title: Relationship between plasma sodium concentration and vascular reactivity in man.
abstract: Experiments were done to study the effects of acute changes in plasma sodium concentration [Na] on vasoconstrictor responses to norepinephrine and to reflex sympathetic stimulation in man. [Na] in the venous return from the forearm of each of 21 normal subjects was reduced (to an average of 118 mEq/liter), increased (147 mEq/liter), and maintained within the normal range (140 mEq/liter) by means of infusions into the brachial artery of three solutions containing different [Na]. Mannitol or sucrose and disodium sulfate were substituted for sodium chloride to produce the desired changes in [Na] without changing blood osmolarity. Blood flow to the forearm (plethysmograph) increased during infusion of the three solutions, but the increase in flow was not related to [Na]. Vasoconstrictor responses to injections of norepinephrine and angiotensin into the brachial artery were reduced at low [Na] and augmented at high [Na]. Reflex vasoconstriction, activated by lower body negative pressure, was similarly affected by changes in [Na]. In the isolated, perfused gracilis muscle of dog vasoconstrictor responses to norepinephrine and to nerve stimulation were attenuated, and the extraction of norepinephrine by this muscle was smaller when plasma [Na] was reduced.
mesh_terms: D000328:Adult; D000704:Analysis of Variance; D000804:Angiotensin II / Q000494:pharmacology; D000818:Animals; D001274:Atmospheric Pressure; D001916:Brachial Artery; D004285:Dogs; D004558:Electric Stimulation; D004837:Epinephrine / Q000494:pharmacology*; D005542:Forearm / Q000098:blood supply; D006400:Hematocrit; D006801:Humans; D008297:Male; D008353:Mannitol / Q000494:pharmacology; D009132:Muscles / Q000098:blood supply / Q000378:metabolism; D009638:Norepinephrine / Q000378:metabolism; D009994:Osmolar Concentration; D010477:Perfusion; D010992:Plethysmography, Impedance; D011188:Potassium / Q000097:blood; D012964:Sodium / Q000097:blood*; D013395:Sucrose / Q000494:pharmacology; D013431:Sulfates / Q000494:pharmacology; D013564:Sympathetic Nervous System / Q000502:physiology*; D014662:Vasoconstrictor Agents / Q000494:pharmacology*; D014666:Vasomotor System / Q000187:drug effects*
chemical_list: D013431:Sulfates; D014662:Vasoconstrictor Agents; D000804:Angiotensin II; D008353:Mannitol; D013395:Sucrose; D012964:Sodium; D011188:Potassium; D009638:Norepinephrine; D004837:Epinephrine