Abstract
The isolated perfused rat kidney has proven to be a very useful model for the assessment of the intrinsic renal actions of agents in a setting devoid of extrarenal influences (for review see [1]). A cell-free artificial medium of defined composition is employed usually for reasons of economy, as well as experimental design. The low viscosity of such media results in relatively high perfusate flow rates. The small size of the renal artery of the rat dictates the use of small-bore arterial cannulas that exhibit a significant resistance and induce a large decrement in pressure at the high flow rates encountered with this preparation. Since perfusion pressure is routinely monitored proximal to the arterial cannula, the pressure drop imposed by the cannula represents a potential source of error in the estimation of renal perfusion pressure. Furthermore, since perfusion pressure is an important determinant of renal function, such an erroneous estimation of this parameter may alter observed renal function inadvertently, thereby confounding the interpretation of results obtained with this model.
