Biological Actions

A few biologically important systems will be discussed that emphasize the importance of prostaglandin relatives. At this point it is useful to examine the signal transduction of prostanoid receptors. Receptors involved in the contraction of smooth muscle, EPi, EP3, FP, and TP receptors, generally require an elevation of Ca2+ free in the cytoplasm. Some of these systems may involve the opening of Ca2+ channels operated by the activated receptor. Cytoplasmic Ca2+ levels can increase by an influx of Ca2+ through opened Ca2+ channels or by the mobilization of intracellular stores through the activation of the phosphati-dylinositol system and the generation of IP3 or both. It is possible that some receptors, EP3 for example, can be coupled to different transducing systems in different tissues.

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