Intraluminal Flow Preferentially Increases Net Sodium Uptake in the Rabbit Facial Vein

Abstract

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 µM) and to angiotensin II (0.1 µM). ²²Na⁺ net uptake per unit force developed in response to flow was 7.9-fold greater than that for histamine (1 µM) and twice that for angiotensin II (0.1 µM). 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 µM) and methyl isobutyl amiloride (30 µM) without changes in ⁴⁵Ca²⁺ or ²²Na⁺ net uptake per unit force. Ouabain (10 µM) enhanced flow-induced contraction and the related ²²Na⁺ net uptake. Both ouabain (10 µM) and Bay K 8644 (1 µM) 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 µM). 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.

Increased calcium 45 fluxes in histologically abnormal human ascending aorta

“…3 Tissues were transferred to ice-cold Ca 2ϩ -free physiologic saline solution for 30 minutes to remove extracellular 45 Ca 2ϩ . 4 They were then incubated overnight in ethylenediaminetetraacetic acid (2 mmol/L) at room temperature. Tissue and effluent were analyzed for 45 Ca 2ϩ in a liquid scintillation counter.…”

“…45 Ca 2ϩ efflux was expressed as percent total efflux, and efflux rate constant (per minute) was calculated from the total counts lost from the tissue during each washout period divided by the total counts remaining in the tissue segment. 4 Results were expressed as means Ϯ standard error. The significance of the differences between means was determined by the Student's t test (A. Tedgui).…”