was supported by the Gastroenterology Section Research Fund 530569.