title: Brain natriuretic peptide stimulates K and Cl secretion across porcine distal colon epithelium.
abstract: Porcine distal colon epithelium was mounted in Ussing chambers and bathed with porcine Ringer solution. The serosal addition of brain natriuretic peptide (BNP; 50 nM) or atriopeptin III (AP-III; 500 nM) produced significant increases (50-75 microA/cm2) in short-circuit current (Isc). These increases in Isc were not inhibited by pretreatment with tetrodotoxin (TTX) or 5,8,11,14-eicosatetraynoic acid (ETYA). Analysis of concentration-response relationships revealed that BNP was 5.8-fold more potent than AP-III in stimulating the Isc. BNP and AP-III significantly increased the serosal-to-mucosal (S----M) Cl flux and reduced net Cl absorption by 38 and 41%, respectively. The BNP-stimulated S----M Cl flux was abolished when HCO3 was removed. In contrast, the vasoactive intestinal peptide (VIP)-stimulated S----M Cl flux was not affected by HCO3 replacement. In addition to their effects on Cl transport, BNP and AP-III increased net Rb secretion by 79 and 58%, respectively. BNP-stimulated Rb secretion was reduced by 76% after HCO3 replacement. These results indicate that natriuretic peptides stimulate K- and HCO3-dependent Cl secretion which is not present under basal conditions or after VIP stimulation. The difference in potency between BNP and AP-III suggests that ANP-B receptors may mediate their effects on ion transport in the porcine colon.
authors.affiliation: Department of Veterinary Biology, University of Minnesota, St. Paul 55108.
authors.forename: T R
authors.initials: TR
authors.lastname: Traynor
authors.forename: S M
authors.initials: SM
authors.lastname: O'Grady
mesh_terms: D015117:5,8,11,14-Eicosatetraynoic Acid / Q000494:pharmacology; D000595:Amino Acid Sequence; D000818:Animals; D009320:Atrial Natriuretic Factor / Q000494:pharmacology; D001639:Bicarbonates / Q000494:pharmacology; D002712:Chlorides / Q000378:metabolism*; D003106:Colon / Q000187:drug effects / Q000502:physiology*; D004848:Epithelium / Q000187:drug effects / Q000502:physiology; D066298:In Vitro Techniques; D007700:Kinetics; D008969:Molecular Sequence Data; D009130:Muscle, Smooth / Q000187:drug effects / Q000502:physiology*; D020097:Natriuretic Peptide, Brain; D009419:Nerve Tissue Proteins / Q000494:pharmacology*; D011188:Potassium / Q000378:metabolism*; D051381:Rats; D012689:Sequence Homology, Nucleic Acid; D013552:Swine
chemical_list: D001639:Bicarbonates; D002712:Chlorides; D009419:Nerve Tissue Proteins; D020097:Natriuretic Peptide, Brain; D015117:5,8,11,14-Eicosatetraynoic Acid; D009320:Atrial Natriuretic Factor; D011188:Potassium