Renal Dead Space as a Function of Urine Flow in the Anesthetized Dog

Abstract

A procedure was devised for the calculation in experimental animals of the mean transit time of glomerular substances (e.g., inulin and creatinine in the dog) from the renal artery to the uretero vesical junction. The procedure is based on the indicator dilution method of Stewart and Hamilton and requires the determination in serial samples of urine of the amounts of the glomerular substance excreted following instantaneous injection into the renal artery. From the mean transit time and the observed flow of urine values are calculated for the renal dead space. The calculated dead space is approximately proportional to the rate of urine flow for rates of urine flow between 1 and 11 ml/min. It is pointed out that the mean transit time or the modal transit time, rather than the appearance time, may be more suitable in corrections for delay in conventional renal clearance studies.