‘In vivo’ studies on the pathophysiological mechanism of Vibrio parahaemolyticus TDH+—induced secretion

Abstract The thermostable direct haemolysin (TDH) is considered to be the major virulence factors of Vibrio parahaemolyticus ; however, poor information is available about its mechanism of action. In our study we examined the capacity of two V. parahaemolyticus TDH-producers (strains 2067 and 3305) to induce fluid secretion in rat ileal loop and to reveal the role of calcium ions (Ca 2+ ), calmodulin (CaM), and protein kinase C (PKC) in V. parahaemolyticus TDH + -induced fluid secretion. The results show that V. parahaemolyticus TDH + strains were able to induce secretion in small intestine; on the contrary, this ability was not evidenced in the V. parahaemolyticus TDH − strain used as negative control. The data suggest an enterotoxic activity of haemolysin. Calcium ionophore A23187 and 1-verapamil (calcium channel blocker), when injected alone, induced fluid accumulation in the control loops. A further increase in fluid accumulation ( P + strains and a significant decrease ( P Our findings suggest that Ca 2+ appears to be an important messenger involved in the stimulation of intestinal secretion, contrary to PKC and calmodulin which do not appear to have any role.