Liberation of histamine by compound 48/80, tolazoline,betahistine and burimamide from isolated spontaneously beating guinea pig and rabbit atrial pairs

Tolazoline, betahistine, burimamide and compound 48/80 release histamine from isolated guinea pig atria resulting in histamine concentrations that will stimulate H₂-receptors. Tolazoline, burimamide and 48/80 also release histamine from rabbit atria but do not result in histamine concentrations that will stimulate either H₁- or H₂-receptors. However, betahistine (which does not release histamine from rabbit atria) and tolazoline stimulate the rabbit atrial chronotropic response by releasing catecholamines.     

The effect of compound 48/80 on the carbachol-evoked acid secretion of the isolated mouse stomach

The aim of the present work was to determine in the isolated mouse stomach whether the depletion of mast cell histamine by compound 48/80 influences the acid secretion, evoked by carbachol. Each effect of carbachol was compared to the effect of histamine (10^–6 M), applied after each carbachol application. After carbachol and histamine, compound 48/80 was applied twice or three times successively; the second and the third application were not able to evoke any secretion. After 48/80, the applications of carbachol and histamine were repeated and their effects compared to those before the applications of compound 48/80. Three concentrations of the compound were used: 20, 100 and 500 g/ml. The lowest concentration of the histamine liberator did not significantly change the response to carbachol, The highest one reduced it but the effect of histamine was reduced, too. Compound 48/80 in concentration 100 g/ml significantly augmented the secretory effect of carbachol. The possible explanation for this effect is that histamine, liberated from mast cells, is taken up by some other cells in the tissue from where it is liberated by carbachol stimulation.     

Interaction of substance P, compound 48/80 and mastoparan with the alpha-subunit C-terminus of G protein.

Pretreatment of purified calf brain G proteins with activated pertussis toxin or antibodies raised against the C-terminus of their alpha subunits prevented the increase in GTPase activity induced by substance P, compound 48/80 and mastoparan. These results suggest that these mast cell secretagogues activate G proteins directly via an interaction with the C-terminus of alpha subunits of G proteins by mimicking the agonist-liganded receptors.     

The effect of compound 48/80 and of electrical field stimulation on mast cells in the isolated mouse stomach

It has been shown that compound 48/80 evokes acid secretion in the isolated mouse stomach by releasing histamine from mast cells. The aim of the present work was to study the distribution and type of mast cells in the isolated mouse stomach and to examine the effect of compound 48/80 and of electrical field stimulation (EFS) on these cells.Histological examination of the stomachs showed only the presence of connective tissue mast cells (CTMC) in all parts of the stomach except in the glandular mucosa where mucosal mast cells (MMC) predominated (MMC–71%, CTMC–29%). Compound 48/80 and EFS did not affect MMC, whereas CTMC showed marked degranulation in all parts of the stomach including the glandular mucosa. It can be concluded that CTMC, present in the gastric mucosa and being sensitive also to EFS, may be involved in the regulation of gastric secretion in the mouse.     

The effect of compound 48/80 on the precipitated withdrawal syndrome of dogs

The aim of this study was to eliminate endogenous stores of histamine before inducing the precipitated withdrawal syndrome. Results demonstrate that histamine plays a role in the emergence of some of the symptoms which characterize the precipitated abstinence syndrome in morphine-dependent dogs. Morphine-dependent dogs receiving 0.5 mg/kgn-allyl-normorphine exhibit the precipitated abstinence syndrome. Injection of compound 48/80, 0.5 mg/kg, a potent histamine liberator, produced, on the other hand, typical signs of the abstinence syndrome. A second injection of this compound 24 hours later, however, failed to induced these signs. An injection ofn-allyl-normorphine also failed to induce these signs in dogs pretreated with compound 48/80 despite the fact that the dogs were still on their morphine regime. Control experiments on naive animals showed that injection of 0.5 mg/kgn-allyl-normorphine failed to produce signs of the abstinence syndrome. Injection of compound 48/80, a potent histamine liberator, on the other hand, did produce the typical signs of the abstinence syndrome. Animals pretreated withn-allyl-normorphine followed by compound 48/80 responded similarly to animals treated with compound 48/80 alone.     

Calcium fluxes and contractility in isolated guinea pig atrium: effect of A23187.

The Ca2+ ionophore A23187 (10(-6) to 3 X 10(-5) M) increased the force of contraction is isolated guinea pig atria. In individual twitches, peak tension, maximum rate of tension development, time to peak tension, and total twitch duration were all increased by A23187. Tripelennamine, indomethacin, and atropine did not significantly alter the inotropic effect of A23187. Serotonin produced changes in individual twitches that differed qualitatively and quantitatively from those of A23187. Therefore, the inotropic action of A23187 is probably not mediated by release of endogenous histamine, prostaglandins, acetylcholine, or serotonin. 45Ca influx and efflux were increased by A23187. The enhanced 45Ca efflux exceeded that which would be predicted if the ionophore acted only to increase the passive Ca2+ permeability of the myocardial cell membrane. These results suggest that A23187 facilitates the entry of extracellular Ca2+ into the myocardial cell and the release of intracellular Ca2+ stores into the myoplasm. The resultant increase in intracellular Ca2+ activity could account for the positive inotropic action of A23187.     

