摘要:

The adaptation of a slow (soleus, Sol) and a fast (medial gastrocnemius, MG) skeletal muscle to spaceflight was studied in five young male rats. The flight period was 12.5 days and the rats were killed approximately 48 h after returning to 1g.Five other rats that were housed in cages similar to those used by the flight rats were maintained at 1gfor the same period of time to serve as ground‐based controls. Fibers were classified as dark or light staining for myosin adenosine triphosphatase (ATPase). On the average, the fibers in the Sol of the flight rats atrophied twice as much as those in the MG. Further, the fibers located in the deep (close to the bone and having the highest percentage of light ATPase and high oxidative fibers in the muscle cross section) region of the MG atrophied more than the fibers located in the superficial (away from the bone and having the lowest percentage of light ATPase and high oxidative fibers in the muscle cross‐section) region of the muscle. Based on quantitative histochemical assays of single muscle fibers, succinate dehydrogenase (SDH) activity per unit volume was unchanged in fibers of the Sol and MG. However, in the Sol, but not the MG, the total amount of SDH activity in a 10‐μm‐thick section of a fiber decreased significantly in response to spaceflight. Based on population distributions, it appears that the α‐glycerophosphate dehydrogenase (GPD) activities were elevated in the dark ATPase fibers in the Sol, whereas the light fibers in the Sol and both fiber types in the MG did not appear to change. The ratio of GPD to SDH activities increased in the dark (but not light) fibers of the Sol and was unaffected in the MG. Immunohistochemical analyses indicate that approximately 40% of the fibers in the Sol of flight rats expressed a fast myosin heavy chain compared with 22% in control rats. Further, 31% of the fibers in the Sol of flight rats expressed both fast and slow myosin heavy chains compared with 8% in control rats. Immunohistochemical changes in the MG were minimal. These data suggest that the magnitude and direction of enzymatic activity and cell volume changes are dependent on the muscle, the region of the muscle, and the type of myosin expressed in the fibers. Further, the ability of fibers to maintain normal or even elevated activities per unit volume of some metabolic enzymes is remarkable considering the marked and rapid decrease in fiber volume.—Miu, B.; Martin, T. P.; Roy, R. R.; Oganov, V.; Ilyina‐Kakueva, E.; Marini, J. F.; Leger, J. J.; Bodine‐Fowler, S. C.; Edgerton, V. R. Metabolic and morphologic properties of single muscle fibers in the rat after spaceflight, Cosmos 1887.FASEB J.4: 64‐72; 1990.

ISSN:0892-6638    

DOI:10.1096/fasebj.4.1.2136839

出版商:Wiley    

年代:1990

数据来源: WILEY

摘要:

Morphological changes were observed in the left ventricle of rat heart tissue from animals flown on the Cosmos 1887 biosatellite for 12.5 days. These tissues were compared to the synchronous and vivarium control hearts. While many normal myofibrils were observed, others exhibited ultrastructural alterations, i.e., damaged and irregular‐shaped mitochondria and generalized myofibrillar edema. Analysis of variance (ANOVA) of the volume density data revealed a statistically significant increase in glycogen and a significant decrease in mitochondria compared to the synchronous and vivarium controls. Point counting indicated an increase in lipid and myeloid bodies and a decrease in microtubules, but these changes were not statistically significant. In addition, the flight animals exhibited some patchy loss of protofibrils (actin and myosin filaments) and some abnormal supercontracted myofibrils that were not seen in the controls. This study was undertaken to gain insight into the mechanistic aspects of cardiac changes in both animals and human beings as a consequence of space travel (1). Cardiac hypotrophy and fluid shifts have been observed after actual or simulated weightlessness and raise concerns about the functioning of the heart and circulatory system during and after travel in space (2‐4).— Philpott, D. E.; Popova, I. A.; Kato, K.; Stevenson, J.; Miquel, J.; Sapp, W. Morphological and biochemical examination of Cosmos 1887 rat heart tissue: Part I‐ultrastructure.FASEB J.4: 73‐78; 1990.

