Hormonal changes with lower body negative pressure on the 6th day in microgravity in one cosmonaut.

We measured volume regulating and stress hormones (AVP, aldosterone, ANP, c-GMP, angiotensin II, PRA, epinephrine, norepinephrine, ACTH, cortisol) in venous blood twice during a lower body negative pressure (LBNP) maneuver in one cosmonaut (31 years, 75 kg, 180 cm) preflight (supine), inflight (6th d in orbit), and on the 4th d (supine) after a 10-d flight. Antecubital blood was taken at the beginning (3 min: "a") and after ceasing (2 min: "b") 40 min LBNP (-15/-30/-35 mm Hg for 15/15/10 min). At the beginning of LBNP, no big changes of resting hormone levels are to be expected. Comparison of "a" values: Inflight, there was a 4-5-fold increase in vasopressin and epinephrine, a slight increase in aldosterone, ANP, norepinephrine, cortisol and ACTH, and a decrease in PRA levels. Postflight, vasopressin was almost as much increased as inflight, and aldosterone and ANP levels were higher than pre- or inflight. PRA, epinephrine, norepinephrine, and cortisol were moderately increased, whereas ACTH and angiotensin II were diminished. Comparison of "b" to "a" values (2 min after LBNP to 3 min intra-LBNP): Preflight, ANP, PRA, and epinephrine rose more than 100%. The inflight response was higher for aldosterone but lower for all other volume active hormones. Postflight, the increase in PRA was pronounced, whereas little change occurred in other hormones. Cortisol and ACTH fell similarly during LBNP under all conditions. In summary, the data provide evidence that not only the endocrine status but also the neuroendocrine responsiveness to stimulation; i.e., the hormone response during cardiovascular load, are altered by the stay in microgravity and readaptation to normal conditions.

A computer controlled automated dispensor for the eluting, calibrating and dispensing of 99Tcm-pertechnetate.

This paper describes an automated 99Tcm-Dispensor, a computer controlled device for the programmed, automated elution of 99Tcm-sodium pertechnetate, its calibration, metered delivery and dilution. The elution can be programmed up to 7 days in advance. The total radioactivity of the eluate is assayed by a semiconductor counter integrated in the shielding of the pertechnetate reservoir. The volume of eluate actually available for dispensing is measured by capacitance and is monitored continuously. The specific concentration is calculated from total activity and volume, and is corrected for decay prior to each delivery. All activity bearing sections are shielded by lead-antimony covers specified to attenuate the radiation from generators up to 2 Ci 99Mo/99Tcm. The labelling vials are inserted into the dispensing chamber within a shielding vessel manually. The sodium pertechnetate solution is dispensed prior to the optional additional delivery of normal saline. The Tc-Dispensor maintains sterility, guards against accidental radioactive contamination, and is suited to reduce the radiation burden of personnel. All operations are recorded by the computer enabling the print-out of protocols. We found the Tc-Dispensor safe, precise and accurate.