Methods for studying an isolated renal microvessel.

Glomerular circulation is mainly regulated by two resistance arterioles, the afferent arteriole and the efferent arteriole. Many experimental findings show that each arteriole has a different sensitivity to various kinds of physiological stimuli and some vasoactive substances. Moreover, there is a regional heterogeneity of the glomerular microcirculation. Thus, many researchers have been challenged to develop direct studies that focus on the control of the renal microcirculation. The recent development of innovative in vivo and in vitro preparations provide the opportunity to directly study the renal microcirculation. In this article, we introduce the methods for isolation, cannulation and in vitro study of a single renal arteriole. The isolated renal microvessel technique permits direct in vitro assessment of single arteriolar responses in defined segments to vasoactive substances without the neurohumoral and parenchymal tissue environment. Intracellular ion concentration and functional change of the renal microvessel can be evaluated simultaneously using both this technique and fluorescent ion indicators. Accumulation of data that directly assesses the renal microcirculation may clarify mechanisms for the regulation of renal hemodynamics.