55] Parietal cell preparation and arachidonate metabolism

Abstract

The chapter presents a study on parietal cell preparation and arachidonate metabolism. The chapter utilizes and describes a procedure in detail that separates the gastric cells using two consecutive Percoll gradients, the first discontinuous and the second continuous. The first is a discontinuous gradient of densities 1.04, 1.065, and 1.09 g/ml. The second gradient is a continuous gradient prepared from 44% Percoil in Hanks' balanced salt solution (HBSS). In addition, the technique utilizes sieving through a series of 100% polyamide nylon fibers of different pore size to remove cell clumps. Prostaglandins (PG) E 2 and I 2 , and arachidonic acid have been found to be potent inhibitors of histamine-stimulated acid production in isolated canine parietal cell-enriched preparations. Prostaglandin inhibition in vivo results in enhanced acid secretory response to histamine and pentagastrin suggesting that mucosal prostaglandins have a modulatory role in acid production. A highly enriched parietal cell preparation is necessary when examining the parietal cell synthesis of other eicosanoids, such as leukotrienes to minimize eicosanoid contamination by other cells. In conclusion, the parietal cell-enriched preparation has allowed the examination of the cellular and intracellular mechanism of action of prostaglandins, as well as the regulation of their production.