NASA Logo

NTRS

NTRS - NASA Technical Reports Server

Back to Results
Specialized physiological studies in support of manned space flightThe effects of a diuretic (Lasix) induced dehydration on the cardiovascular and hematological responses to lower body negative pressure (LBNP) were analyzed and compared to previous observations on dehydration following exercise in the heat. During LBNP runs the subjects were monitored for changes in blood volume, heart rate, blood pressure, and variations in the volume of the left calf. It was concluded that Lasix dehydration produced a depletion of the body electrolytes at the expense of both the plasma and extravascular compartments. Striking differences were found between those subjects who were physically active (Runners: R) and those who did not engage in any regular physical activity (Non-runners: NR). Tolerance to LBNP (Torr x min) was significantly lower in the R's than the NR's before and after dehydration, however the R's lost more of their tolerance after dehydration with Lasix than after exercise in the heat for about the same fluid loss. The opposite was true for the NR's. Two factors appear to be responsible for the lower LBNP tolerance in R's: parasympathetic inhibition of cardiac activity during LBNP and a greater propensity to pool blood in the lower extremities.
Document ID
19790008371
Acquisition Source
Legacy CDMS
Document Type
Contractor Report (CR)
Authors
Luft, U. C.
(Lovelace Foundation for Medical Education and Research Albuquerque, NM, United States)
Loeppky, J. A.
(Lovelace Foundation for Medical Education and Research Albuquerque, NM, United States)
Venters, M. D.
(Lovelace Foundation for Medical Education and Research Albuquerque, NM, United States)
Kobayashi, Y.
(Lovelace Foundation for Medical Education and Research Albuquerque, NM, United States)
Date Acquired
September 3, 2013
Publication Date
December 1, 1978
Subject Category
Aerospace Medicine
Report/Patent Number
NASA-CR-151876
Accession Number
79N16542
Funding Number(s)
CONTRACT_GRANT: NAS9-15483
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.
No Preview Available