Lack of effect of compound 48/80 on human umbilical vein endothelium

Summary Human umbilical veins have been treated with compound 48/80, a histamine liberator factor, in order to obtain information about the histamine content in the Weibel-Palade bodies. Ultrastructural observations show a lack of effect in the morphology of this organelle. Our findings suggest that the Weibel-Palade bodies are not histamine storage organelles in human umbilical vein.     

Comparison of substance P-induced and compound 48/80-induced neutrophil infiltrations in mouse skin.

It has recently been shown that substance P induces neutrophil infiltration in the skin, which is mediated through mast cell degranulation. Since substance P activates both skin mast cells and vascular endothelial cells, we compared the potencies of substance P and a mast cell-degranulating agent, compound 48/80, which is inactive for vascular endothelial cells, in inducing neutrophil infiltration in mouse skin. We also examined the effect of the C-terminal peptide of substance P, SP6-11, which is active for vascular endothelial cells, on compound 48/80-induced neutrophil infiltration in the skin. Subcutaneous administrations of substance P (10(-7) to 10(-5) M; 0.1 ml) and compound 48/80 (0.5-50 micrograms/ml) induced neutrophil infiltrations and mast cell degranulations in mouse skin in a concentration-dependent fashion. Moreover, substance P induced more neutrophil infiltrations than compound 48/80 in terms of the magnitude of mast cell degranulations. SP6-11 (10(-6) to 10(-4) M) induced no significant neutrophil infiltration or mast cell degranulation, but increased the vascular permeability of endothelial cells in the skin. Furthermore, SP6-11 enhanced compound 48/80-induced neutrophil infiltration without any increase in mast cell degranulation. Our results indicate that, in addition to mast cell degranulation, the activation of vascular endothelial cells is involved in substance P-induced neutrophil infiltration in the skin.     

Indirect adrenergic effect of compound 48/80 in cat cerebral arteries

Compound 48/80 evoked an increase in the spontaneous tritium release from cat cerebral arteries prelabelled with³H-NA. This increase was abolished after cervical gangliectomy, external calcium removal or in the presence of colchicine. Cocaine brought about an enhancement in the release of radioactivity elicited by compound 48/80 while diphenhydramine did not affect it. These results suggest that compound 48/80 has an indirect adrenergic effect in cat cerebral arteries which is not mediated by the release of histamine from mast cells.     

Characterization of the substance P receptor in guinea pig lung tissues

The biologic activity of substance P has been demonstrated to be limited both in in vivo and in vitro by a membrane-bound protease, neutral endopeptidase (EC 3.4.24.11). The interaction of substance P with its receptor on guinea pig lung tissues was studied in the presence of an inhibitor of neutral endopeptidase under conditions that protect the peptide from degradation. Uptake of 0.1 nM [125I]-BH-substance P in lung membrane preparations was rapid at 4 degrees C, reaching equilibrium in 30 to 40 min, and binding was stable for at least 30 min thereafter. Binding was reversible and saturable. Scatchard analyses of saturation binding data are consistent with a single class of receptor molecules in both lung parenchymal and airway membranes, with a Kd of 2 to 3 nM and a receptor density of 4,000 to 5,000 fmol/g wet wt of tissue. In competitive binding experiments, neurokinin A and substance P methyl ester were equipotent and required approximately 100-fold higher concentrations to effect equivalent displacement than unlabeled substance P. Eledoisin also competed for [125I]-BH-substance P binding, but was less effective than the other analogs. The spasmogenically inactive derivative, substance P 1-9, did not compete for substance P binding at concentrations as high as 1 microM. Binding of [125I]-BH-substance P was rapidly and completely reversed by addition of 0.1 mM GTP, suggesting that association with a GTP binding protein is required for high affinity binding of substance P to its receptor in lung. The substance P receptor molecule was further characterized by covalently crosslinking [125I]-BH-substance P to membrane preparations followed by SDS-PAGE of the solubilized material.(ABSTRACT TRUNCATED AT 250 WORDS)     

Mast cells,compound 48/80, and prolonged hypothermia in the rat

In the nonhibernating animal the stress of prolonged deep hypothermia is associated with the development of circulatory symptoms like those of burn-shock. Mast cells are sensitive to a variety of stressors, including thermal ones, and commonly react by releasing vasoactive substances that may facilitate vascular changes similar to those of burnshock. The possible role of mast cells in the complications of prolonged hypothermia was the object of this investigation. Two groups of female albino rats were subjected to 15° C total body hypothermia for 7.5 hr and then rewarmed artificially. Group I had been treated previously with compound 48/80 which depletes the mast cell content of tissues. Group II constituted controls and possessed a normal complement of mast cells. Progressive hemoconcentration was noted in both groups. However, the hematocrits of the 48/80-treated animals were significantly lower at selected intervals than those of control animals. In addition, 100% survival of the 48/80-treated animals was recorded in contrast to a 60% survival rate for controls. Microscopic examination of the mast cells in several tissues of additional controls suggested a loss of granule density during hypothermia and early rewarming. This investigation offers circumstantial evidence that mast cells of the rat facilitate the development of some of the deleterious effects of prolonged hypothermia.     

