102 Physiology of the Kidney 



the conclusion that these lesions produce an elevation of 

 blood pressure. If the arterial change within the kidney is 

 sufficient to produce renal ischemia, however, hypertension 

 follows. Depending on the degree of renal arterial involve- 

 ment the hypertension may be 'benign' and senility ends with 

 mild circulatory difficulties and a beneficient broncho-pneu- 

 monia; more grave, and cardiac failure or cerebral accident, 

 depending on the condition of the local vessels, terminates in 

 more dramatic fashion life's last episode. 



"By such a concept it is not so much vascular senescence, 

 common to all organs and tissues, that determines the ulti- 

 mate outcome, but a disturbance within the kidney and pe- 

 culiar to its functions that is the final and actuating mechan- 

 ism of senile circulatory failure and accident. 



"A man's arteries may then be old, but only if his kidneys 

 are spared does his senescence approach the biological ideal 

 of a gradual and peaceful decline." 



This attractive view is, however, compKcated by the pos- 

 sibility that arteriolar sclerosis may itself be a result of pro- 

 longed hypertension rather than an initiating cause of the 

 disease.^^'^^ 



To read the rapidly expanding literature on this subject 

 is only to discover the complexity of the problem of ultimate 

 etiology. One observer holds that hypertension is of dietary 

 origin, while another relates it to climate, both interpreta- 

 tions being far from negligible since the incidence of the dis- 

 ease is remarkably low among many primitive peoples. By 

 other observers it is contended that there is a distinct heredi- 

 tary trend, at least in predisposition, while correlations with 

 endocrine imbalance, particularly of the gonads, are not 

 lacking. At the other extreme, the psychoanalysts tell us that 



