Role of Ca2(+)-calmodulin and protein kinase C in the secretory action of heat-labile enterotoxin of Escherichia coli in mice.
The mucosal-to-serosal and serosal-to-mucosal fluxes of Na+ and Cl- were carried out in control and heat-labile enterotoxin treated mice in the presence or absence of Ca2(+)-ionophore A23187, the activator of Ca2(+)-calmodulin or Phorbol-12-myristate-13-acetate (PMA), the activator of Protein kinase C (PKC) or 1-(5-isoquinolinyl sulphonyl)-2-methyl piperazine (H-7), an inhibitor of PKC. There was net secretion of Na+ and Cl- in experimental group in comparison to net absorption in control group. The addition of ionophore or PMA resulted in net secretion of Na+ and Cl- in control group. In experimental group ionophore increased the net secretion of Na+ and Cl- while, PMA could not cause any change in Na+ and Cl- fluxes in experimental group. Calmodulin activity remained unaltered in heat-labile enterotoxin treated mice as compared to control. H-7, reversed the effects of PMA and heat-labile enterotoxin. These studies demonstrate that heat-labile enterotoxin primarily involves PKC in its action.
Goyal
J
J
Department of Pediatrics, Postgraduate Institute of Medical Education and Research, Chandigarh, India.
Ganguly
N K
NK
Garg
U C
UC
Walia
B N
BN
D000818:Animals; D002135:Calcium-Binding Proteins / Q000494:pharmacology; D002147:Calmodulin / Q000502:physiology*; D002713:Chlorine / Q000378:metabolism; D004768:Enterotoxins / Q000502:physiology*; D004926:Escherichia coli / Q000378:metabolism; D007419:Intestinal Secretions; D007422:Intestines / Q000166:cytology; D051379:Mice; D008871:Microvilli / Q000378:metabolism; D011493:Protein Kinase C / Q000502:physiology*; D012964:Sodium / Q000378:metabolism; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology; D014268:Trifluoperazine / Q000494:pharmacology
D002135:Calcium-Binding Proteins; D002147:Calmodulin; D004768:Enterotoxins; C025673:calciphorin; D014268:Trifluoperazine; D002713:Chlorine; D012964:Sodium; D011493:Protein Kinase C; D013755:Tetradecanoylphorbol Acetate