Acute effects of epidermal growth factor on Na+, K+-ATPase-dependent oxygen consumption and the amount of the enzyme units in enterocytes isolated from the jejunum of chickens

Enterocytes from jejunum of male White Leghorn chickens aged 14 d and 20 wk were used to investigate the short-term effect of epidermal growth factor (EGF) on total O-2 uptake (TO2) and Na+, K+-dependent O-2 uptake (OSO2) and intracellular pH (pHi). Total O-2 uptake and OSO2 was decreased (P < 0.05) in enterocytes, isolated from both young and adult birds as concentration of EGF increased in the incubation medium from 0 to 100 ng mL(-1). The ener gy required to support Na+, K+-ATPase activity in jejunal enterocytes obtai ned from 2-wk-old and 20-wk-old birds was 33-37% and 31-34% of total O-2 up take, respectively. No changes were observed in the amount of the maximal b inding sites for H-3-ouabain in enterocytes incubated with EGF; the regulat ion had not caused rapid decrease in the amount of Na+, K+-ATPase units in the basolateral membrane of enterocytes. Epidermal growth factor caused sho rt-term reduction of pHi as did amiloride. Seemingly, an acute action of EG F in chicken enterocytes in vitro is to reduce the activity of a fixed numb er of Na+,K+-ATPase units in enterocytes by decreasing Na+, H+-antiport-dep endent Na+ influx.