Leukotrienes C4 and D4 potentiate acid production by isolated rat parietal cells

Abstract

The effects of leukotrienes (LTs) B4, C4, and D4 on acid production by enriched (80%–85%) rat parietal cells were investigated. Acid production was indirectly measured by [14C]aminopyrine uptake into the cells. Leukotriene B4 (10−10–10−6 mol/L) had no effect on basal or prestimulated [14C]aminopyrine uptake. Leukotriene C4 and LTD4 (10−10–10−6 mol/ L) also did not change basal acid production but potentiated prestimulated [14C]aminopyrine uptake. Maximal effects were observed with 1 × 10−7 mol/L LTC4 or with 3 × 10−7 mol/L LTD4. At these concentrations LTC4 and LTD4 induced the indicated increases above the responses to the following prestimulants (= 100%): 10−4 mol/L histamine (71% and 74%, respectively), 10−5 mol/L forskolin (54% and 106%), 10−4 mol/L dibutyryl cyclic adenosine monophosphate (34% and 81%), and 10−4 mol/L carbamylcholine (160% and 116%). Yet, adenosine triphosphate (2.5−5 × 10−3 mol/L)-induced [14C]aminopyrine uptake in digitonin-permeabilized parietal cells was not further increased by LTC4 or LTD4. At 10−5 mol/L the selective LTD4 antagonist L-660,711 (MK-571) reduced the effect of 3 × 10−7 mol/L LTD4 by 74% but had no effect on the potentiation by LTC4. We conclude that the sulfidopeptide LTs C4 and D4, but not LTB4, exert a direct effect on rat parietal cells, and that this effect seems to be mediated by separate specific receptors. Leukotriene C4 and LTD4 potentiate prestimulated H+ formation by interacting with an intracellular mechanism that is commonly activated upon occupation of histamine H2- as well as muscarinic receptors, and that is also activated by the postreceptor stimuli forskolin and dibutyryl cyclic adenosine monophosphate; yet, this mechanism seems to be localized proximal to the H+, K+-adenosine triphosphatase.