lec17-16 - Step 3 cAMP activates a cAMP-dependant protein...

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KIN 205: Chapter 14, Cardiovascular Physiology: E.3 Action of epinephrine and norepinephrine on striated myocardial cells: Step 1. Upon binding of the hormone onto its receptor ( β -adrenergic), conformational changes of the receptor lead to activation of a G-protein (Gs). Step 2. The activated G-protein triggers: 1. The opening of slow Ca 2+ channels (entry of Ca 2+ ), 2. The activation of a primary effector (adenylyl cyclase): ATP b cAMP.
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Unformatted text preview: Step 3. cAMP activates a cAMP-dependant protein kinase which in turns phosphorylates three distinct proteins: 1. Slow Ca 2+ channels, which result in their opening (entry of Ca 2+ ), 2. A sarcoplasmic reticulum protein that triggers the ATP-dependent Ca 2+ uptake, 3. Myosin which results in an increased rate of the cross-bridge cycle. The end result is an increased velocity of contraction. Figure 14-30...
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