Human cardiovascular reactions to simulated hypovolaemia, modified by the opiate antagonist naloxone

• Published in: European journal of applied physiology and occupational physiology Vol. 57; no. 4; p. 507
• Main Authors: Foldager, N, Bonde-Petersen, F
• Format: Journal Article
• Language: English
• Published: Germany 01.03.1988
• Subjects: Adult; Blood Pressure - drug effects; Blood Volume; Cardiovascular System - drug effects; Heart Rate - drug effects; Humans; Lower Body Negative Pressure; Male; Naloxone - pharmacology; Narcotic Antagonists; Systole; Time Factors
• ISSN: 0301-5548
• DOI: 10.1007/BF00418000

Six healthy males were exposed to 20 mm Hg lower body negative pressure (LBNP) for 8 min followed by 40 mm Hg LBNP for 8 min. Naloxone (0.1 mg.kg-1) was injected intravenously during a 1 h resting period after which the LBNP protocol was repeated. Systolic, mean, and diastolic arterial blood pressures (SAP, MAP, DAP), and central venous pressure (CVP) were obtained using indwelling catheters. Cardiac output (CO), forearm blood flow (FBF), heart rate (HR), left ventricular ejection time (LVET), and electromechanical systole (EMS) were measured non-invasively. Pulse pressure (PP), stroke volume (SV), total peripheral resistance (TPR), forearm vascular resistance (FVR), systolic ejection rate (SER), pre-ejection period (PEP), PEP/LVET and indices for the systolic time intervals (LVETI, EMSI, PEPI) were calculated. During the second LBNP exposure, only two parameters differed from the pre-injection values: DAP at LBNP = 40 mm Hg increased from 60.0 +/- 4.8 mm Hg to 64.8 +/- 4.1 mm Hg (N = 4, p less than 0.02) and LVETI at LBNP = 20 mm Hg increased from 384.4 +/- 5.2 ms to 396.8 +/- 6.2 ms (N = 6, p less than 0.02).