PHSI 208 Lecture Notes - Lecture 23: Serca, Cardiac Muscle Cell, Cardiac Muscle
Document Summary
Although removal of ca2+ to extracellular space is slightly more important in cardiac muscle, reuptake into the sr is still the primary mechanism. In skeletal muscle, the bulk/most of the ca2+ signal comes from the sr. Serca pump is regulated by phospholamban (pln) in cardiac muscle. In skeletal muscle, the serca pump is always active and available to pump ca2+ back into the sr. The pln protein has to be phosphorylated for the serca pump to function properly. If pln is not phosphorylated, serca pump is inhibited and ca2+ will return slowly back to the sr: phosphorylated pln, increases serca pump activity, increasing ca2+ reuptake. Phosphorylation of pln is by the sympathetic ns. There"s al(cid:449)ays some level of autonomic activation of the cardiac muscle: active sympathetic state has many phosphorylated pln and high activity in the. Ca2+: cardiac muscle is capable of graded single twitch contractions (not always the same amount of tension)
