Cyclic adenosine monophosphate-stimulated bicarbonate secretion in rabbit cortical collecting tubules

Research output: Contribution to journalArticle

47 Citations (Scopus)

Abstract

We studied the effects of cyclic AMP (cAMP) on HCO3- transport by rabbit cortical collecting tubules perfused in vitro. Net HCO3- secretion was observed in tubules from NaHCO3- loaded rabbits. 8-Bromo-cAMP-stimulated net HCO3- secretion, whereas secretion fell with time in control tubules. Both isoproterenol and vasopressin (ADH) are known to stimulate adenylate cyclase in this epithelium; however, only isoproterenol stimulated net HCO3- secretion. The mechanism of cAMP-stimulated HCO3- secretion was examined. If both HCO3- and H+ secretion were to occur simultaneously in tubules exhibiting net HCO3- secretion, cAMP might increase the net HCO3- secretory rate by inhibiting H+ secretion, by stimulating HCO3- secretion, or both. These possibilities were examined using basolateral addition of the disulfonic stilbene (4,4'-diisothiocyanostilbene-2,2'-disulfonate (DIDS). In acidifying tubules from NH4Cl-loaded rabbits, DIDS eliminated HCO3- reabsorption, a result consistent with known effects of DIDS as an inhibitor of H+ secretion. In contrast, cAMP left acidification (H+ secretion) intact. DIDS applied to HCO3- secretory tubules failed to increase the HCO3- secretory rate, indicating minimal H+ secretion in HCO3- secreting tubules. Thus, inhibition of H+ secretion by cAMP could not account for the cAMP-induced stimulation of net HCO3- secretion. cAMP-stimulated HCO3- secretion was reversibly eliminated by 0 Cl perfusate, whereas luminal DIDS had no effect. Bath amiloride (1 mM) failed to eliminate cAMP-stimulated HCO3- secretion when bath [Na+] was 145 mM or 5 mM. cAMP depolarized the transepithelial voltage. The collected fluid [HCO3-] after cAMP could be accounted for by electrical driving forces, suggesting that cAMP stimulates passive HCO3- secretion. However, cAMP did not alter HCO3- permeability measured under conditions expected to inhibit transcellular HCO3- movement (0 Cl- solutions and bath DIDS). This measured HCO3- permeability was not high enough to account, by passive diffusion, for the HCO3- fluxes observed in Cl- containing solutions. We conclude the following: 1) cAMP increased net HCO3- secretion by stimulating HCO3- secretion and not by inhibiting H+ secretion; 2) this HCO3- secretion may have occurred by Cl-HCO3- exchange; 3) Na+-H+ exchange appeared not to play a role in basolateral H+ extrusion under these conditions; and 4) the stimulation of HCO3- secretion by isoproterenol, but not ADH, suggests the existence of separate cell cAMP pools or cellular heterogeneity in this cAMP response.

Original languageEnglish (US)
Pages (from-to)2056-2064
Number of pages9
JournalJournal of Clinical Investigation
Volume75
Issue number6
StatePublished - 1985
Externally publishedYes

Fingerprint

Bicarbonates
Cyclic AMP
Rabbits
Baths
Isoproterenol
Secretory Rate
Permeability
8-Bromo Cyclic Adenosine Monophosphate
Stilbenes
Amiloride
Vasopressins
Adenylyl Cyclases
Epithelium

ASJC Scopus subject areas

  • Medicine(all)

