Role of nitric oxide in the regulation of oxygen consumption in conscious dogs

Abstract

The role of nitric oxide (NO) in the regulation of O2 consumption was studied in chronically instrumented conscious dogs. A specific NO synthesis inhibitor, nitro-L-arginine (NLA, 30 mg/kg IV), significantly increased mean arterial pressure from 100±4 to 134±5 mm Hg (mean±SEM) and total peripheral resistance by 157±16% and reduced cardiac output by 47±3% and heart rate by 34±6% after 120 minutes. Changes in arterial blood gases were not observed. There were significant changes in PO2 (-14±2 mm Hg), O2 saturation (-21±2%), the percentage of hemoglobin as oxyhemoglobin (- 21±2%), and O2 content (-3.0±0.9 vol%) and a significant increase in percent reduced hemoglobin (21±1%) in mixed venous blood, associated with an increase in O2 extraction (5.1±0.2 vol%) (all P