Isoprenaline inhibits thromboxane B2 release from U937 cells.
The U937 monocytic cell line and its differentiated macrophage-like form have been well characterized, illustrating many similarities with their analogous in vivo cells. We examined the release of thromboxane B2 (TXB2) from undifferentiated and differentiated cells after stimulation with opsonized zymosan and investigated whether the release of this mediator could be modified by isoprenaline. After stimulation, the U937 cells released TXB2 in a dose-dependent manner, with the release greater from the differentiated cells. The TXB2 released was inhibited by flurbiprofen (> 10(-8) M; P < .01) and isoprenaline (> 10(-6) M; P < .01), and the inhibition was reversed by propranolol (10(-6) M; P < .02). Thus, it is clear that undifferentiated and differentiated U937 cells release TXB2, which can be inhibited by beta 2-adrenoceptor stimulation. These findings illustrate an important functional difference between the in vivo macrophages and differentiated U937 cells because beta 2-adrenoceptor stimulation does not inhibit mediator release from macrophages.
Department of Clinical Pharmacology, Royal Postgraduate Medical School, Hammersmith Hospital, London, United Kingdom.
C E
CE
Brightling
A J
AJ
Baker
R W
RW
Fuller
D002471:Cell Transformation, Neoplastic / Q000473:pathology; D004305:Dose-Response Relationship, Drug; D005480:Flurbiprofen / Q000494:pharmacology; D006801:Humans; D007545:Isoproterenol / Q000494:pharmacology*; D007948:Leukemia, Monocytic, Acute / Q000378:metabolism* / Q000473:pathology*; D008264:Macrophages / Q000737:chemistry / Q000473:pathology / Q000648:ultrastructure; D009895:Opsonin Proteins / Q000378:metabolism; D011433:Propranolol / Q000494:pharmacology; D011943:Receptors, Adrenergic, beta / Q000032:analysis / Q000502:physiology; D013929:Thromboxane B2 / Q000378:metabolism*; D014407:Tumor Cells, Cultured; D001749:Urinary Bladder Neoplasms / Q000378:metabolism / Q000473:pathology / Q000648:ultrastructure; D015054:Zymosan / Q000494:pharmacology
D009895:Opsonin Proteins; D011943:Receptors, Adrenergic, beta; D013929:Thromboxane B2; D005480:Flurbiprofen; D015054:Zymosan; D011433:Propranolol; D007545:Isoproterenol