Uptake of histamine by mouse peritoneal macrophages and a macrophage cell line,RAW264.7

We have previously demonstrated that dietary histamine is accumulated in the spleens of L-histidine decarboxylase (HDC)-deficient mice, which lack endogenous histamine synthesis. To characterize the clearance system for dietary histamine in mice, we investigated the cell type and mechanism responsible for histamine uptake in the spleens of HDC-deficient mice. Immunohistochemical analyses using an antihistamine antibody indicated that a portion of the CD14⁺ cells in the spleen is involved in histamine storage. Peritoneal macrophages obtained from Balb/c mice and a mouse macrophage cell line, RAW264.7, had potential for histamine uptake, which was characterized by a low affinity and high capacity for histamine. The histamine uptake by RAW264.7 cells was observed at physiological temperature and was potently inhibited by pyrilamine, chlorpromazine, quinidine, and chloroquine, moderately inhibited by N-methylhistamine, dopamine, and serotonin, and not affected by tetraethylammonium and 1-methyl-4-phenylpyridinium. Intracellular histamine was not metabolized in RAW264.7 cells and was released at physiological temperature in the absence of extracellular histamine. These results suggest that histamine uptake by macrophages may be involved in the clearance of histamine in the local histamine-enriched environment. cation transporter; chlorpromazine; pyrilamine; quinidine     

Uptake and methylation of histamine by dispersed gastric mucosal cells and its possible influence on acid secretion

Inactivation of histamine by gastric mucosal tissue was examined in dispersed rabbit gastric mucosal cells. Mucosal cells were incubated with [14C]histamine. The formed radioactive metabolites were separated and identified by thin layer co-chromatography and quantitated, in both the cellular and extracellular mediums. Gastric mucosal cells internalized histamine, most of which was immediately methylated primarily to N tau-methylhistamine and released. Cellular histamine product accumulation reached a plateau. The rate of histamine methylation increased with increasing extracellular histamine concentration, moving towards a plateau above 5 microM. Histamine methylation was greatly decreased but not abolished at 4 degrees C, in the absence of Na+ and by phlorizin (0.5 mM), an inhibitor of Na(+)-dependent co-transport. Inhibition of histamine N-methyltransferase decreased intracellular methylhistamine content dose dependently without increasing intracellular histamine. The secretagogues pentagastrin and carbachol did not influence histamine metabolism but ethanol inhibited methylation. The data suggest that gastric mucosal cells take up histamine by a Na(+)-dependent and Na(+)-independent process. The histamine uptake capacity appears to be linked to the methylation activity within the cell. The decrease in histamine uptake and metabolism caused by ethanol could potentially increase histamine concentrations near the target cells and be the reason for the stimulatory effect of ethanol on acid secretion.     

Uptake of the neurotransmitter histamine into the eyes of larvae of the barnacle (Balanus amphitrite)

The photoreceptors of adult barnacles use histamine as their neurotransmitter and take up (3)H-histamine selectively from the extracellular medium. We assayed for the uptake of (3)H-histamine into the eyes of the free-swimming (nauplius) and settling (cyprid) larval stages of Balanus amphitrite. The extracellular space of nauplii proved permeable to dyes below about 800 molecular weight (MW), indicating that (3)H-histamine (MW 111) introduced into seawater would have access to internal structures. (3)H-Histamine was taken up into nauplii by a process with a K(D) of 0.32 microM. Uptake was antagonized by chlorpromazine, which also blocks uptake of (3)H-histamine into adult photoreceptors. In autoradiographs of serial sections of nauplii and cyprids incubated in (3)H-histamine, the ocelli and compound eyes were labeled; other structures in the animal were not. No eyes or other structures were labeled with (3)H-serotonin, a related amine whose transporter commonly transports histamine as well. These experiments show that a histamine-specific transporter similar to that found in the adult is expressed in all of the eyes of barnacle larvae. In the ocelli, where photoreceptors and pigment cells may be distinguished in the light microscope, label was unexpectedly concentrated far more over the pigment cells than over the photoreceptors.     

The subcellular localization of histamine and histamine methyltransferase in rat brain

Abstract— We have examined the subcellular localization of histamine and histamine methyl-transferase (S-adenosylmethionine: histamine 7V-methyltransferase; EC 2.1.1.8) in rat brain. The highest levels of histamine and histamine methyltransferase activity were found in the hypothalamus. A large proportion of hypothalamic histamine and histamine methyltransferase activity was found in particles with sedimentation properties in sucrose gradients similar to synaptosomes storing norepinephrine and serotonin. Histamine displayed a bimodal distribution in sucrose gradients. A substantial amount of a tracer dose of [³H]histamine added to hypothalamic homogenates at 4°C was bound to particulate fractions, suggesting that endogenous histamine may redistribute and bind to subcellular fractions during homogenization. The second, lighter peak of histamine in sucrose gradients was thought to be due to histamine that redistributed during homogenization.     

Effect of histamine and histamine antagonists on the glycogen content of Tetrahymena

The glycogen content of Tetrahymena pyriformis was analysed by a cytophotometric method. Histamine and histamine antagonists were found to influence the glycogen content. It increases after acute histamine treatment, while it decreases after 4 days incubation with histamine. The H2 receptor antagonist methiamide was more effective than histamine, while the H1 receptor antagonist phenindamine had no effect on the glycogen content. The effect reflects the similarity or dissimilarity of the chemical structure of the antagonists and of histamine. Subdivision of the cytophotometric results indicated that all of the protozoa react to histamine or to its antagonists, but all agents increased the number of glycogen-rich Tetrahymena.     

