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EFFECTS OF ARTERIAL BLOOD PRESSURE LOADING ON THE BUFFERING CAPACITY OF THE CAROTID-CARDIAC BAROREFLEX RESPONSE. C. B. Nguyen¹, V. A. Convertino², D.F. Doerr³, D.A. Ratliff⁴.   ¹University of California, Davis, ²United States Army Institute of Surgical Research, Fort Sam Houston, TX, ³NASA Biomedical Office, Kennedy Space Center, FL, and ⁴Bionetics Corporation, Kennedy Space Center, FL.

     Long-term exposure to microgravity has been shown to desensitize the carotid-cardiac baroreceptor response.  Reduced baroreceptor sensitivity often leads to hypotension among astronauts.  We tested a straining maneuver (SM) designed to load baroreceptors with blood in the search for an effective countermeasure for preventing orthostatic intolerance.  We measured the buffering capacity of the baroreflex response as represented by the operational point.  Results showed no significant change in buffering capacity when the SM training was used.

     (Supported by NASA and the Spaceflight and Life Sciences Training Program (SLSTP))