Leukotrienes stimulate pepsinogen secretion from guinea pig gastric chief cells by a nitric oxide-dependent pathway

Leukotrienes (LTs) are involved in many inflammatory conditions including gastric damage induced by nonsteroidal anti-inflammatory drugs. Although LTs stimulate acid secretion, the effect they exert on pepsinogen secretion is unknown. The aim of this study was to investigate whether LTs stimulate pepsinogen secretion by isolated chief cells and to identify the intracellular messengers that mediate this action. Isolated chief cells were incubated with concentrations of LTB₄, LTC₄, LTD₄, or LTE₄ ranging from 0.1 pmol/L to 10 μmol/L, and pepsinogen release, intracellular calcium and inositol(1,4,5)-trisphosphate (IP₃) concentrations were measured. Nitric oxide generation was determined by the amount of citrulline generated during incubation. All four LTs caused a concentration-dependent stimulation of pepsinogen secretion with 50% effective concentration of 0.05-0.1 nmol/L and a dose-dependent increase in cytoplasmic free calcium and IP₃ concentration. The LTB₄ and LTD₄ antagonists caused selective, concentration-dependent inhibition of LTB₄- and LTD₄-induced pepsinogen secretion, calcium mobilization, and IP₃ generation. All four LTs increased NO generation, and the effect was inhibited by LTB₄ and LTD₄ antagonists and an NO synthase inhibitor N^G-monomethyl-l-arginine and reversed by l-arginine. N^G-monomethyl-l-arginine caused a 50%–60% reduction of LT-induced pepsinogen release. Each of the four LTs caused a fivefold increase in 5′-cyclic guanosine monophosphate. LTs are powerful stimulators of pepsinogen secretion in isolated chief cells and act via occupancy of specific cell-surface receptors.