Single-Channel Mechanism of .BETA.-Adrenergic Enhancement of Cardiac L-Type Calcium Current.

摘要: The cardiac L-type Ca2+ channel current is enhanced by beta-adrenergic stimulants phosphorylation mediated an increase in cyclic AMP. Single-channel studies have revealed that the channels are not always allowed to open at test steps from large negative holding potentials and beta-agonists ratio of current-containing sweeps (availability, Ps). duration available (Ts) unavailable states (TF) measurable applying a number pulses. beta-Agonists shorten TF prolong TS, possibly enhancing activating AMP-dependent protein kinase inhibiting dephosphorylation phosphorylating phosphatase inhibitor 1, respectively, if state reflects phosphorylated channel. modulation slow gating process, PS, plays primary role increasing moderate sympathetic activity. When larger AMP resulted, moduration burst-kinetics including mode 2 openings also produced enhances further current.