Cation flux studies of the lesion induced in human erythrocyte membranes by the thermostable direct hemolysin of Vibrio parahaemolyticus

Abstract

Vibrio parahaemolyticus, an important agent of seafood-borne gastroenteritis, expresses several putative virulence factors that could account for the disease symptoms of infected humans, namely, diarrhea, nausea, and abdominal cramps. The pathogenicity of V. parahaemolyticus correlates well with the Kanagawa phenomenon (the hemolytic ability of strains grown on Wagatsuma blood agar), implicating the thermostable direct hemolysin (TDH) as the predominant toxin responsible for pathogenicity. TDH-induced hemolysis could be inhibited by the addition of the osmolyte sorbitol to the extracellular solution, supporting the hypothesis that hemolysis occurs through colloid osmosis secondary to an increase in the cation permeability of the membrane. The effect of TDH on cation permeability was investigated by measuring K+ (congener, 86Rb+) influx into human erythrocytes in which the endogenous cation transporters had been blocked (by use of ouabain, bumetanide, and nitrendipine). TDH increased K+ influx into these cells; this increase was rapid in onset and constant in magnitude, suggesting a direct action by TDH on the membrane. The kinetics of leak generation were examined; the relationship between counts accumulated and hematocrit indicated that the TDH-induced

Cell‐free production of pore forming toxins: Functional analysis of thermostable direct hemolysin from Vibrio parahaemolyticus

“…This is a very important observation in the context of TDH induced cationic fluxes playing a major role in the diarrhetic action of Vibrio parahaemolyticus . Our observations with the cationic selective pore response clearly match to the erythrocyte model studies .…”

“…In future experiments, the influence of anions on the transmembrane current induced by TDH2 at different voltages will be studied to analyze whether TDH2 has a preferential selectivity of anions over cations. Preferential selectivity of potassium over sodium by TDH2 induced pores supports the previous hypothesis . In their study over the human erythrocyte membranes, Huntley et al has showed that TDH induced hemolysis was highly selective for potassium ions over sodium.…”

Effect of Vibrio parahaemolyticus haemolysin on human erythrocytes

“…The present study reveals that thermostable direct haemolysin from V. parahaemolyticus induces a cation channel. In earlier flux studies (Huntley et al, 1993), a sequence of Cs + > Li + > K + > Rb + > Na + has been Fig. 6.…”

Vibrio parahaemolyticus Thermostable Direct Hemolysin Modulates Cytoskeletal Organization and Calcium Homeostasis in Intestinal Cultured Cells

“…This permeabilization to calcium ions could result from the formation of pores on the cell membrane. In erythrocytes, TDH has been reported to acts as a poreforming toxin (11,13,23) causing membrane permeabilization and colloidal osmotic lysis. However, although TDH has been reported to induce calcium influx in cells other than erythrocytes (10,18,24), formation of pores in such cell lines has not been reported.…”