Cardiovascular results from a rhesus monkey flown aboard the Cosmos 1514 spaceflight

Pressure and flow relationships to the head were measured before and during spaceflight by means of a chronically implanted cuff placed about the left common carotid artery in one of two rhesus monkeys flown aboard Cosmos 1514. Measurements were obtained daily for 4 min every 2 h during the 5-d spaceflight and compared to identical recordings obtained during a 35-h pre-flight control period 9 d before flight and a 12-h period while on the launch pad. Mean arterial pressure demonstrated a 10% increase compared to control levels immediately on insertion into orbit and maintained a 16-27% increase over the first few hours of flight before returning to baseline levels. Blood flow velocity showed a marked increase (approximately 8 cm/s) compared to pre-flight control while on the launch pad which was maintained over the duration of the flight. Blood flow showed reciprocal changes to pressure on orbital insertion. Cardiovascular system changes persisted into the second day of flight and were most clearly indicated by a decrease in relative differences between blood flow to the head and total cardiac output as measured by impedance plethysmography. Signs of adaptation appeared on days 3-5 of flight.