TABLE 3.
Serum markers for bone cellular activities in Dry Immersion (DI) and Dry Immersion with Thigh Cuffs (DI-TC) during the 5-day dry immersion and after 48 h- recovery.
| BDC | DI24h | DI48h | DI120h | R+48h | ||
|---|---|---|---|---|---|---|
| Markers for bone turnover | ||||||
| Resorption activity | ||||||
| TRAP5b (U/L) | DI | 2.79(0.80–4.33) | 3.12(0,93–4.88)a | 3.50(0.96–4.98)a,b’ | 3.11(1.08–5.12)a | 3.44(1.05–4.94)a |
| DI-TC | 2.72(1.47–4.60) | 2.93(1.80–6.60) | 3.02(1.92–5.90)a | 3.05(1.90–5.89)a | 3.01(1.80–5.75) | |
| CTx (pmol/L) | DI | 6229(1655–9831) | 6259(1390–11012) | 5977(1619–10180) | 5811(1840–11746) | 5977(2005–10546) |
| DI-TC | 5638(2237–9460) | 5966(2030–9436) | 5830(1958–9780) | 5480(1954–9505) | 6613(2734–10839) | |
| Formation activity | ||||||
| P1NP (µg/L) | DI | 67.2(37.7–109.6) | 61.3(30.6–100.3)a | 59.8(35.0–103.1)a | 55.7(29.7–102.7)a | 58.6(32.8–94.9)a,b |
| DI-TC | 92.5(52.3–136.1) | 84.1(45.5–114.7)a | 81.1(42.2–110.6)a | 68.9(41.4–110.6)a | 76.3(38.7–107.7)a | |
| bAP (µg/L) | DI | 16.0(10.8–20.7) | 17.1(11.2–21.8)a | 17.6(12.8–25.7)a,b’ | 16.5(10.4–22.1)a,c | 14.8(10.4–22.1)b,c,d |
| DI-TC | 21.4(9.0–27.3) | 23.1(9.8–27.4)a’ | 23.4(10.8–28.0)a | 22.4(9.9–27.7)b’,c | 20.2(8.6–25.3)b,c,d | |
| Intact OC (ng/ml) | DI | 23.7(17.9–39.3) | 24.7(15.8–44.1) | 24.2(17.6–44.7) | 21.0(11.6–39.7)a,b,c | 21.2(14.8–39.3)b,c |
| DI-TC | 27.3(13.6–39.5) | 26.6(12.3–39.9) | 29.3(12.4–35.4) | 23.3(9.9–30.4)a,b,c | 24.2(10.4–31.7)a,b’,c | |
| Gla-OC (ng/ml) | DI | 11.9(9.4–16.8) | 13.3(9.4–18.0) | 12.8(8.5–20.0) | 11.8(6.5–18.8)b,c | 11.2(7.9–17.4)a,b,c |
| DI-TC | 12.0(7.3–15.8) | 11.8(7.6–14.6) | 11.9(7.8–16.2)b | 10.4(5.8–15.5)c | 11.3(6.6–15.5)c | |
| Glu-OC (ng/ml) | DI | 7.5(2.9–17.5) | 7.6(3.7–15.5) | 8.2(3.4–17.5) | 5.7(2.9–16.7)c | 5.3(3.6–12.8)b,c |
| DI-TC | 7.6(4.3–16.3) | 8.5(4.4–15.0) | 9.3 (5.2–17.2)b | 7.3(3.4–11.8)b’,c | 6.9(3.5–13.1)c | |
| Osteocyte activity | ||||||
| Periostin (pmol/L) | DI | 990(615–1137) | 934(577–1074) | 708(592–990)a,b | 712(493–977)a,b | 904(710–1138)c,d |
| DI-TC | 740(518–1147) | 835(631–1122) | 729(508–1163) | 742(505–1061) | 713(589–1174) | |
Measurements were made at baseline (BDC), during dry immersion (DI) and after recovery. Data are expressed as median (interquartile range) for n = 9 per group. a,b,c,d: significantly different (p < 0.05) vs. BDC, DI24h, DI48h, DI120h, respectively. a’,b’: trend to significance (p ≤ 0.07) vs. BDC, DI24h, respectively. There is no difference between DI and DI-TC groups. TRAP5b: tartrate-resistant acid phosphatase isoform 5b; CTx: C-terminal crosslinked telopeptide of type I collagen; P1NP: procollagen type I N-terminal propeptide; bAP: bone alkaline phosphatase; OC: osteocalcin; Gla-OCand Glu-OC: carboxylated and uncarboxylated osteocalcin, respectively.