[Intracellular Ca2+ homeostasis in the smooth muscle and functional role of calcium pump in the sarcolemma].
It has been found that Ca-pump of the smooth muscle sarcolemma has much greater affinity to Ca2+ (Km = 0.5 M) than the system Na-Ca2+ of the exchanger (Km = 40-60 M). The maximal rate of Mg2+, ATP-dependent translocation of Ca2+ is 2-3 times higher than that of Na-dependent. The results of kinetic analysis show that Ca-pump of the smooth muscle sarcolemma is able to compensate the basal diffusion flow of this cation entering into unexcited cells of smooth muscle (5 x 10(-15) mol Ca2+ per 1 cm2 for 1 sec). It can also stationary support the value of Ca2+ concentration in relaxed myocytes on a physiologically significant level (10(-7)-10(-6) M).
Kosterin
S A
SA
Kurskiĭ
M D
MD
Burchinskaia
N F
NF
D000818:Animals; D001692:Biological Transport; D002118:Calcium / Q000378:metabolism*; D002417:Cattle; D006706:Homeostasis; D007700:Kinetics; D009130:Muscle, Smooth / Q000378:metabolism*; D012508:Sarcolemma / Q000378:metabolism*
D002118:Calcium
Vnutrikletochnyĭ gomeostaz Ca2+ v gladkoĭ myshtse i funktsional'naiarol' kal'tsievogo nasosa sarkolemmy.