Mechanisms involved in the swelling of erythrocytes caused by Pacific and Caribbean ciguatoxins.
The mechanisms underlying the swelling of frog red blood cells (RBC), induced by Pacific (P-CTX-1) and Caribbean (C-CTX-1) ciguatoxins (CTXs), were investigated by measuring the length, width and surface of their elliptic shape. P-CTX-1 (0.5 to 5 nM) and C-CTX-1 (1 nM) induced RBC swelling within 60 min. The CTXs-induced RBC swelling was blocked by apamin (1 microM) and by Sr(2+) (1 mM). P-CTX-1-induced RBC swelling was prevented and inhibited by H-[1,2,4]oxadiazolo[4,3-a]quinoxalin-1-one (27 microM), an inhibitor of soluble guanylate cyclase (sGC), and NOS blockade by NG methyl-l-arginine (l-NMA; 10 microM). Cytochalasin D (cytD, 10 microM) increased RBC surface and mimicked CTX effect but did not prevent the P-CTX-1-induced l-NMA-sensitive extra increase. Calculations revealed that P-CTX-1 and cytD increase RBC total surface envelop and volume. These data strongly suggest that the molecular mechanisms underlying CTXs-induced RBC swelling involve the NO pathway by an activation of the inducible NOS, leading to sGC activation which modulates intracellular cGMP and regulates L-type Ca(2+) channels. The resulting increase in intracellular Ca(2+) content, in turn, disrupts the actin cytoskeleton, which causes a water influx and triggers a Ca(2+)-activated K(+) current through SK2 isoform channels.
Sauviat
Martin-Pierre
MP
Laboratoire d'Optique et Biosciences, INSERM U696, UMR CNRS 7645, X/ENSTA, Ecole Polytechnique, route de Saclay, 91128 Palaiseau Cedex, France. martin-pierre.sauviat@polytechnique.fr
Boydron-Le Garrec
Raphaële
R
Masson
Jean-Baptiste
JB
Lewis
Richard L
RL
Vernoux
Jean-Paul
JP
Molgó
Jordi
J
Laurent
Dominique
D
Benoit
Evelyne
E
D000199:Actins / Q000378:metabolism; D000818:Animals; D002118:Calcium / Q000378:metabolism; D020746:Calcium Channels, L-Type / Q000378:metabolism; D002463:Cell Membrane Permeability / Q000187:drug effects*; D048429:Cell Size / Q000187:drug effects*; D002922:Ciguatoxins / Q000633:toxicity*; D006152:Cyclic GMP / Q000378:metabolism; D003599:Cytoskeleton / Q000378:metabolism; D004791:Enzyme Inhibitors / Q000494:pharmacology; D004910:Erythrocyte Membrane / Q000187:drug effects / Q000201:enzymology* / Q000473:pathology; D006162:Guanylate Cyclase / Q000037:antagonists & inhibitors / Q000378:metabolism*; D052247:Nitric Oxide Synthase Type II / Q000037:antagonists & inhibitors / Q000378:metabolism*; D011893:Rana esculenta; D014867:Water / Q000378:metabolism
D000199:Actins; D020746:Calcium Channels, L-Type; D004791:Enzyme Inhibitors; D014867:Water; D002922:Ciguatoxins; D052247:Nitric Oxide Synthase Type II; D006162:Guanylate Cyclase; D006152:Cyclic GMP; D002118:Calcium