Venous versus arterial actions of diethylamine/nitric oxide (DEA/NO) complex and S‐nitroso‐N‐acetylpenicillamine (SNAP) in vivo

1 We studied the effects of diethylamine/NO complex (DEA/NO) and S‐nitroso‐N‐acetylpenicillamine (SNAP), relative to those of sodium nitroprusside (SNP) and nitroglycerin (NTG), on mean arterial pressure (MAP), mean circulatory filling pressure (MCFP), arterial resistance (R a ), venous resistance (R v ), heart rate (HR), cardiac output (CO) and stroke volume (SV) in groups of Inactin‐anaesthetized rats pre‐treated with i.v. mecamylamine (3.7 μmol kg −1 ) and noradrenaline (6.8 nmol kg −1  min −1 ). Doses of each that reduced MAP by 30%, 80% and the lowest dose that maximally reduced MAP were examined to allow a comparison of the compounds' dilator actions at equivalent effective depressor doses. 2 DEA/NO (4, 32 and 256 μg kg −1  min −1 ), SNAP (4, 32 and 256 μg kg −1  min −1 ) and SNP (8, 32 and 128 μg kg −1  min −1 ) caused similar dose‐dependent reductions in MAP and R a , and increases in CO and SV. NTG (0.2, 0.8 and 6.4 μg kg −1  min −1 ) dose‐dependently reduced R a , and increased CO and SV, but lowered MAP only at the highest dose. 3 DEA/NO, SNAP and SNP but not NTG lowered MCFP with efficacy: DEA/NO>SNAP>SNP. All four drugs reduced R v with efficacy: DEA/NO ≈amp; SNAP>SNP ≈amp; NTG. 4 Therefore, all compounds lowered R a and R v . DEA/NO, SNAP and SNP but not NTG reduced MCFP. The pharmacological profiles of DEA/NO and SNAP resemble SNP more than NTG.British Journal of Pharmacology (1998) 125 , 1247–1251; doi: 10.1038/sj.bjp.0702175