The biosynthesis and metabolism of prostaglandins.

With improved techniques for isolation and identification of materials, thromboxane (TXA2) and prostacyclin (PGI2) derivatives are now recognized as more abundant in some tissues and more potent than PGE2 and PGF2alpha. The rapid appearance and disappearance of these autacoids can be regulated at many points along the enzymatic path. Two important features affecting the rate of overall prostaglandin formation are the availability of non-esterified substrate and the availability of hydroperoxide activator for the cyclooxygenase. The fate of the endoperoxide formed by this reaction then depends upon the different relative amounts of the synthases and dehydrogenases in each type of synthesizing cell. Important future developments will indicate ways in which the amounts of these enzyme activities are altered and the ways in which the prostaglandin receptors interact with cellular adenyl cyclase and adrenergic receptors.