Thromboxane physiological actions

The functional significance of thromboxane A2 inhibition by kava is not certain. More needs to be understood about the functions of prostaglandins in the CNS, but given the inhibition of GABAA by thromboxane A2, kava s suppression of thromboxane A2 synthesis could conceivably contribute to its anxiolytic and sedative effects. More research is needed to determine if this mechanism of action is physiologically significant at normal kavalactone concentrations. 

By 1976, Vane and associates had identified another prostanoid compound, prostacyclin (or PCl2). This compound also arises from PGHj by action of a cytochrome P450-like prostacyclin S3mthase (Fig. 21-7). It is thought to be an important vasoprotective molecule. As with the thromboxanes, prostacyclin undergoes rapid inactivation by hydrolysis to the physiologically inactive 6-0x0-PCF a. 

The discovery of the prostaglandin endoperoxides and thromboxane Aj, compounds with pronounced biological activity but short half-life under physiological conditions, initiated a search for stable synthetic compounds that mimic the actions of the labile arachidonate metabolites. Several of these synthetic compounds are structural analogues to PGH2. 

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