Fig. 1.
Testosterone (TES)-induced coronary artery relaxation requires nitric oxide (NO)-stimulated large-conductance, calcium-activated potassium (BKCa) channel activity. A: representative traces of TES (25 μM)-induced maximal relaxation of endothelium-denuded coronary arteries precontracted with 10 μM prostaglandin F2α (PGF2α), in the presence or absence of iberiotoxin (20 nM; 30 min). The period of drug exposure is indicated by the line above the tracing or by arrow. B: typical BKCa channel recordings from the same cell-attached patch on a porcine coronary artery smooth muscle (CASM) cell (+40 mV) before (con) and 20 min after exposure to 100 nM TES and then after cumulative addition of 20 μM NG-monomethyl-l-arginine (l-NMMA) and 500 μM 8-bromo (Br)-cGMP. Channel openings are upward deflections from the baseline (closed) state, indicated by dashed line (c). The opening level amplitude of a single BKCa channel is indicated by the dashed line at open level 1 (O1), whereas simultaneous opening of 2 channels is indicated by the dashed line at open level 2 (O2).