SYDNEY M. FRIEDMAN, M.D., Ph.D.
Steep transmembrane concentration gradients in vascular smooth muscle for all ions are maintained by energy-requiring pumps. The Na+ gradient appears to dominate the distribution of the other ions primarily because it controls cell hydration and energizes the transport of sugars, amino acids, and Ca++, Mg++, and H+. The Na+ gradient is a closely regulated constant (about ten to one) and is not perturbed except by changes in the limited permeability of the vascular smooth muscle membrane to Na+ or in the activity of its transport enzyme, the Na+-K+ATPase. Increased permeability to Na+ has been seen in vascular smooth muscle and in erythrocytes in salt-dependent forms of experimental hypertension, as well as in essential hypertension. A compensatory increase in Na+ transport (extrusion) has been seen. This increase in transport can be produced by a moderate increase in aldosterone acting alone or by a lesser increase acting synergistically with vasopressin.
FRIEDMAN SM. Monovalent and Divalent Ions in Vascular Tissue. Ann Intern Med. ;98:753–758. doi: 10.7326/0003-4819-98-5-753
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Published: Ann Intern Med. 1983;98(5_Part_2):753-758.
Cardiology, Coronary Risk Factors, Hypertension, Nephrology.
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Print ISSN: 0003-4819 | Online ISSN: 1539-3704
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