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-nit roso-N-acetylpenicillamine (SNAP), relative to those of sodium nitropr usside (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 stro ke volume (SV) in groups of Inactin-anaesthetized rats pre-treated wit h i.v. mecamylamine (3.7 mu mol kg(-1)) and noradrenaline (6.8 nmol kg (-1) min(-1)). Doses of each that reduced MAP by 30%, 80% and the lowe st dose that maximally reduced MAP were examined to allow a comparison of the compounds' dilator actions at equivalent effective depressor d oses. 2 DEA/NO (4, 32 and 256 mu g kg(-1) min(-1)), SNAP (4, 32 and 25 6 mu g kg(-1) min(-1)) and SNP (8, 32 and 128 mu g kg(-1) min(-1)) cau sed similar dose-dependent reductions in MAP and R-a, and increases in CO and SV. NTG (0.2, 0.8 and 6.3 pg kg(-1) min(-1)) dose-dependently reduced R-a, and increased CO and SV, but lowered MAP only at the high est dose. 3 DEA/NO, SNAP and SNP but not NTG lowered MCFP with efficac y: DEA/NO > SNAP > SNP. Al four drugs reduced R-v with efficacy: DEA/N O approximate to SNAP>SNP approximate to NTG. 4 Therefore, all compoun ds 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 tha n NTG.