The effect of hypophysectomy and prolactin treatment on the osmotic water influx into the isolated gills of the Japanese eel (Anguilla japonica)

Abstract

An in vitro technique has been used to measure the osmotic water influx into the isolated gills and the osmotic permeability of the gill surface of the Japanese eel, Anguilla japonica. Hypophysectomy increases both of these measurements. Prolactin injections decrease both osmotic water influx and osmotic permeability to water in both the intact and hypophysectomized eels in fresh water but produce no change in either of these parameters when the fish (either intact or hypophysectomized) are in sea water. The possible role of the pituitary (especially prolactin) in osmoregulation of fishes is discussed and considered in relation to the environmental calcium in sea water.