Prostaglandin in regulations of renal blood flow during partial ureteral obstruction in dogs

Ureteral obstruction causes increase in renal blood flow (RBF) and partial impairment of the autoregulation of RBF. Although increased renal prostaglandin production is responsible for the former, it is not clear whether or not it is also responsible for the latter. Therefore, we investigated the role which prostaglandins play in the autoregulation of RBF during an ureteral pressure elevation (40 cmH2O). Since the major mechanism of RBF autoregulation is the tubuloglomerular feedback studying the interaction between ureteral pressure and RBF autoregulation may reveal the role of prostaglandin in tubuloglomerular feedback. To pursue the purpose, six anesthetized dogs were prepared for the measurements of RBF, mean systemic and renal arterial pressure (RAP) and the manipulation of ureteral pressure. The autoregulation curves were determined during both control and elevation of the ureteral pressure, before and after the pretreatment with indomethacin, a cyclooxygenase inhibitor. The desired ureteral pressure was achieved by vertically elevating the water-filled reservoir connected to the ureteral catheter to 40 cm above the kidney level. In response to the elevation of the ureteral pressure, RBF increased from 170 +/- 8 ml cntdot min -1 to 189+/-8, and the systemic arterial pressure didn't change significantly. During spontaneous urine flow, RBF autoregulation was abolished when RAP was reduced to 59+/-3 mmHg. On the other hand, during the ureteral pressure elevation, the autoregulation curves shifted upward and rightward from control, and the pressure when RBF autoregulation was abolished was 74 +/- 3 mmHg. The pretreatment of the dogs with indomethacin failed to affect the lower limit of RBF autoregulation during both control (63 +/- 5 mmHg) and the elevated ureteral pressure (77 +/- 5 mmHg). Since RBF failed to increase in response to the elevated ureteral pressure, RBF autoregulation curves obtained during the elevated ureteral pressure shifted only rightward from indomethacin control. The results indicate that the increased intrarenal level of prostaglandin or prostaglandin-induced vasodilation does not appear to bear any relation to the reduction in the autoregulatory capacity during partial ureteral obstruction. It seems that the partial impairment of the autoregulation during acute ureteral obstruction is due to the consumption of tubuloglomerular feedback mechanism at spontaneous RAP and that prostaglandin is neither mediator nor effector of tubuloglomerular feedback mechanism.

The Effect of Vecuronium on Intraocular Pressure / 대한마취과학회지

Thirty healthy patients were studied to evaluate the effect of muscle relaxants on intra-ocular pressure (IOP) during anesthesia. The patients were divided intro three groups-succinrlcholine group(Img/k7,n=10) , pancu-ronium group(0.08mg/kg,n=10), and vecuronium group(0, Img/kg,n=10) according to the muscle relaxants used. All patients were premedicated with robinul 0.2mg and lorazepam 4mg one hour before surgery. Tracheal intubation was fellowed by thiopental sodium 5mg/ kg and muscle relaxant. Anesthesia was maintained with O2-N2O-enflurane and respiration and was controlled by anesthetic ventilator (Dameca). The lOP was measured hy Schotz tonometer, before induction of anesthesia, at 75~100% depression of twitch height on train of-four after injection of muscle relaxant, and at 1,3, 5, 10, minutes after intubation respectively. Heart rate, mean arterial pressure, and end-tidal CO2 tensions were also measured simultaneously. The results were as follows ; 1) At 75~100% depression of twitch height, IOP wart elevated significantly in succinylc-holine group but reduced significantly in both pancuronium and vecuronium groups as Compared With pre induction value. 2) IOP was elevated in all groups after 1 minute of intubation, there were no statistical significance in pancuronium or vecuronium group as compared with pre induction value. After 3 minutes of intubation, IOP was reduced in all groups in proportion to the depth of anesthesia. 3) Cardiovascular changes in vecuronium group were less than those in succinrlcholine or pancuronium group. In conclusion vecuronium, with less cardiovascular changes, may be indicated for anest-hesia of open eye injury compare other muscle relaxants.