AJP - Renal Physiology, Vol 260, Issue 4 471-F478, Copyright © 1991 by American Physiological Society
Effects of AVP and deoxycorticosterone on Na+ and water transport in the Dahl salt-sensitive rat CCD
C. T. Hawk and J. A. Schafer
Department of Physiology, University of Alabama 35294.
Cortical collecting ducts (CCD) from inbred Dahl salt-sensitive rats were
perfused in vitro to study effects of arginine vasopressin (AVP, present in
the bath) and deoxycorticosterone pivalate (DOC) pretreatment on
lumen-to-bath and bath-to-lumen fluxes of 22Na+ (J1----b and Jb----1 in
pmol.min-1.mm-1, respectively), hydraulic conductivity (Pf, microns/s), and
transepithelial voltage (VT, mV). J1----b was 37.1 +/- 5.3 (mean +/- SE) in
untreated rats and increased to 83.2 +/- 15.9 with AVP. VT increased from
-0.3 +/- 0.6 to -7.0 +/- 2.0. In DOC-pretreated rat CCDs, baseline J1----b
was higher (85.1 +/- 7.6) as was VT (-11.3 +/- 1.7); J1b----b and VT were
doubled with AVP addition (185.6 +/- 18.6 and -21.7 +/- 2.3, respectively).
Thus J1----b in AVP-stimulated CCDs from untreated rats was not
significantly different from control (no AVP) J1----b from DOC-pretreated
rats; however, AVP produced a greater J1----b increase in the latter CCDs.
Neither AVP nor DOC had an effect on Jb----1, which ranged from 25 to 50.
Benzamil reduced J1----b to values not significantly different from
Jb----1, and VT became zero in CCDs treated with both AVP and DOC,
indicating Na+ transport stimulated by both hormones occurs through apical
membrane Na+ channels. Pf increased from 59 +/- 80 to 1,072 +/- 176 with
AVP addition to untreated rat CCDs and was unaltered by DOC or benzamil.
Thus the Dahl rat CCD exhibits a transport response to AVP and DOC that is
indistinguishable from that observed in Sprague-Dawley rats, as previously
reported by this laboratory.
