HEXOSE ACCUMULATION BY ENTEROCYTES FROM THE JEJUNUM AND RECTUM OF CHICKENS ADAPTED TO HIGH AND LOW NACL INTAKE

We have studied the effects of adaptation to low NaCl intakes on hexos e transport using suspensions of enterocytes isolated from the jejunum and the rectum of the chicken. Animals (12-13 weeks old) were kept fo r 11 days on either a high-Na+ (HS) or a low Na+ (LS) diet. On day 11 mean serum aldosterone concentration was 46 pg/ml in HS birds and 236 pg/ml in LS birds. Results of transport studies show that: (1) adaptat ion to a LS diet reduces the cellular 3-oxymethyl-D-glucose cumulative capacity by 40% in the jejunum and is virtually abolished in the rect um; (2) LS adaptation reduces initial alpha-methyl-D-glucoside influx (1 mmol/l) by 22% in the jejunum and by 54% in the rectum; (3) the inf lux of the membrane potential sensor tetraphenyl-phosphonium (TPP+) in enterocytes strongly suggests that rectal cells of LS birds are signi ficantly depolarized; (4) the presence of 0.1 mmol/l amiloride increas es the capacity of the rectal cells of LS birds to establish a sugar g radient across the membrane; (5) incubation of enterocytes with cytoch alasin B increases sugar cumulative capacity of the jejunal cells of b oth HS and LS birds, and has no effect on the rectal cells of LS birds . We conclude that the effects of LS adaptation on sugar transport may involve a reduction in the membrane electrical potential.