The Renal Blood Flow 91 



of view of glomerular filtration or tubular excretion, is not 

 increased by hyperemia. 



I turn now to a brief discussion of renal function in sub- 

 jects with essential hypertension. Our investigations have 

 been in progress for several years^^ "^ and have been accom- 

 panied by a thorough clinical and X-ray study of the pa- 

 tients. Lack of space unfortunately precludes the inclusion 

 of history, physical examination, etc. The diagnosis of essen- 

 tial hypertension has been based upon the usual clinical cri- 

 teria, though a few subjects with history of renal lithiasis or 

 infection have been included, but no subject is included who 

 presented any history or signs suggestive of glomeruloneph- 

 ritis. 



In the earlier period of this study we had not yet de- 

 veloped the methods for measuring glucose-Tm and diodrast- 

 Tm, and consequently our information in this respect is not 

 as complete as we would wish. However, we have sufficient 

 information on these functions from our recent observations 

 to justify a tentative discussion. 



A summarizing chart, showing the more important data 

 on renal function as found in 15 hypertensive subjects, is 

 given in Figure 7. This chart includes only those subjects 

 who show 30 per cent or better of renal parenchyma still in- 

 tact. It is not implied that a seriatim comparison of various 

 individuals in this manner depicts the course of hypertensive 

 disease. It is simply a convenient physiological method of 

 analysis. At the left of the figure there are given our stand- 

 ard normal values for the renal plasma flow, filtration rate, 

 diodrast-Tm and filtration fraction."' 



*The average normal value of diodrast-Tm is based on only 14 normal subjects, the 

 other data on 34 normal subjects, some of whom have been examined repeatedly. These 

 standard values are not final and will be amended as rapidly as our observations on normal 

 subjects are expanded. 



