Induction of platelet aggregation in vitro by microbubbles of nitrogen.
Microbubbles of nitrogen gas act as a platelet agonist, but the biochemical mechanisms involved in bubble-induced platelet activation are not well known. One characteristic property of a platelet agonist is to potentiate the response by another agonist in a synergistic manner at low concentrations. Possible synergism between N2 gas bubbles and the physiologic agonists ADP, epinephrine, and 5-hydroxytryptamine (5-HT) was tested. The interaction with ADP was additive; N2 microbubbles and ADP had different aggregation profiles, and the bubbles made the reversible ADP aggregation irreversible. Epinephrine caused a strong, synergistic stimulation of bubble-induced platelet aggregation. This synergism was only partially inhibited by indomethacin and acetylsalicylic acid, but abolished by yohimbine. 5-HT had an inhibitory effect on N2 microbubble-induced platelet aggregation. This effect was neutralized by the S2-serotonergic receptor blocker ketanserin. Microbubble stimulation of the platelets before stimulation with ADP, epinephrine, and 5-HT seemed to make them more sensitive to epinephrine only. The strong synergism between microbubbles and epinephrine in vitro should be evaluated for possible future use in predive selection of divers.
Thorsen
T
T
Department of Anesthesiology, University of Bergen, Norway.
Lie
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RT
Holmsen
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H
D000244:Adenosine Diphosphate / Q000494:pharmacology; D001241:Aspirin / Q000494:pharmacology; D004357:Drug Synergism; D004837:Epinephrine / Q000494:pharmacology; D005740:Gases / Q000494:pharmacology*; D006801:Humans; D066298:In Vitro Techniques; D007213:Indomethacin / Q000494:pharmacology; D007650:Ketanserin / Q000494:pharmacology; D009584:Nitrogen / Q000494:pharmacology*; D010974:Platelet Aggregation / Q000187:drug effects*; D012701:Serotonin / Q000494:pharmacology; D015016:Yohimbine / Q000494:pharmacology
D005740:Gases; D015016:Yohimbine; D012701:Serotonin; D000244:Adenosine Diphosphate; D007650:Ketanserin; D009584:Nitrogen; D001241:Aspirin; D007213:Indomethacin; D004837:Epinephrine