Regulation of single calcium channels in cerebral arteries by voltage, serotonin, and dihydropyridines.

摘要: Unitary currents through Ca channels were measured from cell-attached patches on smooth muscle cells isolated rabbit cerebral (basilar) arteries. Barium (80 and 10 mM) calcium used as the charge carriers. The dihydropyridine channel agonist BAY R 5417 was to increase open-state probability (Popen), with 500 nM increasing Popen 10-fold at 0 mV. single greater than any voltage, single-channel conductances negative -20 mV of 24.6 pS mM barium), 15.1 calcium), 17.2 (10 5.8 calcium). increased 2.7-fold per 5- 7-mV membrane depolarization (negative mV) half maximal +0.4 calcium) +13.5 barium). but not barium carrier exhibited pronounced inactivation positive (half time, 112 ms mV). nimodipine (2 nM) inhibited average channels. artery constrictor serotonin by much 200-fold without an effect conductance. A second distinct amplitude unitary often observed, corresponding a conductance about one-half more commonly observed level. small-conductance-level voltage dependent, did inactivate over 0.5-s test pulses (with could be activated serotonin.