Effect of ADH on chloride reabsorption in the loop of Henle of the Brattleboro rat

Publisher Website
Google Scholar
Abstract
Both in vivo superficial loop segment microperfusion and in vitro perfusion of isolated medullary thick ascending limb segments were used to assess the effect of vasopressin on loop of Henle chloride absorption in the Brattleboro rat. Superficial loop segments were perfused between the latest proximal and earliest distal tubule in vivo at 19.2 .+-. 0.4 nl/min (mean .+-. SE) with an artificial tubule fluid. Under control conditions, absolute chloride reabsorption was 1,596 .+-. 61 pmol/min and increased to 1,876 .+-. 102 after intravenous infusion of vasopressin (P < 0.005). Distal tubule fluid chloride concentration decreased (P < 0.005). Distal tubule fluid chloride concentration decreased 4.6 .+-. 1.5 meq/liter (P < 0.05). For in vitro perfusion, medullary thick ascending limb segments were bathed and perfused (9-15 nl/min) with phosphate-buffered solutions at 38.degree. C. Under control conditions, transepithelial voltage was +2.4 .+-. 0.3 mV, lumen positive, and the net chloride flux was 147 .+-. 24 pmol .cntdot. min-1 .cntdot. mm-1 in the absorptive direction. Addition of vasopressin to the bathing solution increased net chloride reabsorption to 342 .+-. 56 pmol .cntdot. min-1 .cntdot. mm-1 (P < 0.02) and transepithelial voltage to 3.0 .+-. 0.3 mV (P < 0.002). An additional group of tubules was examined under identical conditions; however, vasopressin was removed from the bathing medium during a subsequent recovery period. In these experiments, net chloride flux and transepithelial voltage significantly increased compared with the control period and returned to control values upon removal of vasopressin from the bath. These results demonstrate that vasopressin enhances chloride reabsorption in the Brattleboro rat both in vivo in the loop segment and in vitro in the medullary thick ascending limb.

This publication has 1 reference indexed in Scilit: