STS-90 Neurolab Program - STS-90 Status Report Flight Day 13 (April 29 CDT) -

Flight Day 13 (April 29 CDT)

Dr. Mano (right) and
Dr. Eckberg watching
the experiment

The STS-90 crewmembers were awakened at 4:29 a.m. (CDT), and began Flight Day 13 activities.

Experiments of the Autonomic Nervous System Team consist of three phases (early, middle and late time flames) during the mission. The response of autonomic nervous experiments were performed in the late phase experiments yesterday and today.
As the part of the experiments like yesterday, an innovative techique called microneurography was repeated.
As they did yesterday, the scientist-astronauts again infused radioactively-labeled norepinephrine into their blood streams and collect blood samples for later analysis.
As part of the Neurolab Mammalian Development Team's research which is studying into gravity's role in stimulating the proper development of the nervous system, seven of the rat neonates were anesthetized and injected two of their hind leg muscles with fluorescent cell marker dyes. One piece of sample's muscle is used on Earth to support the animal's weight, while the other is a non-weight bearing muscle. The label dye will be transported from the muscles, along the nerve cells to the spinal cords of the animals.
This research will help determine whether mammals that develop in microgravity will have normally developed muscles.

The crew will go to sleep at 8:09 p.m. (CDT) this evening and receive a wake up call from Mission Control Center (MCC) tomorrow morning at about 4:09 a.m.

Status of Japan related experiments

The "Autonomic Neuroplasticity in Weightlessness" experiment participating co-investigator Dr. Mano was conducted with the microneurography which is placing a microelectrode in a nerve just below the knee. Is allows nerve signals traveling from the brain to the blood vessels measured directly. This experiment was conducted with the Lower Body Negative Pressure device. LBNP is a hi-tech canister that pulls bodily fluids into the lower extremities, simulating the effect of standing on Earth.

Mission Specialist Hire exchanged data recording magnetic tape of the Vestibular Function Experiment Unit (VFEU) today. The magnetic tapes for recording neural signals are exchanged twice per day.
Hire pulled each Fish Package (FP) of the VFEU out and gave it a movement for the sixth time during flight. This acceleration keeps the oyster toadfish active and allows for better gathering of data.
The neural data has been obtained from the Fish Packages (FPs) of VFEU.

Muscle sympathetic nerve activity was successfully recorded for the first time in space

One of the researches concerning the autonomic nervous system for Neurolab is to analyze human sympathetic nerve activity using microneurography. This research project has been prepared by an international co-operation of 4 Principal Investigators (Prof. G. Blomqvist, Prof. D. L. Eckberg, Prof. D. Robertson from U.S.A. and Dr. F. Baisch from Garmany) and Co-Investigators from U.S.A., Germany and Japan.
Microneurography is a technique to measure electrical signals using a thin electrode with a tip diameter of about 1-micrometer inserted into human nerves. This technique needs much training. Alternative Payload Specialist Dr. Chiaki Mukai Astronaut of Japan has mastered this technique. The aim of micronuerography research in space is to elucidate how the changes in autonomic nervous functions are concerned with the mechanisms underlying cardiovascular deconditioning, particularly blood pressure dysregulation related to spaceflight.
For this aim, microneurography recordings from astronauts were scheduled on the earth before flight, on 12th and 13th days during flight, and after landing. But we have been wondering if microneurography recording is really possible in space, because this technique is very difficult even on the earth and various noise sources are suspected in Space Shuttle.
On April 28, two payload specialists, Dr. J. Pawelczyk and Dr. J. Buckey during flight in Space Shuttle Colombia served as examiner and also as subject. Muscle sympathetic nerve activity, which is important for blood pressure control, was recorded from the peroneal nerve of the right leg to measure the basal level and the responses to various stimuli. The first trial of microneurographic recording of human sympathetic nerve activity in space was very successful without contamination of noise.
It is difficult to mention about the results before the data analysis, but we had an impression that the basal level of muscle sympathetic nerve activity was well preserved under microgravity in space. The sympathetic nerve responses to Valsalva test ( a kind of breath holding), hand gripping, cold pressor test, lower body negative pressure seemed also to be relatively well maintained.
Anyhow the success of miceoneurographic recording of muscle sympathetic nerve activity from astronauts in space is epoch making. The findings obtained from this research may be useful to understand the mechanisms and to establish effective countermeasures of cardiovascular deconditioning related to spaceflight.

Last Updated : April 30, 1998