Ca dependence of Na influx during treatment of rabbit aorta with NE and high K solutions.

摘要: Cellular influx of 24Na was measured in isolated rabbit aorta during stimulation with 10 microM norepinephrine (NE) or depolarization 80 mM K solution, using a pulse-labeling, cold-wash technique. NE caused two- to threefold increase Na influx; smaller but significant also observed depolarized tissues. Basal and NE-induced fluxes at 1 min were significantly increased by 20-min preincubation Ca-free solution containing 2 EGTA; elevation [Mg] this reduced these effects. The high K-induced prevented combination low Ca (30 microns) elevated Mg (10 mM). agonist, BAY-K 8644, influx. antagonist, diltiazem, inhibited the depolarization-stimulated concentration-dependent manner, less effective blocking response NE. Extension plus medium from 30 s 15 decreased contraction. After exposure remained after washing out continued absence Ca. A second that time did not We propose component excitation depends directly on rise intracellular [Ca]. role an indirect effect [Ca] metabolic H+ production subsequent Na+-H+ exchange may be factor.