ISSN:0892-6638    

DOI:10.1096/fasebj.4.1.2295379

出版商:Wiley    

年代:1990

数据来源: WILEY

摘要:

The purpose of this experiment was to investigate the effects of 12.5 days of zero gravity (0g) exposure (Cosmos 1887 Biosputnik) on the enzymatic properties, protein content, and isomyosin distribution of the myofibril fraction of the slow‐twitch vastus intermedius (VI) and the fast‐twitch vastus lateralis (VL) muscles of adult male rats. Measurements were obtained on three experimental groups (n= 5 each group) designated as flight group (FG), vivarium control (VC), and synchronous control (SC). Body weight of the FG was significantly lower than that of the two control groups (P<0.05). Compared with the two control groups, VI weight was lower by 23% (P<0.10), whereas no such pattern was apparent for the VL muscle. Myofibril yields (mg protein/g muscle) in the VI were 35% lower in the FG than in controls (P<0.05), whereas no such pattern was apparent for the VL muscle. When myofibril yields were expressed on a muscle basis (mg/g × muscle weight), the loss of myofibril protein was more exaggerated and suggests that myofibril protein degradation is an early event in the muscle atrophy response to 0g.Analysis of myosin isoforms indicated that slow myosin (Sm) was the primary isoform lost in the calculated degradation of total myosin. No evidence of loss of the fast isomyosins was apparent for either muscle following spaceflight. Myofibril ATPase activity of the VI was increased in the FG compared with controls, which is consistent with the observation of preferential Sm degradation. These data suggest that muscles containing a high percentage of slow‐twitch fibers undergo greater degrees of myofibril protein degradation than muscles containing predominantly fast‐twitch fibers in response to a relatively short period of 0gexposure, and the primary target appears to be the Sm molecule.—Baldwin, K. M., Herrick, R. E., Ilyina‐Kakueva, E.,andOganov, V. S. Effects of zero gravity on myofibril content and isomyosin distribution in rodent skeletal muscle.FASEB J.4: 79‐83; 1990.

ISSN:0892-6638    

DOI:10.1096/fasebj.4.1.2136840

出版商:Wiley    

年代:1990

数据来源: WILEY

摘要:

Histochemical and ultrastructural analyses were performed postflight on hind limb skeletal muscles of rats orbited for 12.5 days aboard the unmanned Cosmos 1887 biosatellite and returned to Earth 2 days before sacrifice. The antigravity adductor longus (AL), soleus, and plantaris muscles atrophied more than the non‐weight‐bearing extensor digitorum longus, and slow muscle fibers were more atrophic than fast fibers. Muscle fiber segmental necrosis occurred selectively in the AL and soleus muscles; primarily, macrophages and neutrophils infiltrated and phagocytosed cellular debris. Granule‐rich mast cells were diminished in flight AL muscles compared with controls, indicating that mast cell secretion contributed to interstitial tissue edema. Increased ubiquitination of disrupted myofibrils implicated ubiquitin in myofilament degradation. Mitochondrial content and succinic dehydrogenase activity were normal, except for subsarcolemmal decreases. Myofibrillar ATPase activity of flight AL muscle fibers shifted toward the fast type. Absence of capillaries and extravasation of red blood cells indicated failed microcirculation. Muscle fiber regeneration from activated satellite cells was detected. About 17% of the flight AL end plates exhibited total or partial denervation. Thus, skeletal muscle weakness associated with spaceflight can result from muscle fiber atrophy and segmental necrosis, partial motor denervation, and disruption of the microcirculation.— Riley, D. A.; Ilyina‐Kakueva, E. I.; Ellis, S.; Bain, J. L. W.; Slocum, G. R.;andSedlak, F. R. Skeletal muscle fiber, nerve, and blood vessel breakdown in space‐flown rats.FASEB J4: 84‐91; 1990.

ISSN:0892-6638    

DOI:10.1096/fasebj.4.1.2153085

出版商:Wiley    

年代:1990

数据来源: WILEY

摘要:

The mitotic indices, villus heights, and crypt depths were determined in each of three jejunal regions (proximal, middle, and distal) for five animals each in the flight, vivarium, and synchronous groups. Because of the rapid turnover of intestinal mucosal cells and the delay in recovering the flight animals, it is not known whether the proliferation of jejunal mucosal cells is affected by microgravity conditions associated with spaceflight. However, since there were no consistent differences between animals in the flight group and those in the synchronous and vivarium control groups, it appears that any effects of microgravity on the turnover of jejunal mucosal cells are short‐lived. Thus, this study represents an initial step in determining the effects of microgravity on the proliferation and turnover of intestinal mucosal cells.—Sawyer, H. R.; Moeller, C. L.; Phillips, R. W.; Smirnov, K. L. Effects of spaceflight on the proliferation of jejunal mucosal cells.FASEB J.4: 92‐94; 1990.

