This investigation examined the hypothesis that release of K(+) accounts for EDHF activity by comparing relaxant responses produced by ACh and KCl in human subcutaneous resistance arteries. Resistance arteries (internal diameter 244+/-12 microm, n=48) from human subcutaneous fat biopsies were suspended in a wire myograph. Cumulative concentration-response curves were obtained for ACh (10(-9) - 3x10(-5) M) and KCl (2.5 - 25 mM) following contraction with noradrenaline (NA; 0.1 - 3 microM). ACh (E(max) 99.07+/-9.61%; -LogIC(50) 7.03+/-0.22; n=9) and KCl (E(max) 74.14+/-5.61%; -LogIC(50) 2.12+/-0.07; n=10)-induced relaxations were attenuated (P
