Mastoparan increases membrane permeability in rat parotid cells independently of action on G-proteins.
Mastoparan, a peptide toxin from wasp venom, stimulated the accumulation of inositol phosphates in rat parotid acinar cells. Addition of this peptide to fura-2-loaded cells resulted in a rapid increase in the fura-2 fluorescence ratio (340 nm/380 nm), suggesting that mastoparan stimulates an increase in cytosolic Ca2+ concentration. However, this change in the ratio appears to be due, in part, to fura-2 leakage from the cells, because addition of Mn2+, which quenches extracellular fura-2 fluorescence, reduced the increased fluorescence ratio. In addition to the fura-2 leakage, mastoparan caused considerable leakage of lactate dehydrogenase, a cytosolic marker enzyme. Furthermore, mastoparan decreased the number of trypan blue-excluding cells, indicating a decrease in cell viability. These results suggest that mastoparan enhances the membrane permeability by a mechanism independent of the activation of G-proteins.
Tanimura
A
A
Department of Dental Pharmacology, School of Dentistry, Higashi-Nippon-Gakuen University, Hokkaido, Japan.
Matsumoto
Y
Y
Tojyo
Y
Y
D000818:Animals; D015415:Biomarkers; D002118:Calcium / Q000378:metabolism; D002463:Cell Membrane Permeability / Q000187:drug effects*; D003600:Cytosol / Q000378:metabolism; D016257:Fura-2 / Q000494:pharmacology; D019204:GTP-Binding Proteins / Q000187:drug effects / Q000378:metabolism*; D006868:Hydrolysis; D007295:Inositol Phosphates / Q000378:metabolism; D036341:Intercellular Signaling Peptides and Proteins; D007770:L-Lactate Dehydrogenase / Q000378:metabolism; D008297:Male; D010306:Parotid Gland / Q000187:drug effects / Q000378:metabolism*; D010455:Peptides; D051381:Rats; D011919:Rats, Inbred Strains; D014862:Wasp Venoms / Q000494:pharmacology*
D015415:Biomarkers; D007295:Inositol Phosphates; D036341:Intercellular Signaling Peptides and Proteins; D010455:Peptides; D014862:Wasp Venoms; C037500:mastoparan; D007770:L-Lactate Dehydrogenase; D019204:GTP-Binding Proteins; D002118:Calcium; D016257:Fura-2