Summary of final report: Space Life Sciences Planning Workshop (SLSPW). June 5-7, 2000 Mont Tremblant, Quebec.

A Space Life Sciences Planning Workshop was sponsored by the Canadian Space Agency to identify key questions in the major research areas supported by the Life Sciences Program, to identify Canadian strengths and capabilities as they relate to these research areas, and to make recommendations for the future directions of the Life Sciences Program. The conclusions reached by the workshop participants have been presented to the Canadian Space Agency. This report is a summary of those conclusions.

Somatosensory evoked potentials during hypoxia and hypocapnia in conscious humans.

Purpose: The objective of the study was to evaluate the effects of moderate hypoxia and hypocapnia on the latency and amplitude of cortical somatosensory evoked potentials (SSEPs) in conscious human subjects.

Methods: In ten volunteers the amplitude and latency of the cortical somatosensory evoked potentials were recorded during stimulation of the left posterior tibial nerve. Measurements of SSEPs and respiratory variables were made breathing ambient air, air containing a reduced oxygen percentage (17% O2, 14% O2 (n = 6) or 11% O2 (n = 10)), and again during voluntary hyperventilation breathing ambient air (PETCO2 = 20 mmHg, n = 10).

Diurnal changes in lumbar intervertebral distance, measured using ultrasound.

Study Design: This study measured the distances between the tips of the transverse processes of adjacent lumbar vertebrae (L1-L4) in the same subjects after 1 day of normal activities and again the next morning.

Objectives: To determine the feasibility of directly measuring the lumbar intervertebral distance using ultrasound and to determine the magnitude of the diurnal change in the intervertebral distance.

Summary Of Background Data: A diurnal variation in height results from, in part, a decrease in height of the intervertebral discs with loading of the spine during the day.

Long term stability of somatosensory evoked potentials and the effects of microgravity.

Background: Exposure to microgravity causes a height increase of up to 70 mm that places traction on the spine and may possibly lead to spinal cord dysfunction. Somatosensory evoked potentials (SSEP) have been widely used to monitor spinal cord function. This study was carried out to determine the long-term stability of the latency of SSEP's in individual subjects and the feasibility of recording SSEP's in a microgravity environment.

Mechanisms of release of atrial natriuretic factor in vivo.

The aim of the study was to define the relationship between the concentration of immunoreactive atrial natriuretic factor (ANF) in the plasma and atrial stretch, atrial pressure and atrial wall stress during changes in blood volume within the physiological range. Advantage was taken of the potentiation of the release of ANF, in response to blood volume expansion, in the anaesthetized rabbit, by section of the carotid sinus, aortic depressor and vagus nerves. Mean arterial pressure and right and left atrial pressures were measured.