title: Diminished plasma cGMP during weightlessness.
abstract: We performed an experiment within the project "RLF" (Russian long-term flight) on a cosmonaut onboard the space station MIR. For creating an analogue to orthostatic stress, we used lower body negative pressure (LBNP) as stimulus. Decrease in central and peripheral baroreceptor load by LBNP can be used as a cardiovascular countermeasure in cosmonauts or for inducing endocrine responses. Altered steady-state plasma concentration values of volume sensitive hormones have been observed inflight as well as postflight. Within this project we measured plasma ANP and cGMP as second messenger. Changes in plasma cGMP concentration are generally considered to be a good indicator of those in ANP activity. However, in our experiments depression of cGMP during space flight was more impressive than ANP decline. We are not aware of previous measurements of plasma cGMP under these conditions, and believe to be the first to report complete suppression of plasma cGMP during long-term stay in space.
authors.affiliation: Department of Physiology, Karl-Franzens University, Graz, Austria.
authors.forename: A
authors.initials: A
authors.lastname: Roessler
authors.forename: H
authors.initials: H
authors.lastname: Hinghofer-Szalkay
authors.forename: V
authors.initials: V
authors.lastname: Noskov
authors.forename: Z
authors.initials: Z
authors.lastname: Laszlo
authors.forename: V V
authors.initials: VV
authors.lastname: Polyakov
mesh_terms: D009320:Atrial Natriuretic Factor / Q000097:blood / Q000378:metabolism*; D001510:Bed Rest; D006152:Cyclic GMP / Q000097:blood / Q000378:metabolism* / Q000502:physiology; D015232:Dinoprostone / Q000378:metabolism; D018475:Head-Down Tilt; D006801:Humans; D008150:Lower Body Negative Pressure; D008297:Male; D009569:Nitric Oxide / Q000378:metabolism; D015290:Second Messenger Systems; D013026:Space Flight; D014893:Weightlessness
chemical_list: D009569:Nitric Oxide; D009320:Atrial Natriuretic Factor; D006152:Cyclic GMP; D015232:Dinoprostone