Whey protein plus bicarbonate supplement has little effects on structural atrophy and proteolysis marker immunopatterns in skeletal muscle disuse during 21 days of bed rest.

OBJECTIVES: To investigate the effect of whey protein plus potassium bicarbonate supplement on disused skeletal muscle structure and proteolysis after bed rest (BR). METHODS: Soleus (SOL) and vastus lateralis (VL) biopsies were sampled from ten (n=10) healthy male subjects (aged 31±6 years) who did BR once with and once without protein supplement as a dietary countermeasure (cross-over study design). The structural changes (myofibre size and type distribution) were analysed by histological sections, and muscle protein breakdown indirectly via the proteolysis markers, calpain 1 and 3, calpastatin, MuRF1 and 2, both in muscle homogenates and by immunohistochemistry. RESULTS: BR caused size-changes in myofiber cross-sectional area (FCSA, SOL, p=0,004; VL, p=0.03), and myofiber slow-to-fast type transition with increased hybrids (SOL, p=0.043; VL, p=0.037) however with campaign differences in SOL (p<0.033). No significant effect of BR and supplement was found by any of the key proteolysis markers. CONCLUSIONS: Campaign differences in structural muscle adaptation may be an issue in cross-over design BR studies. The whey protein plus potassium bicarbonate supplement did not attenuate atrophy and fibre type transition during medium term bed rest. Alkaline whey protein supplements may however be beneficial as adjuncts to exercise countermeasures in disuse.

The perivascular contractile sheath of human placental stem villi: its isolation and characterization.

Former studies have shown that fetal blood vessels of stem villi in the human placenta are enclosed by sheaths of presumed contractile cells. Efforts to prove the contractility of these sheaths by isometric and biochemical investigations still suffer from the difficulty of differentiating between extravascular and vascular (media) contractile cells. The present study describes a method for the selective dissection of perivascular tissue sheaths in stem villi of approximately 2-4 mm thickness, which contained abundant alpha-actin immunoreactive cells and were free of adherent vascular smooth muscle cells. These extravascular contractile cells are part of the 'fibrous paravascular sheath', which, in placental pathology, is used as an index of maturity. To emphasize the high number of contractile cells and their location within this sheath, we propose the common term perivascular contractile sheath (PVCS). The isolation method offers the possibility of selectively investigating the contractile forces of the PVCS and of obtaining more insight into its functional role.