Refractoriness for ultrasonically nebulized distilled water and histamine after histamine challenge

Refractoriness for bronchial provocation frequently occurs after different challenge tests used to assess bronchial hyperresponsiveness in asthmatic patients. We investigated whether histamine inhalation could cause refractoriness for bronchoconstriction induced by ultrasonically nebulized distilled water (UNDW) and whether histamine causes tachyphylaxis for a subsequent histamine challenge in nine stable asthmatic patients. Preinhalation of histamine induced a significant diminished bronchoconstrictor response to UNDW cumulative dose of inhaled UNDW causing a 20% fall in forced expired volume in 1 s. The mean increased from 3.5 +/- 0.8 to 11.8 +/- 2.6 (SE) ml after histamine challenge (P less than 0.01). However, repeated inhalation of histamine did not change the bronchoconstrictor response to histamine within 1 h after rechallenge (P greater than 0.5). The magnitude of refractoriness for UNDW inhalation after preinhalation of histamine was correlated to the bronchoconstrictor response to histamine (r = 0.73, P less than 0.05). We conclude that inhaled histamine can induce refractoriness for UNDW, which seems to be related to the degree of bronchial hyperresponsiveness.     

Binding of histamine and histamine analogs to lymphocyte subsets analyzed by flow cytometry

The binding of histamine, 4-methylhistamine (a histamine type 2 receptor agonist), cimetidine (a histamine type 2 receptor antagonist), and telemethylhistamine (an inactive analog) to human peripheral blood mononuclear cell subsets was investigated by flow cytometry by using conjugates of these ligands coupled to fluorescein-labeled human serum albumin. Our results indicate that binding of fluorescent protein conjugates of histamine and its analogs does not selectively identify a lymphocyte subset(s) that mediates the immunomodulatory effects of histaminergic ligands. Conjugates with both low (2.5 to 2.8:1) and high (28 to 57:1) ligand to protein coupling ratios were used. No binding above background could be detected for the low mole ratio reagents. The high mole ratio reagents were bound by 95 to 99% of all lymphocytes when used at ligand concentrations of 50 microM or greater. At lower ligand concentrations, the number of lymphocytes exceeding a set fluorescence threshold was decreased, but fluorescence distributions remained unimodal at all concentrations used (1 to 500 microM). Monocytes also bound the high mole ratio reagents and gave rise to a second high-intensity peak in the fluorescence distribution unless they were excluded by other means. Levels of conjugate binding detected by flow cytometry did not parallel ligand potencies at classical histamine type 2 receptors; at equivalent ligand concentrations, approximately equal amounts of histamine or 4-methylhistamine conjugate were bound per lymphocyte, and only 30% less telemethylhistamine conjugate was bound. Competition with free ligands (10(2)- to 10(4)-fold excess histamine, 4-methylhistamine, cimetidine, or telemethylhistamine) did not significantly decrease the level of binding observed for the high mole ratio reagents at bound ligand concentrations of 1 to 25 microM. Dual staining with fluorescein-labeled conjugate and phycoerythrin-labeled monoclonal antibodies Leu-3ab (anti-helper T), Leu-2a (anti-suppressor T), Leu-M3 (anti-monocyte), or anti-HLA-DR (B cells and monocytes) was also carried out. The extent of conjugate binding to helper and suppressor cells was identical for each of the ligands used, but higher levels of conjugate binding were seen for monocytes and B cells than for T cells in every case. Our data do not exclude the possibility of enhanced conjugate binding to small numbers of activated (HLA-DR positive) T cells that might be involved in mediation of histamine effects.(ABSTRACT TRUNCATED AT 400 WORDS)     

Characterization of Cadmium Uptake in Lactobacillus plantarum and Isolation of Cadmium and Manganese Uptake Mutants

Two different Cd²⁺ uptake systems were identified in Lactobacillus plantarum. One is a high-affinity, high-velocity Mn²⁺ uptake system which also takes up Cd²⁺ and is induced by Mn²⁺ starvation. The calculated K_m and V_max are 0.26 μM and 3.6 μmol g of dry cell⁻¹ min⁻¹, respectively. Unlike Mn²⁺ uptake, which is facilitated by citrate and related tricarboxylic acids, Cd²⁺ uptake is weakly inhibited by citrate. Cd²⁺ and Mn²⁺ are competitive inhibitors of each other, and the affinity of the system for Cd²⁺ is higher than that for Mn²⁺. The other Cd²⁺ uptake system is expressed in Mn²⁺-sufficient cells, and no K_m can be calculated for it because uptake is nonsaturable. Mn²⁺ does not compete for transport through this system, nor does any other tested cation, i.e., Zn²⁺, Cu²⁺, Co²⁺, Mg²⁺, Ca²⁺, Fe²⁺, or Ni²⁺. Both systems require energy, since uncouplers completely inhibit their activities. Two Mn²⁺-dependent L. plantarum mutants were isolated by chemical mutagenesis and ampicillin enrichment. They required more than 5,000 times as much Mn²⁺ for growth as the parental strain. Mn²⁺ starvation-induced Cd²⁺ uptake in both mutants was less than 5% the wild-type rate. The low level of long-term Mn²⁺ or Cd²⁺ accumulation by the mutant strains also shows that the mutations eliminate the high-affinity Mn²⁺ and Cd²⁺ uptake system.