Development of H+ secretion by cultured renal inner medullary collecting duct cells.
The purpose of these studies was to characterize the development of H+ secretion by cultured inner medullary collecting duct (IMCD) cells. Differentiated IMCD cells derived from rat papillae develop in culture N-ethylmaleimide (NEM)- and dicyclohexylcarbodiimide (DCCD)-sensitive Na+-independent H+ pump, but showed substantial heterogeneity. Cells with pHi greater than or equal to 7.1, measured by 2',7'-biscarboxyethyl-5(6)-carboxyfluorescein (BCECF), showed more H+ pumping than did those with pHi less than 7.1. Quiescent cells in domes and in the center of growing nests often showed active H+ pumping activity, but rarely exhibited Na+-H+ exchange, whereas dividing cells at the periphery of the nests showed only Na+-H+ exchange. Differentiated IMCD cells also showed Na+-independent 4,4'-diisothiocyanatostilbene-2,2'-disulfonic acid (DIDS)-sensitive Cl(-)-HCO3- exchange that functioned best when pHi was greater than or equal to 7.1, and homogenates of IMCD cells expressed carbonic anhydrase (CA) activity and CA II mRNA. A subgroup of IMCD cells avidly bound fluorescent peanut agglutinin (PNA); this binding became more extensive with time in culture. The PNA-labeled cells showed increased BCECF uptake, higher pHi, and more H+ pumping activity than did cells not binding PNA. They could be isolated by gel-immobilized PNA and in culture showed more CA activity and H+ pumping activity than unselected monolayers. The percentage of cells binding PNA correlated well with CA activity, indicating that this subgroup is better specialized to secrete H+. The appearance of PNA binding sites and the development of high CA activity may be characteristic of IMCD cell differentiation in culture.
Brion
L P
LP
Department of Pediatrics, Albert Einstein College of Medicine, Bronx, New York 10461.
Schwartz
J H
JH
Lachman
H M
HM
Zavilowitz
B J
BJ
Schwartz
G J
GJ
D000818:Animals; D010367:Arachis; D002256:Carbonic Anhydrases / Q000235:genetics / Q000378:metabolism; D002352:Carrier Proteins / Q000378:metabolism; D002417:Cattle / Q000196:embryology; D002478:Cells, Cultured; D027963:Chloride-Bicarbonate Antiporters; D005312:Fetal Blood / Q000502:physiology; D006859:Hydrogen / Q000378:metabolism*; D006863:Hydrogen-Ion Concentration; D007473:Ion Channels / Q000502:physiology; D007679:Kidney Medulla; D007684:Kidney Tubules / Q000378:metabolism*; D007685:Kidney Tubules, Collecting / Q000166:cytology / Q000378:metabolism*; D037102:Lectins / Q000378:metabolism; D008940:Mitotic Index; D019887:Peanut Agglutinin; D037121:Plant Lectins; D012333:RNA, Messenger / Q000378:metabolism; D017923:Sodium-Hydrogen Exchangers; D013997:Time Factors
D002352:Carrier Proteins; D027963:Chloride-Bicarbonate Antiporters; D007473:Ion Channels; D037102:Lectins; D019887:Peanut Agglutinin; D037121:Plant Lectins; D012333:RNA, Messenger; D017923:Sodium-Hydrogen Exchangers; D006859:Hydrogen; D002256:Carbonic Anhydrases