Francisca May

High sodium chloride intake exacerbates immobilization-induced bone resorption and protein losses

We examined, in immobilization, the effect of a diet high in sodium chloride (NaCl) on bone markers, nitrogen balance, and acid-base status. Eight healthy male test subjects participated in a 14-day head-down-tilt bed rest (HDBR) study. During the bed rest period they received, in a randomized crossover design, a high (7.7 meq Na(+)/kg body wt per day) and a low (0.7 meq Na(+)/kg body wt per day) NaCl diet. As expected, 24-h excretion of urinary calcium was significantly greater in the high-NaCl-intake HDBR phase than in the low-NaCl-intake HDBR phase (P < 0.001). High NaCl intake caused a 43-50% greater excretion of the bone resorption markers COOH- (CTX) and NH(2)- (NTX) terminal telopeptide of type I collagen in HDBR than low NaCl in HDBR (CTX/NTX: P < 0.001). Serum concentrations of the bone formation markers bone-specific alkaline phosphatase (bAP) and NH(2)-terminal propeptide of type I procollagen (PINP) were identical in both NaCl intake phases. High NaCl intake led to a more negative nitrogen balance in HDBR (P < 0.001). Changes were accompanied by increased serum chloride concentration (P = 0.008), reduced blood bicarbonate (P = 0.017), and base excess (P = 0.009) whereas net acid excretion was lower during high than during low NaCl intake in immobilization (P < 0.001). High NaCl intake during immobilization exacerbates disuse-induced bone and muscle loss by causing further protein wasting and an increase in bone resorption. Changes in the acid-base status, mainly caused by disturbances in electrolyte metabolism, seem to determine NaCl-induced degradation processes.

Sa1436 The Effect of Simulated Short-Term Microgravitiy on Gastrointestinal Motility, Microflora and Visceral Perception

ents of the HPZ. From prior anatomic studies using simultaneous high resolution manometry and high frequency ultrasound with pharmacologic manipulation, these HPZ components represent a proximal lower esophageal circular muscle sphincter (LEC), a mid crural diaphragm (CD) and a distal gastric sling and clasp muscle fiber complex. The average pressure in each of these components was 24.7+/10.7mmHg in the LEC, 33.2+/-17.2mmHg in the crural diaphragm and 15.83+/-8.03 in the clasp sling muscle fiber complex. The width of the LEC, crural diaphragm and gastric sling clasp fiber complex was 1.01 +/0.25cm, 1.29 +/0.37cm and 0.76 +/0.3 cm respectively. The total length of the high-pressure zone was 4.08 +/0.61 cm. The distance between the peak pressure within the gastric sling and clasp muscle fiber complex and the crural diaphragm was 1.7 +/0.53cm and the distance between the crural diaphragm and the LEC was 1.4 +/-0.48. CONCLUSIONUsing high spatial resolution manometry within the high-pressure zone of the gastroesophageal junction, it is possible to resolve the high-pressure zone into 3 distinct and separate components. These components represent the gastric sling and clasp fiber muscle complex in the proximal stomach, the crural diaphragm measured in the distal esophagus and the LEC muscle proximal to the CD. The average pressure, width and distance between these components were measured.