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This study describes the effects of the beta 2 receptor agonist terbutaline on platelet sequestration in sheep exposed to endotoxin shock. The in vivo behavior of Indium-111-labeled platelets was followed simultaneously in the lungs, liver, spleen, and kidneys. The effects on the respiratory function and the central hemodynamics were also followed. Twelve adult sheep were given endotoxin (10 micrograms/kg bw), and six of those received a continuous intravenous infusion of terbutaline (20 micrograms/kg/hr) during 4 hr, starting 30 min after injection of endotoxin. The other six acted as controls. It was found that a marked pulmonary and hepatic platelet sequestration occurred during and just after the endotoxin infusion and was followed by a marked platelet disaggregation within 30 min in both groups. Three hours after the endotoxin a second wave of platelet trapping occurred in the control animals in both the lungs and the liver, while no such increase was seen in the terbutaline-treated animals. In the spleen, however, there was a decrease in platelet sequestration after endotoxin in both groups, and in the kidneys only minor changes occurred. Furthermore, less marked hemodynamic and respiratory alterations occurred in the terbutaline group compared with the controls. It was concluded that terbutaline decreased sequestration of platelets in the lungs and in the liver of sheep in endotoxin shock, which may be of importance in the development of multiple organ failure.

80% of patients with chronic autoimmune thrombocytopenic purpura (ATP) may reach normalization of platelet count after steroids or splenectomy. In some of these cases a bleeding tendency may still persist and this has been attributed to abnormalities of platelet function resulting from the effect of platelet-bound antibodies. We have studied 49 ATP patients in order to assess the frequency and the pattern of this immune thrombopathia, and the correlation with the levels of platelet associated IgG (PAIgG). Only 3 patients (6%) had prolonged bleeding time and persistence of mucocutaneous haemorrhages, whereas 36% presented an altered platelet aggregation pattern. Platelet serotonin content, platelet and plasma beta-thromboglobulin concentration, and malondialdehyde generation after thrombin stimulus were found also altered, but the findings were not clearly correlated with the concentration of PAIgG.