THE EFFECT OF SINGLE SHOCK-WAVES ON THE VASCULAR SYSTEM OF ARTIFICIALLY PERFUSED RABBIT KIDNEYS

Extracorporeally-perfused rabbit kidneys were exposed to five shock wa ves at 14 kV on the XL1 Dornier experimental lithotripter (Dornier Med ical Systems, Inc., Germering, Germany). While the perfusion flow rate was kept constant, the arterial perfusion pressure was recorded to as sess changes in vascular resistance. Immediately after shock wave appl ication, perfusion pressure decreased by 20%-30%, followed by a short, relative pressure rise that did not reach pretreatment values. Fiftee n-twenty minutes later, arterial perfusion pressure reattained pretrea tment values. Subsequent to treatment, urine flow decreased by > 50%. The observed pressure rise was also induced in nontreated kidneys by p erfusion with the effluent of treated kidneys indicating that this is based on a humoral mechanism. On the other hand, shock wave applicatio n to formalin fixed kidneys only caused a marked decrease in arterial perfusion pressure, suggesting that this effect is due to a pure mecha nical interaction of the shock wave also found with denaturated kidney s. The observed decrease of urine flow is probably caused by a decreas ed filtration rate. Since this was not the case in nontreated kidneys being perfused with the effluent of treated kidneys, the reduction of urine flow after extracorporeal shock wave lithotripsy does not appear to be mediated by a humoral factor, but is more likely a result of th e mechanically-induced vasodilation with consecutive decline of the gl omerular filtration rate.