From: yee@trident.arc.nasa.gov (Peter E. Yee)
Newsgroups: sci.space.news
Subject: Unexpected results from life sciences mission [Release 92-125] (Forwarded)
Date: 25 Jul 92 01:10:12 GMT
Followup-To: sci.space
Organization: NASA Ames Research Center, Moffett Field, CA
Apparently-To: sci-space-news@ames.arc.nasa.gov

Paula Cleggett-Haleim
Headquarters, Washington, D.C.                      July 24, 1992
(Phone: 202/453-8400)

RELEASE: 92-125

UNEXPECTED RESULTS FROM LIFE SCIENCES MISSION

	Scientists report dramatic changes from space travel in some of
the body's systems, with a resiliency in others -- all of which
affect long stays in space and medical research on Earth.  These
results are from the Spacelab Life Sciences-1 (SLS-1) mission, flown
aboard Space Shuttle Columbia in June 1991.

	"Taken together, these results show the need for a laboratory
in space to complement the traditional laboratory on Earth.  This is
vital in understanding how the human body works, whether it is in
space or on Earth," says Dr. Ronald White, chief scientist of NASA's
Life Sciences Division.

	Four principal investigators from the SLS-1 mission report key
findings in the areas of cardiovascular (heart and lungs),
musculoskeletal (muscles and bones) and neurovestibular (inner
ear/brain) physiology.

CARDIOVASCULA

	Space travel presents a drastic change in working conditions to
the heart and lungs, according to Dr. C. Gunnar Blomqvist, a
cardiologist from the University of Texas Health Science Center in
Dallas.

        Often astronauts just returning from space have difficulty maintaining 
normal blood pressure and blood flow when standing.  One SLS-1 experiment 
using a catheter inserted preflight into an arm vein of an astronaut and later 
moved nearer to the heart shows the astronaut experienced much more rapid fall 
in central blood pressure than was predicted.

        In another area of cardiovascular research, it was found that exposure 
to space impairs an astronaut's pressure regulating reflexes, called 
baroreflexes, according to Dr. Dwain L. Eckberg of the Hunter Holmes McGurie
Department of Veterans Affairs Medical Center and the Medical College of
Virginia,.

        A closely fitting neck collar (similar to a whip-lash collar) was used 
on astronauts during the SLS-1 mission to record two blood pressure sensing
areas located in the neck.

        By the eighth day of flight, astronauts had significantly faster 
resting heart rates, less maximum change of heart rate per unit of neck
pressure change and a smaller range of heart rate responses.  These changes
occurred in all astronauts studied.  The changes that developed were large and
statistically significant.

        These results validated findings obtained on Earth.  They were based 
on predictions that Dr. Eckberg made by studying subjects after prolonged
bedrest.

        This validation can lead to important studies in clinical medicine 
because studying astronauts before and after flight or by studying healthy
people before and after bedrest, provide insights into medical problems here
on Earth.

Nervous System

        In another SLS-1 experiment, there is clear evidence that the number 
of structures (synapses) used to communicate between the cells of the inner
ear's gravity detecting organ and the central nervous system increase greatly
during space flight, but not in size.  Therefore, these systems should be able
to adapt to the differing gravitational environments of space, the moon and
Mars, according to Dr. Muriel D. Ross, a neuroanatomist from NASA's Ames
Research Center, Moffett Field, Calif.

        Further research in this area should also shed light on the broader 
topics of memory and learning in neural tissue and on clinical diseases of the
inner ear.

Muscles

        Following space flight, there is a significant and dramatic reduction 
in the size of all muscles needed for standing and moving, according to Dr.
Kenneth M. Baldwin, an exercise and muscle physiologist from the College of
Medicine at the University of California, Irvine.

        "Also, there is a reduced capacity of muscles to burn fat for energy 
production," says Dr. Baldwin.  "In addition, this experiment has verified 
that muscles that suport the body when we walk around on Earth change their
nature in space because they are not needed."

        Taken together, these findings suggest that properties of the skeletal 
muscle system, the largest organ system of the body, are greatly altered
during space flight.
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