It is well known that histamine produces constriction via H1 receptors and decreases tracheal smooth muscle tone via H2 and H3 receptors. In addition, it has already been reported that 3-methylhistamine and phenylethylamine are competitive antagonists of histamine N-methyl-transferase (HMT), the enzyme responsible for rapid inactivation of histamine. Our results suggest the possibility that 3me...

Histamine is present in high concentrations in the intestine and we investigated the possibility that it might have a role here in intestinal transport. When added to the basal side of rabbit ileal mucosa in vitro histamine (10(-4)M) induced a short-lived increase in electrical potential difference and short circuit current. It inhibited net chloride absorption but did not influence sodium tran...

WOODS, JAMES R., JR., C. R. BRINKMAN, III, A. DANDAVINO, K. MURAYAMA, AND N. S. ASSALI. Action of histamine and H, and H, blockers on the cardiopulmonary circulation. Am. J. Physiol. 232(l): H73-H78, 1977 or Am. J. Physiol.: Heart Circ. Physiol. l(1): H73-H78, 1977. -Systemic and pulmonary hemodynamic responses to histamine were investigated in chronically instrumented unanesthetized nonpregnan...

Receptors for small endogenous hormones on human leukocytes were studied by insolubilizing the hormones and incubating them with the cells. Histamine, norepinephrine, and prostaglandin E(2) (PGE(2)) were conjugated to either of two types of carrier: (bovine or rabbit) serum albumin or a random copolymer of DL-alanine and L-tyrosine. The conjugates were linked to agarose beads (Sepharose) and th...

Hemodynamic responses to histamine were investigated in the anesthetized rabbit. Intravenous injections of histamine induced dose-dependent decreases in systemic arterial pressure that were blocked by the H1-receptor antagonist pyrilamine but not the H2 antagonist cimetidine. Injections of histamine and the H1 agonist 6-[2-(4-imidazolyl)ethylamine]- N-(4-trifuormethylphenyl)-heptanecardoxamide ...

The diverse physiological functions of histamine are mediated through distinct histamine receptors. Mast cells are major producers of histamine, yet effects of histamine on mast cells are currently unclear. The present study shows that histamine induces chemotaxis of mouse mast cells, without affecting mast cell degranulation. Mast cell chemotaxis toward histamine could be blocked by the dual H...

Histamine, a biological amine, is considered as a principle mediator of many pathological processes regulating several essential events in allergies and autoimmune diseases. It stimulates different biological activities through differential expression of four types of histamine receptors (H1R, H2R, H3R and H4R) on secretion by effector cells (mast cells and basophils) through various immunologi...

objective: crocin, as an active constituent of saffron, has many biological functions including antioxidant and anti-inflammatory activities. the present study was aimed to investigate the effects of crocin and chlorpheniramine on local edema induced by histamine. materials and methods: local edema was induced by subcutaneous injection of histamine (100 μl, 0.1%) in ventral surface of right hin...

C57BL/6 mice immunized i.p. with alloantigen (P815 mastocytoma cells) develop cytolytically active thymus-derived (T) splenic lymphocytes. The definition of specific histamine receptor sites on effector T cells has been studied by measuring the in vitro effects of the hormone on cytolytic activity. Histamine was found to inhibit cytolysis reversibly and to increase lymphoid cell cyclic AMP leve...

Data concerning cardiovascular effects of peripherally and centrally located histamine H(3) receptor stimulation are contradictory, and despite excessive studies their role in the control of the cardiovascular function have not been cleared yet. Effect of histamine H(3) receptors activation have been attributed to modulation of sympathetic system activity but exact role of peripherally and cent...