-Radford, L. M. 1998. 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. Can. J. Anim. Sci. 78: 327-333. 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 (TO 2 ) and Na + , K + -dependent O 2 uptake (OSO 2 ) and intracellular pH (pHi). Total O 2 uptake and OSO 2 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 energy required to support Na + , K + -ATPase activity in jejunal enterocytes obtained from 2-wk-old and 20-wk-old birds was 33-37% and 31-34% of total O 2 uptake, respectively. No changes were observed in the amount of the maximal binding sites for 3 H-ouabain in enterocytes incubated with EGF; the regulation had not caused rapid decrease in the amount of Na + , K + -ATPase units in the basolateral membrane of enterocytes. Epidermal growth factor caused short-term reduction of pHi as did amiloride. Seemingly, an acute action of EGF in chicken enterocytes in vitro is to reduce the activity of a fixed number of Na + ,K + -ATPase units in enterocytes by decreasing Na + , H + -antiport-dependent Na + influx.

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