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(Abstract 314), Journal of Heart Disease. 4: 2005;79.

 

A THERAPEUTIC STRATEGY USING SUBCUTANEOUS MAGNESIUM TO REDUCE SPACE FLIGHT ISCHEMIC INJURIES  Rowe, W.J.

 

   The objective, to provide magnesium (Mg.) therapy for space flights (SF), thereby reducing potential ischemic complications. Mg. reservoir depletion in skeletal muscle and bone and malabsorption are responsible for SF-related Mg. deficits, conducive to arrhythmias (AR), shown in humans (H), calcium (Ca.) overload of mitochondria, endothelial injuries (EI) in rodents, and oxidative stress shown in both. Clinorotation of cultured human endothelial cells (simulating microgravity) show decreased proliferative activity and thinning of actin filaments (impaired motility). Invariable dehydration, insulin resistance, space walks (SW)- sinus tachycardia (over 160/ min.), decreased Mg., cyclic GMP, vascular endothelial growth factor (VEGF), platelets, and elevations of catecholamines, angiotensin, aldosterone, cytokines, have all been shown in H. Irwin (Apollo 15) had AR, described classical angina with severe dyspnea during reentry (7 Gs).It's been postulated that there may be SF-intracellular shift of Ca induced by high ambient C02(0.5-0.7%). For total over 2 hours, prior and during SW up to 8 Hr., 100% oxygen is required. Because of SF -malabsorption and potential renal, hepatic dysfunction, and deterioration of some pharmaceuticals (P), their use is limited. Mg., an antioxidant, Ca. blocker, simulates VEGF and induces nitric oxide synthesis. Stable subcutaneous Mg 1-aspartate-hydrochloride is available. A dependable, replenishable delivery device must be developed. Intracellular Mg. levels should be monitored from sublingual cells by X-ray dispersion. A strategy is proposed, monitoring and correcting SF - Mg deficits, partially compensating for problems with P, reducing potential oxidative stress, Ca. overload, AR, EI.