Cite this

@article{acf4d492a4874752b5ffe81cecc487ad,
title = "Cyclic adenosine monophosphate-stimulated bicarbonate secretion in rabbit cortical collecting tubules",
abstract = "We studied the effects of cyclic AMP (cAMP) on HCO3- transport by rabbit cortical collecting tubules perfused in vitro. Net HCO3- secretion was observed in tubules from NaHCO3- loaded rabbits. 8-Bromo-cAMP-stimulated net HCO3- secretion, whereas secretion fell with time in control tubules. Both isoproterenol and vasopressin (ADH) are known to stimulate adenylate cyclase in this epithelium; however, only isoproterenol stimulated net HCO3- secretion. The mechanism of cAMP-stimulated HCO3- secretion was examined. If both HCO3- and H+ secretion were to occur simultaneously in tubules exhibiting net HCO3- secretion, cAMP might increase the net HCO3- secretory rate by inhibiting H+ secretion, by stimulating HCO3- secretion, or both. These possibilities were examined using basolateral addition of the disulfonic stilbene (4,4'-diisothiocyanostilbene-2,2'-disulfonate (DIDS). In acidifying tubules from NH4Cl-loaded rabbits, DIDS eliminated HCO3- reabsorption, a result consistent with known effects of DIDS as an inhibitor of H+ secretion. In contrast, cAMP left acidification (H+ secretion) intact. DIDS applied to HCO3- secretory tubules failed to increase the HCO3- secretory rate, indicating minimal H+ secretion in HCO3- secreting tubules. Thus, inhibition of H+ secretion by cAMP could not account for the cAMP-induced stimulation of net HCO3- secretion. cAMP-stimulated HCO3- secretion was reversibly eliminated by 0 Cl perfusate, whereas luminal DIDS had no effect. Bath amiloride (1 mM) failed to eliminate cAMP-stimulated HCO3- secretion when bath [Na+] was 145 mM or 5 mM. cAMP depolarized the transepithelial voltage. The collected fluid [HCO3-] after cAMP could be accounted for by electrical driving forces, suggesting that cAMP stimulates passive HCO3- secretion. However, cAMP did not alter HCO3- permeability measured under conditions expected to inhibit transcellular HCO3- movement (0 Cl- solutions and bath DIDS). This measured HCO3- permeability was not high enough to account, by passive diffusion, for the HCO3- fluxes observed in Cl- containing solutions. We conclude the following: 1) cAMP increased net HCO3- secretion by stimulating HCO3- secretion and not by inhibiting H+ secretion; 2) this HCO3- secretion may have occurred by Cl-HCO3- exchange; 3) Na+-H+ exchange appeared not to play a role in basolateral H+ extrusion under these conditions; and 4) the stimulation of HCO3- secretion by isoproterenol, but not ADH, suggests the existence of separate cell cAMP pools or cellular heterogeneity in this cAMP response.",
author = "Schuster, {Victor L.}",
year = "1985",
language = "English (US)",
volume = "75",
pages = "2056--2064",
journal = "Journal of Clinical Investigation",
issn = "0021-9738",
publisher = "The American Society for Clinical Investigation",
number = "6",

}

TY - JOUR

T1 - Cyclic adenosine monophosphate-stimulated bicarbonate secretion in rabbit cortical collecting tubules

AU - Schuster, Victor L.

PY - 1985

Y1 - 1985

N2 - We studied the effects of cyclic AMP (cAMP) on HCO3- transport by rabbit cortical collecting tubules perfused in vitro. Net HCO3- secretion was observed in tubules from NaHCO3- loaded rabbits. 8-Bromo-cAMP-stimulated net HCO3- secretion, whereas secretion fell with time in control tubules. Both isoproterenol and vasopressin (ADH) are known to stimulate adenylate cyclase in this epithelium; however, only isoproterenol stimulated net HCO3- secretion. The mechanism of cAMP-stimulated HCO3- secretion was examined. If both HCO3- and H+ secretion were to occur simultaneously in tubules exhibiting net HCO3- secretion, cAMP might increase the net HCO3- secretory rate by inhibiting H+ secretion, by stimulating HCO3- secretion, or both. These possibilities were examined using basolateral addition of the disulfonic stilbene (4,4'-diisothiocyanostilbene-2,2'-disulfonate (DIDS). In acidifying tubules from NH4Cl-loaded rabbits, DIDS eliminated HCO3- reabsorption, a result consistent with known effects of DIDS as an inhibitor of H+ secretion. In contrast, cAMP left acidification (H+ secretion) intact. DIDS applied to HCO3- secretory tubules failed to increase the HCO3- secretory rate, indicating minimal H+ secretion in HCO3- secreting tubules. Thus, inhibition of H+ secretion by cAMP could not account for the cAMP-induced stimulation of net HCO3- secretion. cAMP-stimulated HCO3- secretion was reversibly eliminated by 0 Cl perfusate, whereas luminal DIDS had no effect. Bath amiloride (1 mM) failed to eliminate cAMP-stimulated HCO3- secretion when bath [Na+] was 145 mM or 5 mM. cAMP depolarized the transepithelial voltage. The collected fluid [HCO3-] after cAMP could be accounted for by electrical driving forces, suggesting that cAMP stimulates passive HCO3- secretion. However, cAMP did not alter HCO3- permeability measured under conditions expected to inhibit transcellular HCO3- movement (0 Cl- solutions and bath DIDS). This measured HCO3- permeability was not high enough to account, by passive diffusion, for the HCO3- fluxes observed in Cl- containing solutions. We conclude the following: 1) cAMP increased net HCO3- secretion by stimulating HCO3- secretion and not by inhibiting H+ secretion; 2) this HCO3- secretion may have occurred by Cl-HCO3- exchange; 3) Na+-H+ exchange appeared not to play a role in basolateral H+ extrusion under these conditions; and 4) the stimulation of HCO3- secretion by isoproterenol, but not ADH, suggests the existence of separate cell cAMP pools or cellular heterogeneity in this cAMP response.

