Calcium metabolism and cardiovascular function after spaceflight

McCarron. Calcium metabolism and cardiovascular func-tion after spaceflight. J Appl Physiol 92: 3–12, 2002.—To determine the influence of dietary calcium on spaceflight-induced alterations in calcium metabolism and blood pres-sure (BP), 9-wk-old spontaneously hypertensive rats, fed either high- (2%) or low-calcium (0.02%) diets, were flown on an 18-day shuttle flight. On landing, flight animals had increased ionized calcium (P, 0.001), elevated parathyroid hormone levels (P, 0.001), reduced calcitonin levels (P, 0.05), unchanged 1,25(OH)2D3 levels, and elevated skull (P, 0.01) and reduced femur bone mineral density. Basal and thrombin-stimulated platelet free calcium (intracellular cal-cium concentration) were also reduced (P, 0.05). There was a tendency for indirect systolic BP to be reduced in conscious flight animals (P 5 0.057). However, mean arterial pressur