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

Abstract

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 (Ra), venous resistance (Rv), heart rate (HR), cardiac output (CO) and stroke volume (SV) in groups of Inactin-anaesthetized rats pre-treated with i.v. mecamylamine (3.7 micromol 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. DEA/NO (4, 32 and 256 microg kg(-1) min(-1)), SNAP (4, 32 and 256 microg kg(-1) min(-1)) and SNP (8, 32 and 128 microg kg(-1) min(-1)) caused similar dose-dependent reductions in MAP and Ra, and increases in CO and SV. NTG (0.2, 0.8 and 6.4 microg kg(-1) min(-1)) dose-dependently reduced Ra, and increased CO and SV, but lowered MAP only at the highest dose. DEA/NO, SNAP and SNP but not NTG lowered MCFP with efficacy: DEA/NO > SNAP > SNP. All four drugs reduced Rv with efficacy: DEA/NO approximately equal to SNAP > SNP approximately equal to NTG. Therefore, all compounds lowered Ra and Rv. DEA/NO, SNAP and SNP but not NTG reduced MCFP. The pharmacological profiles of DEA/NO and SNAP resemble SNP more than NTG.