Platelet arachidonate metabolism and platelet function in zinc-deficient rats

To determine the effect of zinc status on arachidonate metabolism and the initiation of aggregation by a prostaglandin endoperoxide analog (U-44069), immature rats were fed for 5 days a low zinc (less than 1 ppm) or control (100 ppm Zn) diet based on soybean protein. In vitro production of thromboxane B2 (TXB2) by platelet-rich plasma after stimulation by either arachidonate (0.2 mM) or ADP (0.2 microM) was not changed by dietary zinc deprivation, even though bleeding time was prolonged. Oxygenation of exogenous arachidonate, catalyzed by either the cyclooxygenase or lipoxygenase pathway, was not affected by zinc deficiency. Platelet aggregation in response to the prostaglandin endoperoxide analog at both 8 and 16 microM was impaired by dietary zinc deprivation. While short-term zinc deprivation decreased platelet response to minimal levels of aggregating agents, production of arachidonate metabolites was unimpaired. It is postulated that platelet response to the products of arachidonate metabolism is reduced.