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

Abstract

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.

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