Krebs solution consisted of NaCl 117 mM, NaHCO3 25 mM, KCl 4.7 mM, CaCl2 2.5 mM, MgSO4 1.2 mM, KH2SO4 1.2 mM, glucose 11.1 mM, and ascorbic acid 0.28 mM. In calcium-free Krebs solution, 2.5 mM CaCl2 was removed without substitution. Phenylephrine hydrochloride, SNP, PAME, methyl stearate or stearic acid methyl ester (SAME), L-NG-nitroarginine (L-NNA), indomethacin, miconazole, SKF525A, and tetraethylammonium (TEA) were from Sigma-Aldrich; glibenclamide and iberiotoxin were from Tocris (Ellisville, MO), and 4-aminopyridine (4-AP) was from Fluka (St. Louis, MO); hexane was from J.T. Baker (Phillipsburg, NJ). PAME was dissolved in absolute methanol and then diluted with Krebs solution to a final methanol concentration of <0.1% vol/vol. L-NNA was dissolved in acidified normal saline; indomethacin, miconazole, 4-AP, and glibenclamide were dissolved in dimethyl sulfoxide, and SNP, TEA, iberiotoxin and SKF525A were dissolved in distilled water.