Hormones and non-specific humoral factors in the interferences between sodium, glucose and phosphate handling by dog kidney.

Some relationships between renal handling of sodium, glucose and phosphate have been investigated comparatively in dog kidneys studied "in situ", transplanted to the neck vessels of a perfusor animal, or perfused by a pump-oxygenator machine. The results can be summarized as follows: a) The values of tm of glucose per ml of glomerular filtration rate are not significantly different in the presence or in the absence of a perfusor animal, thus ruling out an hormonal modulation. b) An identical curvilinear regression relation between tmG and fractional excretion of sodium is found in the three types of experiments; the response to saline loading is identical; therefore an hormonal control of extrarenal origin is excluded. The differences in the decrease of tm glucose at high or low values of sodium excretion seem best explained by a coupling between glucose transport and one component of sodium transport which should be comparatively less influenced when the impairment of proximal reabsorption is high. c) A competition between glucose and phosphate excretion is observed in the isolated kidney; therefore it depends also at least for some part on intrarenal mechanisms. d) Insulin decreases phosphate clearance by direct renal action, probably by enhancing the tubular reabsorption of this ion as well as of sodium.