Luminal vasopressin modulates transport in the rabbit cortical collecting duct.
We explored the action of luminal AVP in rabbit CCD perfused in vitro at 37 degrees C. Nanomolar concentrations of luminal AVP induced a sustained hyperpolarization of transepithelial voltage (Vt) in contrast to a transient hyperpolarization caused by basolateral AVP. 10 microM basolateral ouabain abolished the latter but not the former change in Vt. Despite a sustained hyperpolarization (from -20.7 +/- 2.9 to -34.1 +/- 4.7 mV; P less than 0.01), 10 nM luminal AVP only slightly altered net Na+ and K+ fluxes (7.6% stimulation and no significant change, respectively). Instead, luminal AVP appeared to modulate an acetazolamide-sensitive electrogenic ion transport because 200 microM basolateral acetazolamide suppressed the luminal AVP-induced hyperpolarization (percentage of Vt from -50.4 +/- 10.8 to -5.1 +/- 1.4; P less than 0.005). In terms of water transport, 10 nM luminal AVP did not change hydraulic conductivity (Lp, x 10(-7) cm/atm per s) (from 3.9 +/- 0.8 to 5.0 +/- 1.2), but suppressed the increase in Lp induced by 20 pM basolateral AVP (134.9 +/- 19.2 vs. 204.3 +/- 21.1 in control; P less than 0.05). These findings demonstrate distinct luminal action of AVP, suggesting amphilateral regulation of epithelial transport by AVP in the CCD.
Ando
Y
Y
Division of Nephrology, Jichi Medical School Hospital, Tochigi, Japan.
Tabei
K
K
Asano
Y
Y
D000042:Absorption; D000086:Acetazolamide / Q000494:pharmacology; D000818:Animals; D001127:Arginine Vasopressin / Q000494:pharmacology* / Q000502:physiology; D001464:Barium / Q000494:pharmacology; D001692:Biological Transport / Q000187:drug effects; D005934:Glucagon / Q000494:pharmacology; D066298:In Vitro Techniques; D007685:Kidney Tubules, Collecting / Q000187:drug effects / Q000378:metabolism*; D008297:Male; D011188:Potassium / Q000378:metabolism; D011817:Rabbits; D012964:Sodium / Q000378:metabolism
D001127:Arginine Vasopressin; D001464:Barium; D005934:Glucagon; D012964:Sodium; D000086:Acetazolamide; D011188:Potassium