To investingate the effects of fentanyl on the renal function and the renin secretion rate(RSR), the author measured the urine volume(UV), excreted amount of urinary sodium, potassium and chloride(UNaV, UKV, and UCLV), fractional excretion of sodium(FENa), renal plasma flow(RPF), glomerular filtration rate(GFR), filtration fraction(FF) and free water clearance(CH2O) after adminis- tration of fentanyl in 53 unanesthetized white rabbits. Fentanyl was given intrarenally(0.1ug/kg/min in group I, 0.3ug/kg/min in group II, and 1.0ug/kg/ min in group III), or intravenously(0.1ug/kg/min in group IV, 1.0ug/kg/min in group V, and 0.1ug/ kg/min in after preinfusion with naloxone 0.1ug/kg/min in group VI). After administration of fentanyl, urinary and plasma osmolalities and the levels of sodium, potas-sium, chloride, paraaminohippuric acid (PAH) and creatinine were measured. Heart rate (HR) and mean arterial pressure (MAP) were also measured. The results were as follows. 1) There were no statistically significant changes in HR and MAP in all groups. 2) The levels of UV, UNaV, UKV, VCIV, RPF and CH2O decreased significantly by low dose of fentanyl, not changed by moderate dose of fentanyl and the levels of UV and CH2O increased signifi-cantly by large dose of fentany. 3) Naloxone pretreatment blocked all of the observed renal responses of low dose of fentanyl. 4) There was no statistically signficant change in renin secretion rate in all groups. From the above results, it is suggested that the fentanyl has dual effects on the renal function and may have systemic effects through opioid receptors.
Arterial Pressure ; Creatinine ; Fentanyl* ; Filtration ; Heart Rate ; Naloxone ; Osmolar Concentration ; Plasma ; Potassium ; Rabbits* ; Receptors, Opioid ; Renin ; Sodium ; Water