Sodium in biology mEq/liter (135 - 145 mmol/L). A serum sodium level of less than 135 mEq/L qualifies as hyponatremia, which is considered severe when the serum sodium level is below 125 mEq/L. The renin–angiotensin system and the atrial natriuretic peptide indirectly regulate the amount of signal transduction in the human central nervous system, which depends on sodium ion motion across the nerve cell membrane, in all nerves. Sodium is thus important in neuron function and osmoregulation between cells and the extracellular fluid; the distribution of sodium ions are mediated in all animals by sodium–potassium pumps, which are active transporter solute pumps, pumping
Department of Defense Serum Repository Department of Defense Serum Repository The Department of Defense Serum Repository (also referred to as the DoD Serum Repository or simply DoDSR) is a biological repository operated by the United States Department of Defense containing over 50,000,000 human serum specimens, collected primarily from applicants to and members of the United States Uniformed Services. The DoDSR is located in Silver Spring, Maryland and is operated by the Armed Forces Health Surveillance Center (AFHSC), a subordinate of the United States Army Center for Health Promotion and Preventive Medicine (USACHPPM), itself evolved from the Johns Hopkins School of Hygiene and Public Health. The