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Epinephrine at Work
How epinephrine/norepinephrine work on cardiac mysoties themselves
Question | Answer |
---|---|
STEP 1 | Binding of epinephrine/norepinephrine changes shape of beta receptor -> activates G-Protein |
STEP 2 | G-Protein subunit activates adenylate cyclase |
STEP 3 | Adenylate cyclase catalyzes conversion of ATP to cAMP |
STEP 4 | cAMP activates protein kinase A |
STEP 5 | Protein kinase phosphorylates Calcium channels, influx on calcium in cell, stimulates contraction |
STEP 6 | protein kinase also phosphorylates calcium channels on sarcoplasmic reticulum. calcium then moves into the cytoplasm and stimulates contraction. |
STEP 7 | Protein kinase phosphorylates myosin, stimulates contraction |
STEP 8 | Protein kinase phosphorylates sarcoplasmic Calcium ATPase -> speeds removal of calcium from cytoplasm during relaxtion. decreases over relaxtion time. |