Effect of short-term microgravity and long-term hindlimb unloading on rat cardiac mass and function.
The purpose of this study was to test the hypothesis that exposure to short-term microgravity or long-term hindlimb unloading induces cardiac atrophy in male Sprague-Dawley rats. For the microgravity study, rats were subdivided into four groups: preflight (PF, n = 12); flight (Fl, n = 7); flight cage simulation (Sim, n = 6), and vivarium control (Viv, n = 7). Animals in the Fl group were exposed to 7 days of microgravity during the Spacelab 3 mission. Animals in the hindlimb-unloading study were subdivided into three groups: control (Con, n = 20), 7-day hindlimb-unloaded (7HU, n = 10), and 28-day hindlimb-unloaded (28HU, n = 19). Heart mass was unchanged in adult animals exposed to 7 days of actual microgravity (PF 1.33 +/- 0.03 g; Fl 1.32 +/- 0.02 g; Sim 1.28 +/- 0.04 g; Viv 1.35 +/- 0.04 g). Similarly, heart mass was unaltered with hindlimb unloading (Con 1.40 +/- 0.04 g; 7HU 1.35 +/- 0.06 g; 28HU 1.42 +/- 0.03 g). Hindlimb unloading also had no effect on the peak rate of rise in left ventricular pressure, an estimate of myocardial contractility (Con 8,055 +/- 385 mmHg/s; 28HU 8,545 +/- 755 mmHg/s). These data suggest that cardiac atrophy does not occur after short-term exposure to microgravity and that neither short- nor long-term simulated microgravity alters cardiac mass or function.
Ray
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Department of Medicine, Pennsylvania State University College of Medicine, Hershey, Pennsylvania 17033, USA. caray@psu.edu
Vasques
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Miller
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Wilkerson
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Delp
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D000818:Animals; D001284:Atrophy; D001794:Blood Pressure; D006321:Heart / Q000502:physiology*; D019417:Hindlimb Suspension / Q000502:physiology*; D008297:Male; D018482:Muscle, Skeletal / Q000473:pathology; D009206:Myocardium / Q000473:pathology*; D009929:Organ Size / Q000502:physiology; D051381:Rats; D017207:Rats, Sprague-Dawley; D013610:Tachycardia / Q000473:pathology / Q000503:physiopathology; D013997:Time Factors