Synergistic effects of adrenaline and mepyramine on the anaphylactic reactions of the bronchi and pulmonary vessels in the guinea pig heart-lung-preparation

Non-steroidal anti-inflammatory drugs if combined with anti-histamine and anti-serotonin agents interfere with the bronchial and platelet effects of "platelet-activating factor" (PAF-acether)

The non-steroidal anti-inflammatory drugs (NSAID) indomethacin, aspirin and salicylic acid, as well as the anti-histamine, mepyramine, and the anti-serotonin, methysergide, fail to interfere with bronchoconstriction, thrombo-cytopenia and hypotension induced by platelet-activating factor (PAF-acether, 1-O-octadecyl-2-acetyl-sn-3-glycerylphosphorylcholine) in the guinea-pig. When one of the NSAID was given combined with mepyramine and with methysergide, bronchoconstriction was suppressed, but thrombocytopenia and hypotension persisted. Platelets prepared from blood collected from animals treated with the NSAID or with mepyramine and/or methysergide, aggregated to a similar extent to PAF-acether; however, the accompanying release of ATP was inhibited in those animals which had been treated with the drug combination effective in vivo against bronchoconstriction. In vitro application to platelets of the drugs effective in vivo and ex vivo was ineffective in blocking the platelet-release reaction. This suggests the existence of in vivo sites of action for the synergistic inhibitory activity of NSAID and anti-histamine/anti-serotonin drugs on bronchoconstriction and on platelet secretion. PAF-acether possible releases from the platelets a bronchoconstrictor component, distinguishable from thromboxane A2 and depleted by reserpine administration to the animals, which could account for the in vivo effects on the bronchopulmonary system.

Activation of guinea-pig platelets induced by convulxin, a substance extracted from the venom of Crotalus durissus cascavella

Convulxin (Cx), a component of the venom of the snake Crotalus durissus cascavella, induced the concentration-dependent aggregation of guinea-pig platelets when used at and above 50 +/- 5 ng/ml, accompanied by the release of ATP and by the formation of thromboxanes (Tx). Platelet activation by Cx was not due to potential contaminants found in the crude snake venom, such as phospholipase A2 and clotting enzymes. Aspirin (50-100 microM) failed to interfere with the platelet effects of Cx, demonstrating independence from cyclo-oxygenase. In contrast, indomethacin (50 microM) displayed a distinct inhibitory activity on the effects of Cx, as compared to aspirin, and thus exerts cyclo-oxygenase-independent effects on platelet activation. The ADP scavenger creatine phosphate/creatine phosphokinase (CP/CPK) inhibited aggregation by Cx used at concentrations below 6-8 times the threshold, but failed to interfere with higher amounts. Platelet aggregation by Cx was inhibited and reversed once established by EDTA (5mM) and by prostacyclin (0.1-1 microM). Cx-induced activation of platelets is thus Ca2+-dependent and liable to control by the adenylate cyclase-cyclic AMP system. Convulxin induced hypotension, bronchoconstriction and thrombocytopenia when injected i.v. to the anesthetised guinea pig at 0.3-3 microgram/kg. Aspirin and indomethacin (20 and 5 mg/kg respectively) mepyramine and methysergide (02. mg/kg) failed to interfere with these effects, but the combination of either aspirin or indomethacin with methysergide and mepyramine, suppressed the bronchial effects of Cx, leaving the hypotensive and thrombopenic effects unchanged. This synergism remains unexplained. Bronchoconstriction was platelet-dependent, being suppressed by platelet depletion with antiplatelet serum or by i.v. prostacyclin (1-10 microgram/kg).

[Electrocardiogramme in anaphylactic shock in humans (author's transl)]

Twenty clinical cases described in the literature were gathered, in which electrocardiographic tracings had been recorded. Electrocardiographic changes were found in all cases, such as sinus tachycardia (12 times), impaired electrical conduction (5 times), ventricular overexcitability (7 times), high P-wave (6 times), changes of the ST (10 times), and of the T-wave (18 times). The reason for these changes might be of a complex nature. Based on experimental investiagations mentioned in the discussion, it may be assumed that beside a direct effect on the myocardial cells, the following mechanisms could have influenced the electrical heart potentials: 1. a constriction of the coronary vessels, 2. a pulmonary vascular constriction, 3. an aggregation of thrombocytes, 4. a peripheral vascular dilatation, 5. a bronchiolar constriction.

Release of creatine kinase by antigen, histamine, and catecholamines

In mepyramine treated, ovalbumin sensitized anaesthetized guinea pigs protracted anaphylactic shock was produced by i.p. injection of antigen, and serum creatine kinase (CK) activities were determined 4, 6, or 17 hrs thereafter. Significant increases above nonsensitized controls were obtained. In nonanaesthetized guinea pigs shock course and serum CK increase were considerably accelerated. Histamine increased the serum CK only when given in high amounts (10 mg/kg) s.c., in the presence or absence of mepyramine. I.p. injection of histamine in mepyramine treated animals had no effect. Adrenaline (1 or 10 mg/kg) given as a s.c. depot in oil produced a significant increase of serum CK, as well as noradrenaline (0.1, 1, or 10 mg/kg). Dibenamine reduced the effect of adrenaline. In isolated perfused guinea pig hearts a significant CK liberation occurred already within the first hour after eliciting anaphylaxis. Nonanaphylactic hearts released CK too, but significant amounts were obtained only in the total 4 hrs after ovalbumin administration. Isolated anaphylactic hearts incubated in Tyrode solution liberated significantly more CK than did nonsensitized control hearts. The findings are discussed in view of a possible myocardial damage in anaphylaxis.

Myocardial damage during protracted anaphylactic shock in guinea pigs

In ovalbumin-sensitized, mepyramine-treated guinea pigs protracted anaphylactic shock was elicited by i.v. injection of antigen. Diffuse or focal necrosis of myocardial cells was found in animals which died in protracted shock, as well as perivascular and interstitial edema. The antigen effects could be partially imitated by i.v. infusion of high amounts of adrenaline into nonsensitized guinea pigs. When adrenaline was infused during protracted anaphylactic shock, the catecholamine effects did not add to the histological effects of the antigen. Rather, the morphological alterations in the hearts were reduced, whereas the survival times were not increased, but decreased. - The findings are discussed in view of the nature of protracted anaphylactic shock.