Effect of SWL on renal hemodynamics: could a change in renal artery contraction-relaxation responses be the cause?

The aim of this study was to reveal the effect of shock wave lithotripsy (SWL) on renal artery contraction-relaxation responses and the relation of this effect with renal hemodynamics. Twenty-four rabbits are divided into six different groups. The first two groups evaluated as the control groups. After isolating the kidneys, we applied phenylephrine (Ph) and acetylcholine (Ach) in the first group and sodium nitroprusside (SNP) and histamine (H) in the second group. In the third, fourth, fifth and sixth groups, 14.5 kV shock wave (SW) was focused on the left kidneys. We adjusted the number of shocks to a total of 500, 1,500, and 3,000 SW, in the third, fourth and fifth groups, respectively. After isolating the kidneys, Ph, Ach was given in groups 3, 4 and 5. In the sixth group, to get the SNP and the H responses, 3,000 shocks modality was utilized. Marked contractile responses were obtained by phenylephrine in the control group. In kidneys that were exposed to 500 shocks SWL procedures, a decrease in contractile responses and hence, in perfusion pressures in different concentrations of phenylephrine was noted. However, a notable change in relaxation responses occurred after 3,000-shock applications. No difference in relaxation responses to nitroprusside, a direct vasodilating agent, was observed in any group, compared to the control group. Another cause of deterioration of renal hemodynamics after SWL can be attributed to the reduction in renal artery contraction-relaxation responses that result in the vascular smooth muscle and endothelial damage.