Intraluminal flow preferentially increases net sodium uptake in the rabbit facial vein

The infusion of physiological salt solution into the lumen of ring segments of the isolated rabbit facial vein induces an increase in vessel wall tone. Changes in 22Na+ and 45Ca2+ net uptake as well as 22Na+ unidirectional efflux in response to flow in this vessel were compared to the response to histamine (1 microM) and to angiotensin II (0.1 microM). 22Na+ net uptake per unit force developed in response to flow was 7.9-fold greater than that for histamine (1 microM) and twice that for angiotensin II (0.1 microM). In comparison, 45Ca2+ net uptake per unit force in response to flow, histamine and K+ were similar. Flow-induced contraction and the related 45Ca2+ and 22Na+ net uptake were decreased by amiloride (30 microM) and methyl isobutyl amiloride (30 microM) without changes in 45Ca2+ or 22Na+ net uptake per unit force. Ouabain (10 microM) enhanced flow-induced contraction and the related 22Na+ net uptake. Both ouabain (10 microM) and Bay K 8644 (1 microM) increased flow-induced contraction and the related 45Ca2+ net uptake whereas they decreased the 45Ca2+ net uptake per unit force. Flow, histamine and angiotensin II increased the unidirectional efflux of 22Na+. This increase in 22Na+ unidirectional efflux was attenuated by ouabain (10 microM). These experiments demonstrate that the increases in wall force due to flow, histamine and angiotensin II are associated with increases in 22Na+ net uptake and unidirectional efflux. Flow preferentially promotes the entry of Na+, compared to histamine and angiotensin II.