The potentiation of the histamine release induced by adenosine in mast cells from guinea pig lung and heart: sharp dependence on the time of preincubation

Purinergic signalling and immune cells

This review article provides a historical perspective on the role of purinergic signalling in the regulation of various subsets of immune cells from early discoveries to current understanding. It is now recognised that adenosine 5'-triphosphate (ATP) and other nucleotides are released from cells following stress or injury. They can act on virtually all subsets of immune cells through a spectrum of P2X ligand-gated ion channels and G protein-coupled P2Y receptors. Furthermore, ATP is rapidly degraded into adenosine by ectonucleotidases such as CD39 and CD73, and adenosine exerts additional regulatory effects through its own receptors. The resulting effect ranges from stimulation to tolerance depending on the amount and time courses of nucleotides released, and the balance between ATP and adenosine. This review identifies the various receptors involved in the different subsets of immune cells and their effects on the function of these cells.

Eupatilin blocks mediator release via tyrosine kinase inhibition in activated guinea pig lung mast cells

Eupatilin, an extract from Artemisia asiatica Nakai, is known to exert anti-gastric ulcer, anticancer, and anti-inflammatory effects. The aim of this study was to elucidate whether eupatilin has antiallergic reactions in activated guinea pig lung mast cells compared to apigenin and genistein. Mast cells were purified from guinea pig lung tissues by using enzyme digestion and rough and discontinuous density Percoll gradient. The purified mast cells were sensitized with immunoglobulin (Ig) G(1) (anti-OVA antibody) and challenged with ovalbumin (OVA). Histamine was assayed using an automated fluorometric analyzer, leukotrienes by radioimmunoassay, and tyrosine phosphorylation by immunoblotting. Intracellular Ca(2+) was analyzed by confocal laser scanning microscopy, protein kinase C (PKC) activity using protein phosphorylated with [gamma-(32)P]ATP, and phopholipase D activity (PLD) and phosphatidic acid by using labeled phosphatidyl alcohol. Eupatilin, apigenin, or genistein reduced histamine release and leukotriene synthesis in a does-dependent manner. Eupatilin inhibited mediators to a greater extent than apigenin or genistein. Eupatilin, apigenin, and genistein initially blocked phosphorylation of Syk tyrosine and Ca(2+) influx, PLD activity, phosphatidic acid, and Ca(2+)-dependent PKC alpha/betaII activities during mast cell activation in a dose-dependent manner. Our data suggest that eupatilin initially inhibits Syk kinase, and then blocks downstream multisignal pathways and Ca(2+) influx during mast cell activation triggered by a specific antigen-antibody reaction. Thus, eupatilin may have use clinically as a treatment for inflammatory disorders associated with allergic diseases including asthma.

Ischaemic preconditioning and mast cell histamine release: microdialysis of isolated rat hearts

The aim of this study was to investigate the feasibility of intramyocardium kinetics of histamine release by microdialysis in the isolated rat heart and ascertain if the inhibition of histamine release is implicated in the antiarrhythmic effect of preconditioning. A 30 min normothermic global ischaemia model followed by 30 min reperfusion was carried out in the control group (n= 9). In the preconditioning group (n= 8) there was a 5 min global ischaemia followed by 10 min of reperfusion. A mast cell stabilizing group received the disodium cromoglycate ( 10 micro M, n= 10). The last group received a mast cell degranulator, compound 48/80 (1micro g ml (-1), n= 10). In the control group, the histamine release during reperfusion was significantly different from the basal concentration ( 18.4 +/- 6.5 vs 1.9 +/- 0.5 nM, P< 0.05) and was associated with a maximal period of severe arrhythmias. The ischaemic preconditioning modified the histamine release kinetics with an early mast cell degranulation ( 9.7 +/- 1.5 nM) and a significant decrease in the total period of severe arrhythmias in comparison with the control group ( P< 0.05). In the disodium cromoglycate group, the histamine release during reperfusion decreased ( 3.1 +/- 0.7 nM) and was associated with a maximal period of severe arrhythmias. In the C48/80 group, the increase in the histamine released during reperfusion ( 21.2 +/- 5.0 nM) was associated with a maximal period of severe arrhythmias. These results showed firstly the feasibility of kinetic histamine release in myocardium interstitial fluid on the isolated rat heart and secondly that the inhibition of histamine release did not play a direct role in the antiarrhythmic effect of preconditioning.