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First published online January 25, 2005
Journal of Experimental Biology 208, 479-486 (2005)
Published by The Company of Biologists 2005
doi: 10.1242/jeb.01409

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Sodium and anion transport across the avian uterine (shell gland) epithelium

Alisen E. Vetter¹ and Scott M. O'Grady^2,*

¹ Cardiac Rhythm Management, Medtronic Corporation, 7000 Central Avenue NE, Minneapolis, MN 55432, USA
² Departments of Physiology and Animal Science, University of Minnesota, 495 Animal Science/Veterinary Medicine Building, 1988 Fitch Avenue, St Paul, MN 55108, USA

View larger version (63K): [in a new window]   Fig. 1. Histology of the shell gland mucosa. (A) 100x magnification, (B) 400x magnification. PE, pseudostratified surface epithelium; GE, glandular epithelium; SC, stromal cells; CSM, circular smooth muscle; LSM, longitudinal smooth muscle.

View larger version (17K): [in a new window]   Fig. 2. Effects of apical Na+ channel blockers on basal Isc. (A) Time course of Isc inhibition following sequential treatment with 10 and 100 µmol l-1 amiloride. (B) Concentration–response relationships for amiloride and benzamil on basal Isc. The data was fitted using a four-parameter logistic function and the IC50 values were 120 nmol l-1 (N=5) and 810 nmol l-1 (N=5) for benzamil and amiloride, respectively. (C) Magnitudes of amiloride-sensitive (10 µmol l-1) Isc in tissues from hens where shell formation was complete (N=6) compared to tissues where the egg had not entered the shell gland (N=5). *Significantly different from control value (P<0.05).

View larger version (21K): [in a new window]   Fig. 3. Transepithelial Na+ and Cl- flux measurements before and after apical treatment with 10 µmol l-1 amiloride. (A) Unidirectional, apical-to-basolateral (apical-blm), basolateral-to-apical (blm-apical) and net ((apical-blm)-(blm-apical)) Na+ fluxes across epithelial tissues bathed in symmetric avian saline solution and voltage clamped at 0 mV (N=6). (B) Unidirectional and net Cl- fluxes across under the same conditions stated in A (N=5). (C) Effects of apical amiloride (10 µmol l-1) on Isc and conductance (G) measurements obtained from tissues used in the transepithelial flux experiments. *Significantly different from control value (P<0.05).

View larger version (15K): [in a new window]   Fig. 4. Effects of symmetric anion substitution and apical addition of DPC on basal Isc. (A) Isc trace showing the inhibitory effects of 10 µmol l-1 and 100 µmol l-1 DPC on basal anion current in a tissue pretreated with 100 µmol l-1 amiloride. (B) Magnitude of basal Isc inhibition produced by apical DPC, 100 µmol l-1 (N=5), Cl- replacement with methane sulfonate (N=7), HCO3- replacement with Hepes (N=6) and 0.5 mmol l-1 DIDS added to the apical solution (N=5).

View larger version (14K): [in a new window]   Fig. 5. Effects of 8-cpt cAMP (added to both sides) on Isc. (A) Tracing showing the sustained increase in Isc observed after stimulation with 10 µmol l-1 8-cpt cAMP. (B) Effects of 10 µmol l-1 8-cpt cAMP on Isc under Cl- free conditions. Note the inhibitory effects of 10 µmol l-1 acetazolamide (an inhibitor of carbonic anhydrase activity) on the residual current. (C) Effects of Cl- (N=5) and HCO3- (N=5) substitution on the 8-cpt cAMP stimulated Isc response.

View larger version (17K): [in a new window]   Fig. 6. Effects of age and molting on basal amiloride-sensitive and anion-dependent Isc. Note that all experiments were performed in standard avian saline solution. (A) Changes in the amiloride-sensitive Isc with age and molting. (B) Changes in the Cl- and HCO3- dependent Isc with age and molting. *Significantly different from control value (P<0.05).