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Mike Mitka

JAMA. 2002;287:831.

	Since this article does not have an abstract, we have provided the first 150 words of the full text and any section headings.

Astronauts aboard the US space shuttle reach dizzying heights—literally. About two thirds of them return to earth with orthostatic intolerance.

Researchers at the University of Texas (UT) Southwestern Medical Center in Dallas who have studied the astronauts said they have pinpointed the mechanism that causes orthostatic intolerance, a condition with symptoms that can include lightheadedness, palpitations, tremulousness, and brief loss of consciousness.

They believe their findings have relevance for improving treatment of the approximately 500 000 Earthbound people in the United States who have the same disorder. The researchers reported their findings last month in an article entitled "Human muscle sympathetic neural and hemodynamic responses to tilt following space flight" (J Physiol. 2002;538.1:331-340).

"HARD-HEARTED" DATA

After analyzing data from six astronauts who flew aboard the 1998 Neurolab space shuttle mission (STS-90), the researchers concluded that orthostatic intolerance is a result of the heart shrinking and becoming stiff . . . [Full Text of this Article]