The response of newly formed blood vessels in healing wounds to histamine and other permeability factors

Changing sensitivity to H1 and H2 receptor antagonists in the growing vasculature

1. Resting albumin efflux is greater from immature vessels than from mature and this is associated with a greater blood flow in immature vessels. 2. Both resting blood flow and albumin efflux in immature vessels are reduced by an H2 antagonist. 3. Histamine produces a greater albumin efflux from mature vessels than from immature and the associated increase in blood flow in response to histamine was also greater in mature vessels. 4. Blood flow and permeability increase produced by histamine are separately mediated via H2 and H1 receptors respectively in mature vessels. 5. In immature vessels, H2 receptors appear to mediate both responses.

The inflammatory reaction in an experimental model of open wounds in the rat. The effect of arachidonic acid metabolites

The study concerned the effect of arachidonic acid metabolites on the inflammatory reaction in granulation tissue of open wounds in rats. Metabolites or inhibitors were applied in a wound chamber attached to circular, open, full-thickness skin wounds 5 days post-wounding. The adjacent wound served as control. Blood flow, albumin extravasation and accumulation of polymorphonuclear leucocytes (PMNLs) were measured in the granulation tissue. Prostaglandin E2 (PGE2 5.7 microM) increased blood flow and albumin extravasation by 95 and 16%, respectively, without affecting PMNLs. Leukotriene B4 (LTB4 2.7 microM) increased PMNL accumulation by 142% without altering albumin extravasation. Indomethacin (28 microM, repeatedly) did not affect blood flow or albumin extravasation, but increased PMNL accumulation by 21%. Methylprednisolone (3.3 mM, repeatedly) reduced blood flow and albumin extravasation by 29 and 31%, respectively, without influencing PMNLs. The granulation tissue obviously responds to exogenous PGE2 and LTB4. Endogenous arachidonic acid metabolites seem to play only a minor role in the inflammatory process in this model.

The role of histamine and serotonin in the inflammatory reaction in an experimental model of open wounds in the rat

The role of histamine and serotonin in the inflammatory reaction in the granulation tissue of open wounds in the rat was studied. The model involved plastic chambers attached to the edges of two open circular full-thickness skin wounds. Five days post-wounding, agonists or antagonists were applied in one of the two chambers, the adjacent wound serving as control. Thereafter blood flow and albumin extravasation were measured. Application of histamine (100 microM) caused an increase in granulation tissue blood flow by 36%, but left albumin extravasation unaffected. Treatment with mepyramine (H1 antagonist, 20 microM), cimetidine (H2 antagonist, 20 microM) or methysergide (serotonin antagonist, 20 microM) did not influence the level of either blood flow or albumin extravasation. It is suggested that endogeneous histamine and serotonin play a minor role in the inflammatory process in the granulation tissue of this model of healing wounds.

Edema-producing activity of group A streptococcal polysaccharide and its possible role in the pathogenesis of cell wall-induced polyarthritis

Edematous responses were induced in the limbs of Sprague-Dawley rats by intravenous, intraperitoneal, or intra-articular injections of group-specific polysaccharide (PS) isolated from the cell walls of group A streptococci. After intravenous injection of the edema-producing PS, vascular permeability increase (measured by 125I-human serum albumin) was detected in the limbs, but not in the heart, lungs, spleen, liver, thymus, kidney, skin, skeletal muscle, submandibular lymph nodes, mesenteric lymph nodes, or ascending colon. This indicates a selective effect on vascular endothelium of the joints. Evidence to suggest that the edema-producing activity of the PS might play an important role in the pathogenesis of cell wall-induced polyarthritis included the following: (a) the presence of edema-producing activity in arthropathogenic cell wall preparations; (b) cell wall preparations without edema-producing activity were significantly less active in inducing arthritis than were those which contained edema-producing activity; and (c) the addition of edema-producing PS to cell wall preparations increased both the incidence and the severity of arthritis.

Variations in the numbers and dimensions of tissue channels after injury

The dimensions and numbers of tissue channels were estimated, using transmission electron microscopy after filling them with ferri-ferrocyanide precipitate, in the subcutaneous tissue of mice. They were studied in the normal condition, and at varying times after a simple incised wound. After this injury they increased very greatly indeed in numbers and dimensions, being maximal at 1 week. Six months elapsed before they returned to normal. The hydraulic conductivity was calculated. It increased by 10(5) times at the maximum, when clinical oedema was present.

Development of enhanced blood flow responses to prostaglandin E1 in carrageenan-induced granulation tissue

The distribution of cardiac output (c.o.) was measured by the radioactive microsphere method in rats at different time intervals after the implantation of carrageenan-impregnated sponges. The amount of blood distributed to the developing granulomata increased from day 5 after sponge implantation to day 7, but showed no further increase at day 10. A similar pattern in blood flow was observed in the skin covering the granulomata. Injection of PGE1 (100 Ng) into the sponges led to an increase in blood flow, the magnitude of which became gradually larger between days 5 and 10. A similar, though less marked increase in sensitivity to PGE1 was observed in the skin covering the granulomata, PGE1 causing a significant increase in blood flow to the skin on day 10. These changes in sensitivity to exogenous PGE1 may be due to decreasing levels of endogenous PGE and/or maturation of the newly formed blood vessels in the granulation tissue.

An ontogenic study of the acute inflammatory response in the fetal rhesus monkey. II. The mediation of increased vascular permeability by histamine, compound 48/80 and bradykinin

Vascular permeability as a function of age was evaluated quantitatively and morphologically in skin of fetal Rhesus monkeys given vasoactive mediators. The response was examined at 90, 120 or 150 days of gestation or at birth and compared to the response of yearling Rhesus monkeys. Skin sites were challenged with histamine, compound 48/80 or bradykinin. Evans' blue and horseradish peroxidase were used as markers of vascular integrity. Evans' blue was quantitated spectrophotometrically. Vascular permeability during fetal life was depressed. Fetal venules and capillaries had poorly formed basement membranes, an abundance of microfilaments within endothelial cells, occasional electron dense endothelial cells and infrequent deposits of extravascular peroxidase.