[Increased [3H] PN 200-110 binding sites in the myocardial sarcolemmal membrane in endotoxin shock rats].
To study the effects of endotoxin shock on calcium channels of sarcolemma, we investigated the characteristics of binding of a radioligand, [3H] PN 200-110 (PN), to relatively pure sarcolemmal membrane (SL) from the heart of endotoxin shock rats. The rats were induced into endotoxin shock with the cecal ligation and puncture. The SL of the early group (EG), in hyperdynamic stage, was isolated from the rat's heart, 9 hours after the procedure, and that of late group (LG), in hypodynamic stage, was isolated from the rat's heart, 18 hours after the procedure. Binding of PN to SL of EG was 31-37% greater than to SL of the sham operated rat (CG), while binding of PN to SL of LG was not raised significantly, as compared to that to CG. The maximum number of PN binding sites (Bmax) was 35% higher in SL of EG than in SL of CG, but there was no significant difference between Bmax in SL of LG and CG. On the other hand, the affinity for PN binding (KD) was similar in all three groups. Since PN binding sites are considered to be specific sites for the voltage-dependent Ca2+ channels of sarcolemma, it is concluded that the density of these channels in the sarcolemma of rat increases during the early stage of endotoxin shock and decreases to control level in the late stage of the shock.
Motoyama
Y
Y
Department of Anesthesiology, Juntendo University School of Medicine, Tokyo.
D000818:Animals; D001665:Binding Sites; D002121:Calcium Channel Blockers / Q000378:metabolism*; D015220:Calcium Channels / Q000378:metabolism; D066298:In Vitro Techniques; D008297:Male; D009206:Myocardium / Q000166:cytology / Q000378:metabolism*; D011869:Radioligand Assay; D051381:Rats; D012508:Sarcolemma / Q000378:metabolism*; D012772:Shock, Septic / Q000378:metabolism*
D002121:Calcium Channel Blockers; D015220:Calcium Channels