ISSN:0892-6638    

DOI:10.1096/fasebj.4.1.2295380

出版商:Wiley    

年代:1990

数据来源: WILEY

摘要:

To determine the possible biochemical effects of prolonged weightlessness on liver function, samples of liver from rats that had flown aboard Cosmos 1887 were analyzed for protein, glycogen, and lipids as well as the activities of a number of key enzymes involved in metabolism of these compounds and xenobiotics. Among the parameters measured, the major differences were elevations in the glycogen content and hydroxymethylglutaryl‐CoA (HMG‐CoA) reductase activities for the rats flown on Cosmos 1887 and decreases in the amount of microsomal cytochrome P‐450 and the activities of aniline hydroxylase and ethylmorphineN‐demethylase, cytochrome P‐450‐dependent enzymes. These results support the earlier finding of differences in these parameters and suggest that altered hepatic function could be important during spaceflight and/or the postflight recovery period.—Merrill, A. H., Jr.; Hoel, M.; Wang, E.; Mullins, R. E.; Hargrove, J. L.; Jones, D. P.; Popova, I. A. Altered carbohydrate, lipid, and xenobiotic metabolism by liver from rats flown on Cosmos1887. FASEB J.4: 95‐100; 1990.

ISSN:0892-6638    

DOI:10.1096/fasebj.4.1.2295381

出版商:Wiley    

年代:1990

数据来源: WILEY

摘要:

Testes from rats flown on Cosmos 1887 were compared with vivarium control and synchronous control samples. The mean weights of flight testes, normalized for weight per 100 g, were 6.4% less when compared with the vivarium controls. Counts of spermatogonia from tissue sections (seminiferous tubules in maturation stage 6) from five animals in each group revealed 4% fewer spermatogonia in flight testes compared with synchronous controls and 11% fewer spermatogonia in flight samples compared with vivarium controls.— Sapp, W. J.; Philpott, D. E.; Williams, C. S.; Kato, K.; Stevenson, J.; Vasquez, M.;andSerova, L. V. Effects of spaceflight on the spermatogonial population of rat seminiferous epithelium.FASEB J.4: 101‐104; 1990.

ISSN:0892-6638    

DOI:10.1096/fasebj.4.1.2295370

出版商:Wiley    

年代:1990

数据来源: WILEY

摘要:

The Cosmos 1887 biosatellite carried 10 male rats and 2 rhesus monkeys on its 12.5‐day mission. Upon reentry the Vostok vehicle overshot the designated landing site, which resulted in fasting of the animals for 42 h, exposure to cage temperatures of 12‐15°C, and 2 days delay in death of the rats. No overt untoward effects of the delayed recovery were apparent. Tissues from the rats were harvested by Soviet scientists, appropriately preserved, and provided to U.S. investigators. Flight rats grew more slowly and had larger adrenal glands than earth gravity controls. Analysis of plasma revealed increased concentrations of hepatic alkaline phosphatase, glucose, urea nitrogen, and creatinine in flight rats. In contrast, electrolytes, total protein, albumin, corticosterone, prolactin, and immunoreactive growth hormone levels were unchanged. However, testosterone concentration was marginally decreased after flight and thyroid hormone levels were suggestive of reduced thyroid function. Due to the possible effects of reentry and the delay in recovery of the animals, it is not clear what relationship postflight levels of plasma constituents bear to their concentrations in flight.—Grindeland, R. E.; Popova, I. A.; Vasques, M.; Arnaud, S. B. Cosmos 1887 mission overview: effects of microgravity on rat body and adrenal weights and plasma constituents.FASEB J.4: 105‐109; 1990.

ISSN:0892-6638    

DOI:10.1096/fasebj.4.1.2295371

出版商:Wiley    

年代:1990

数据来源: WILEY

ISSN:0892-6638    

DOI:10.1096/fasebj.4.1.2403950

出版商:Wiley    

年代:1990

数据来源: WILEY

ISSN:0892-6638    

DOI:10.1096/fasebj.4.1.2295372

出版商:Wiley    

年代:1990

数据来源: WILEY