PYELONEPHRITIS - RENAL UROKINASE AND SIALIDASE (NEURAMINIDASE) ACTIVITY IN RATS FED A STANDARD LABORATORY DIET

Renal stone formation can be caused by many different and varied distu rbances, some of which are poorly understood. The relationship between urinary infection and renal stone formation has not been completely c larified. It is argued that renal stones form primarily as a consequen ce of the hydrolysis of urea by the bacterial enzyme urease. However, no explanation is given for microorganisms that produce urease only oc casionally or not at all. The question arises as to whether the infect ion-induced microorganisms might not be playing a double role in renal stone formation by not only producing urease, but also by affecting i n vivo urokinase (UK) and sialidase (SA) activity. With this in mind, the effect of Escherichia coli on renal UK and SA activity has been st udied in male rats with a normal diet. The renal UK (P = 0.208) and SA (P = 0.2135) activities did not differ significantly between the two kidneys of the same rat. In contrast, when drainage from one kidney of a rat was externally obstructed, the UK and SA activities differed si gnificantly between kidneys (P<0.015). An increase in UK (r = 0.6456, P<0.0001) and SA (r = 0.7507, P<0.0001) activity was observed over tim e in the obstructed kidney. Subcutaneous injections with E. coli reduc ed the UK activity of the obstructed kidney significantly (p = 0.0171) . However, the SA activity remained the same (P = 0.3929). This decrea se in the UK activity in the presence of microorganisms may result in an increase in the uromucoid concentration, leading to renal stone for mation in the presence of increased salt precipitation on the uromucoi d as caused by the urease producing microorganisms.