AB - We studied the effects of cyclic AMP (cAMP) on HCO3- transport by rabbit cortical collecting tubules perfused in vitro. Net HCO3- secretion was observed in tubules from NaHCO3- loaded rabbits. 8-Bromo-cAMP-stimulated net HCO3- secretion, whereas secretion fell with time in control tubules. Both isoproterenol and vasopressin (ADH) are known to stimulate adenylate cyclase in this epithelium; however, only isoproterenol stimulated net HCO3- secretion. The mechanism of cAMP-stimulated HCO3- secretion was examined. If both HCO3- and H+ secretion were to occur simultaneously in tubules exhibiting net HCO3- secretion, cAMP might increase the net HCO3- secretory rate by inhibiting H+ secretion, by stimulating HCO3- secretion, or both. These possibilities were examined using basolateral addition of the disulfonic stilbene (4,4'-diisothiocyanostilbene-2,2'-disulfonate (DIDS). In acidifying tubules from NH4Cl-loaded rabbits, DIDS eliminated HCO3- reabsorption, a result consistent with known effects of DIDS as an inhibitor of H+ secretion. In contrast, cAMP left acidification (H+ secretion) intact. DIDS applied to HCO3- secretory tubules failed to increase the HCO3- secretory rate, indicating minimal H+ secretion in HCO3- secreting tubules. Thus, inhibition of H+ secretion by cAMP could not account for the cAMP-induced stimulation of net HCO3- secretion. cAMP-stimulated HCO3- secretion was reversibly eliminated by 0 Cl perfusate, whereas luminal DIDS had no effect. Bath amiloride (1 mM) failed to eliminate cAMP-stimulated HCO3- secretion when bath [Na+] was 145 mM or 5 mM. cAMP depolarized the transepithelial voltage. The collected fluid [HCO3-] after cAMP could be accounted for by electrical driving forces, suggesting that cAMP stimulates passive HCO3- secretion. However, cAMP did not alter HCO3- permeability measured under conditions expected to inhibit transcellular HCO3- movement (0 Cl- solutions and bath DIDS). This measured HCO3- permeability was not high enough to account, by passive diffusion, for the HCO3- fluxes observed in Cl- containing solutions. We conclude the following: 1) cAMP increased net HCO3- secretion by stimulating HCO3- secretion and not by inhibiting H+ secretion; 2) this HCO3- secretion may have occurred by Cl-HCO3- exchange; 3) Na+-H+ exchange appeared not to play a role in basolateral H+ extrusion under these conditions; and 4) the stimulation of HCO3- secretion by isoproterenol, but not ADH, suggests the existence of separate cell cAMP pools or cellular heterogeneity in this cAMP response.

UR - http://www.scopus.com/inward/record.url?scp=0022363306&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=0022363306&partnerID=8YFLogxK

M3 - Article

C2 - 2989340

AN - SCOPUS:0022363306

VL - 75

SP - 2056

EP - 2064

JO - Journal of Clinical Investigation

JF - Journal of Clinical Investigation

SN - 0021-9738

IS - 6

ER -