[Effect of caffeine on active Ca2+ ion transport in a homogenate of skeletal muscles and myocardium].
A Ca2-selective electrode was used to study active transport of Ca2+ by sarcoplasmic reticulum fragments of rabbit skeletal muscle and myocardium homogenates. The specific Ca2+ transport activities (mumol Ca2+/min/mg tissue) are 40 = 60 and 3 = 5 units for fast and slow muscles and the myocardium, respectively. Caffeine (5 mM) exerts a powerful inhibitory influence on Ca2+ transport in skeletal muscle homogenates. For fast muscles, the degree of inhibition exceeds 50%. The rate of Ca2+ transport in the myocardium homogenate increases in the presence of creatine phosphate. The latter produces no effect on Ca2+ transport in skeletal muscle homogenates. The high sensitivity of Ca2 transport to caffeine, a specific blocker of Ca2+ transport to the terminal cisterns of the sarcoplasmic reticulum, suggests that the terminal cisterns, apart from being a reservoir for Ca2+ needed for contraction trigger, may play an essential role in muscle relaxation.
D000818:Animals; D001693:Biological Transport, Active / Q000187:drug effects; D002110:Caffeine / Q000494:pharmacology*; D002118:Calcium / Q000378:metabolism*; D002413:Cations, Divalent; D003864:Depression, Chemical; D006321:Heart / Q000187:drug effects*; D009132:Muscles / Q000187:drug effects* / Q000378:metabolism; D009206:Myocardium / Q000378:metabolism*; D011817:Rabbits; D012519:Sarcoplasmic Reticulum / Q000187:drug effects / Q000378:metabolism
D002413:Cations, Divalent; D002110:Caffeine; D002118:Calcium
Vliianie kofeina na aktivnyĭ transport ionov Ca2+ v gomogenate skeletnykh myshts i miokarda.