The purpose of the present investigation was to study the excretion by the foetal kidney of the sheep of three normal components of foetal sheep blood, namely glucose, fructose and meso-inositol. Evidence has been put forward that in man these substances share some common element of the reabsorptive mechanism; thus Gammeltoft & Kjerulf-Jensen (1943) have suggested that glucose and fructose compete, while Daughaday & Larner (1954) suggested a common mechanism for glucose and meso-inositol.The results reported here indicate that glucose reabsorption is well established in the foetus by the middle of gestation, whereas fructose and mesoinositol are only poorly reabsorbed.
METHODSStudies were made on eight foetuses between 59 and 135 days gestation age. The foetuses were delivered by Caesarian section from Welsh ewes under procaine spinal anaesthesia, supplemented when necessary during the course of the experiment with intravenous thiopentone. The ewe was held in the supine position with the head and upper portion of the trunk elevated to an angle of about 450 above the horizontal. On delivery the foetus was placed on a heated platform fixed between the legs of the ewe. Care was taken to ensure that the cord was not under tension and that it was kept warm and moist. With older foetuses the head was initially delivered into a polythene bag containing 0 9 %O NaCl solution, to prevent the onset of breathing. Tributaries of the umbilical veins and arteries were catheterized for intravenous administrations and blood sampling respectively. Exposure and cannulation of the foetal bladder was carried out in the manner previously described (Alexander, Nixon, Widdas & Wohlzogen, 1958).Two lambs (10 hr and 7 days post-natal), were anaesthetized with intravenous thiopentone, the abdomen opened and the bladder cannulated directly. Catheters were inserted in the femoral vein and artery for administrations and blood sampling.In two adult ewes experiments have been performed under spinal anaesthesia, in which the bladder was either cannulated directly or by the urethral insertion of a catheter. Experiments have also been performed on the unanaesthetized ewes at intervals over several weeks. With aseptic techniques, amethocaine (10-15 mg in 2-5 ml. of 4-5 % glucose) was injected into the subarachnoid space immediately above the sacrum. Long polythene catheters (Allen and Hanbury Ltd., No. 2) fitted with two-way taps were inserted into the dorsalis pedis artery and vein so that the tips lay in the large vessels. The catheters were filled with heparin saline solution (5000 i.u. ml.). After suturing the skin and applying