Polylysine-induced rapid Ca2+ release from cardiac sarcoplasmic reticulum.
The rapid kinetics of polylysine-induced Ca2+ release from cardiac sarcoplasmic reticulum (SR) was assessed in combination with its effect on ryanodine binding. SR vesicles were isolated from canine cardiac SR. The time course of SR Ca2+ release was continuously monitored by a stopped-flow apparatus, and [3H]ryanodine binding was done by using the filtration method. The initial rate of polylysine-induced Ca2+ release from cardiac SR revealed different concentration dependence from those observed in skeletal SR. The initial rate peaked at 0.11 microM, followed by a decrease at higher concentrations in skeletal SR, whereas it increased to 3.7 microM in cardiac SR. The [3H]ryanodine binding was also stimulated by polylysine with an identical parallelism with Ca2+ release in terms of polylysine concentration dependence. Thus we demonstrated that the cardiac SR Ca2+ release channel is sensitive to activation by polylysine and that there is a difference in the concentration dependence of polylysine-induced activation of cardiac and skeletal SR Ca2+ release channels.
Second Department of Internal Medicine, Yamaguchi University School of Medicine, Ube, Japan.
M
M
Yano
T
T
Yamamoto
M
M
Kohno
T
T
Hisaoka
K
K
Ono
T
T
Tanigawa
T
T
Ueyama
T
T
Ohkusa
M
M
Matsuzaki
D000818:Animals; D002118:Calcium / Q000378:metabolism*; D004285:Dogs; D005470:Fluorometry; D006321:Heart / Q000187:drug effects; D066298:In Vitro Techniques; D007700:Kinetics; D009206:Myocardium / Q000378:metabolism*; D011107:Polylysine / Q000494:pharmacology*; D012433:Ryanodine; D012519:Sarcoplasmic Reticulum / Q000187:drug effects / Q000378:metabolism*
D012433:Ryanodine; D011107:Polylysine; D002118:Calcium