Observations on the staircase phenomenon in guinea pig atrium

The staircase phenomenon, occurring after a change in frequency was studied in isolated trabeculae from guinea pig atrium. The effects on tension, action potential form and function as well as ionic currents were investigated.

1. In the ascending part of the frequency-force relationship a sudden change to a new driving frequency resulted in a staircase response which consisted of two exponential phases (τ₁ = 1—2 s; τ₂ = 20 — 30 s).
2. The build-up or decline of twitch tension in response to either an increase or reduction of [Ca²⁺]_o followed a similar composed time course.
3. After a reduction in stimulation frequency the action potentials changed time dependently: In the first response the peak of the overshoot was reached faster and the plateau phase was shortened; afterwards these parameters remained constant while the repolarization phase continually shortened during the following 5–10 action potentials.
4. In voltage clamp experiments an analogous reduction in the frequency of depolarizing voltage clamp pulses induced an immediate increase of the slow inward current (I_si). In the following 10 pulses the increased I_si remained constant, while the late outward current continually increased.
5. The time course of recovery of the I_si-system was found to be slow in atrial trabeculae (τ=300–500ms at ?70mV). Thus the increase in I_si, observed after a reduction in frequency, could be explained by a more complete recovery of the I_si-system during the interval between two stimuli.
6. The increase in I_si during these recovery experiments was accompanied by an accelerated inactivation.
7. It is concluded that after a reduction in stimulation rate the faster development of the overshoot and the shortening of the plateau phase are due to an augmentation and a faster inactivation of the I_si, respectively. The shortening of the late repolarization phase which developed during successive action potentials is most probably related to the observed increase in late outward current.

     

苍耳子提取物抑制大鼠肥大细胞活化的机制研究

目的苍耳子具有抗过敏作用,但其作用机制尚未明确。本研究目的是利用能使肥大细胞活化的物质Compound 48/80,探讨苍耳子抗过敏作用机制。方法通过Compound 48/80诱导大鼠被动皮肤过敏反应(PCA)实验,用比色法测定苍耳子提取物在体内对肥大细胞影响。体外实验观察苍耳子提取物对Compound 48/80诱导组胺释放、细胞内钙摄入及细胞内cAMP水平的影响。结果Compound 48/80处理组对比正常组显著增强伊文思蓝的生成、组胺的释放、细胞内钙摄入以及减少cAMP量。苍耳子提取物前处理则明显抑制了Compound 48/80诱导的大鼠PCA实验,组胺的释放、细胞内钙摄入以及cAMP水平减少。结论苍耳子抗过敏作用可能与抑2+制肥大细胞内Ca摄入及增加cAMP量有关。     

Nociceptin-induced histamine release in the brain: comparison with compound 48/80- and substance P-induced amine secretions

Inflammation Research - .     

Sulfuric acid induces airway hyperresponsiveness to substance P in the guinea pig

We investigated whether sulfuric acid inhalation would cause hyperresponsiveness to substance P. Guinea pigs became dyspneic during a 1 h sulfuric acid exposure, but recovered by 24 h when they were challenged with substance P or histamine aerosols. Eight minutes after the start of challenge, animals were killed and excised lung gas volumes measured. Sulfuric acid slightly increased histamine responsiveness compared to controls. However, sulfuric acid caused a much more pronounced leftward shift in the dose response to substance P. Coadministration of the neutral endopeptidase (NEP) inhibitor, thiorphan, did not reduce sulfuric acid-related hyperresponsiveness to substance P. By 72 h, sensitization to substance P was absent. Histological evaluation of sulfuric acid-treated lungs revealed mild alveolitis at 24 h, but not at 72 h. We conclude that sulfuric acid produces a marked sensitization to substance P. Inactivation of NEP does not appear to account for this effect.     

Sulfuric acid induces airway hyperresponsiveness to substance P in the guinea pig

We investigated whether sulfuric acid inhalation would cause hyperresponsiveness to substance P. Guinea pigs became dyspneic during a 1 h sulfuric acid exposure, but recovered by 24 h when they were challenged with substance P or histamine aerosols. Eight minutes after the start of challenge, animals were killed and excised lung gas volumes measured. Sulfuric acid slightly increased histamine responsiveness compared to controls. However, sulfuric acid caused a much more pronounced leftward shift in the dose response to substance P. Coadministration of the neutral endopeptidase (NEP) inhibitor, thiorphan, did not reduce sulfuric acid-related hyperresponsiveness to substance P. By 72 h, sensitization to substance P was absent. Histological evaluation of sulfuric acid-treated lungs revealed mild alveolitis at 24 h, but not at 72 h. We conclude that sulfuric acid produces a marked sensitization to substance P. Inactivation of NEP does not appear to account for this effect.