Methodology in prostaglandin and thromboxane assay.
Many difficulties encountered in prostaglandin and thromboxane assay can be overcome by metabolic consideration of which compound is the best target for measurement. The following requirements must be fulfilled: the chosen compound should represent a constant and preferably major fraction of the studied pathway; it should not be formed as an artifact during collection and processing of the samples; its half-life in the biological material under study should be long; and it must be chemically stable. Our knowledge of prostaglandin metabolism now enables us to solve most assay problems for prostaglandins of the E and F type and, at least in some cases, also compounds of the D type. In general, either the 15-ketodihydro metabolites or the beta-oxidized end products thereof should be monitored; either as such or as chemically stable degradation products. In the thromboxane area, most assays have so far been directed at TxB2. The present study, however, shows that this compound is a highly unsuitable target for monitoring, since it may be formed in large amounts during sample collection. Metabolic studies indicate that an early metabolite, 11-dehydro-TxB2, is a better alternative. Quantification of this product however presents certain problems: it occurs in two different forms and the equilibrium is highly dependent on for example pH. A recently developed radioimmunoassay was employed in kinetic studies on TxB2 metabolism in the human and confirmed that 11-dehydro-TxB2 gives a more reliable picture of events than its parent compound, TXB2.
Granström
E
E
Department of Physiological Chemistry, Karolinska Institutet, Stockholm, Sweden.
D000818:Animals; D006801:Humans; D008722:Methods; D011453:Prostaglandins / Q000032:analysis* / Q000378:metabolism; D011817:Rabbits; D013929:Thromboxane B2 / Q000097:blood; D013931:Thromboxanes / Q000032:analysis* / Q000378:metabolism
D011453:Prostaglandins; D013931:Thromboxanes; D013929:Thromboxane B2