Chloride transport in primary cultures of rabbit colonocytes at different stages of development.
OBJECTIVE
Ontogeny of colonic Cl- transport and its regulation has been characterized inadequately. The aim of this report was to study developmental changes in Cl- transport in primary cultures of rabbit distal colonocytes.


METHODS
Colonocytes from newborn (7-9 days old), weanling (25-28 days old), and adult (6 months old) rabbits were cultured for 24 hours on a collagen IV matrix, and Cl- transport was measured using the fluoroprobe 6-methoxyquinolyl acetoethyl ester.


RESULTS
Cl- permeabilities were dependent on [Cl-]o with maximal rates (in millimoles per liter per second) at [Cl-]o = 75 mmol/L (newborns; 0.15 +/- 0.04; weanlings; 0.2 +/- 0.02; and adults, 0.32 +/- 0.06). Influx was inhibited significantly by the Cl- channel (50 mumol/L diphenylamine-2-carboxylate) and the Na(+)-K(+)- 2Cl- cotransport (10 mumol/L furosemide) inhibitors. The adenosine 3',5'-cyclic monophosphate (cAMP)-dependent secretagogues, prostaglandin E1 (1 mumol/L), forskolin (1 mumol/L), and 8-bromo-cAMP (100 mumol/L), and the protein kinase C activator, phorbol 12-13 dibutyrate (1 mumol/L), increased Cl- influx significantly in all groups with adults showing greatest stimulation. However, taurodeoxycholate (0.025-1 mmol/L) had an effect only in the adult and the guanosine 3',5'-cyclic monophosphate (cGMP) activators STa and 8-bromo-cGMP had no effect.


CONCLUSIONS
Rabbit distal colonocytes possess inhibitor-sensitive Cl- permeabilities even in neonates. However, the ontogeny of their regulation depends on the secretagogue-signaling pathway.
Desai
G N
GN
Department of Pediatrics, University of Illinois at Chicago, USA.
Sahi
J
J
Reddy
P M
PM
Venkatasubramanian
J
J
Vidyasagar
D
D
Rao
M C
MC
D000818:Animals; D002478:Cells, Cultured; D002712:Chlorides / Q000378:metabolism*; D003106:Colon / Q000196:embryology / Q000378:metabolism*; D017136:Ion Transport; D011817:Rabbits; D015398:Signal Transduction
D002712:Chlorides