4. PROGRAMS, MISSIONS, AND PAYLOADS

Cosmos 1667

MISSION PROFILE: Cosmos 1667

Mission Duration: 7 days

Date: July 10-17, 1985

Life Sciences Research Objectives
To study blood pressure and flow responses in primates exposed to microgravity
To correlate other simultaneously recorded physiological information with cardiovascular results

Life Sciences Investigations
Cardiovascular/Cardiopulmonary ( C1667-1)

Organisms Studied
Macaca mulatta (rhesus monkey)

Flight Hardware
Cardiovascular Experiment Hardware - Mod. 1
Cardiovascular Experiment Hardware: Combined Pressure/Flow (CPF) Cuff

The second Cosmos biosatellite mission with a primate payload was launched on July 10, 1985. The biosatellite was recovered on July 17 after the 7-day mission was completed. Mission parameters were very similar to those of Cosmos 1514. Countries participating in the mission included the U.S.S.R., the U.S., France, Czechoslovakia, the German Democratic Republic, Poland, Romania, Bulgaria, and Hungary. The U.S. conducted a single cardiovascular experiment on one of the two flight monkeys. Rats and other organisms were also flown, but no U.S. experiments were conducted on those specimens.

     Although the U.S. experiment on the Cosmos 1667 mission was meant to be a repeat of the Cosmos 1514 cardiovascular experiment, several improvements were implemented on this mission. Modified post-surgery animal handling procedures minimized the risk of damaging the transducer implants. Data was sampled and recorded more frequently during the in-flight period. Two monkeys with flight-type cardiovascular instrumentation were studied in a ground-based synchronous control experiment; postflight cardiovascular tests were not conducted after Cosmos 1514. Postural tilt tests were conducted during the preflight and postflight periods in several animals to establish a ground-based pool of normal data for this procedure. This data was compared with the similar body fluid shifts thought to occur in flight. Instrument calibration procedures were modified on this mission to ensure that blood pressure measurements would be accurate.

U.S. Life Sciences Research Objectives

The main objective of U.S. participation in the Cosmos 1667 mission was to measure carotid artery pressure and blood flow during the in-flight period. The U.S. provided all flight and ground support instrumentation for this experiment. Raw analog data from flight and ground control experiments were transferred to the Cardiovascular Research Laboratory at ARC for analysis. Hemodynamic data were to be correlated with concurrently recorded Soviet data. A similar correlative study was performed during the Cosmos 1514 mission, where blood flow velocity was compared to cardiac output as determined by impedance cardiography. Another goal of the primate cardiovascular experiment on Cosmos 1667 was to use the data obtained to estimate oxygen delivery capacity to the brain during space flight. This procedure was postponed to a future mission because the external carotid artery needed to be ligated to measure brain blood flow.

U.S. Life Sciences Payload

     Organisms

     Two rhesus monkeys (Macaca mulatta) named Gordyy and Oomka were flown onboard the biosatellite. Each animal weighed approximately 4 kg. Both were instrumented for Soviet neurophysiology studies. The instruments consisted of bilaterally implanted microelectrodes in the vestibular nuclei, and electrooculogram and electroencephalogram electrodes. The U.S. cardiovascular experiment was conducted on Gordyy, who was implanted with a device to measure blood pressure and flow in the left common carotid artery.

     Hardware

     As in the Cosmos 1514 mission, monkeys were housed in Soviet BIOS capsules. U.S. hardware developed for the Cosmos 1514 cardiovascular experiment was used again on this mission. A barometric pressure recorder mounted in the primate capsule was used to correct and normalize the implanted pressure sensor to 760 mm of mercury.

*Amount actually consumed may be less. **A total of 400 grams of juice/day/monkey also available if all psychomotor tasks completed. Table 4-9: Cosmos 1667 flight and control monkey experiments.

Operations

Two monkeys with cardiovascular instrumentation, Kvak and Samurai, were used in a synchronous control experiment. A vivarium control experiment was also carried out to determine the animals' responses in a non-stressed environment. Orthostatic (tilt) tests were performed on Gordyy, Kvak, Samurai, and three other animals with cardiovascular instrumentation. These tests were designed to simulate the fluid shifts that occur in animals exposed to microgravity.

     Flight candidate monkeys were trained to operate flight food and juice delivery systems and to tolerate simulated launch and re-entry g loads, flight couch confinement, isolation, and other environmental factors. Other training consisted of behavioral tasks related to Soviet vestibular studies.

     Cardiovascular instrumentation was implanted in one flight animal and in two control animals about two months prior to the flight. Tilt tests were performed on these animals during the preflight period. Preflight data were also gathered on transducer cross calibration, control monitoring, and bioengineering tests.

     During the flight, 5-minute sampling periods every 2 hours in the 16-hour "lights on" period provided carotid flow, carotid pressure, ECG, time code, and ambient pressure data (Fig. 4-44). Data were sampled for 5 minutes every 30 minutes during the "lights off" period.

Figure 4-44: Daily in-flight data sampling on Cosmos 1667. Each sampling period.

     Tilt tests were performed on the flight animal with cardiovascular instrumentation (Gordyy) and one instrumented control animal (Samurai) three days after flight. Both of these animals and one other control animal (Kvak) participated in a ground-based synchronous control experiment one month after the termination of the flight experiment. Tilt tests were again performed, this time on Gordyy, Samurai, Kvak, and three others, after the synchronous control experiment was completed. After all necessary tests had been performed, the data were transferred from Soviet tape recorders to U.S. tape recorders.

Results

The experiment performed on this mission served to strengthen the data obtained from the experiment conducted aboard Cosmos 1514. The most apparent cardiovascular changes were a rapid initial decrease in heart rate followed by further decreases upon continued exposure to the microgravity environment. The changes appeared to be adaptive, and may have served to maintain an adequate supply of blood to the brain during space flight.

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Additional Reading

Hines, J.W. and M.G. Skidmore. U.S. Primate Cardiovascular Experiment Flown on the Soviet Biosatellite Cosmos 1667. Final Report. NASA TM-108803, May 1994.