the excitability of short segments ( 5-7 mm ) of bundles of canine purkinje fibers was depressed by exposure to 15-18 mm k ( + ) , to 15-18 mm k ( + ) plus 5 x 10 ( -6 ) epinephrine or norepinephrine , to low k ( + ) , and to low na ( + ) .
C0014563
epinephrine
C0028351
norepinephrine