A new device for differentiated tissue sampling in rat kidney.

Since freeze-clamping does not allow to sample the diffrent renal areas a new method of kidney tissue sampling in anesthetized rats is described. It consists in sectioning a slice in the middle of the rat kidney and immediately freezing. This device allows quick and accurate separation of the different renal areas, and especially of the papilla which is almost entirely sampled. Complete freezing is obtained within 7s after clamping of the renal artery. As proof of adequate "in vivo" fixing, adenine nucleotide levels were assessed in each tissue sample. ATP concentration in cortex samples was 1.62 +/- 0.33 mumole/g wet tissue, this value is comparable with those obtained in the cortex by freeze-clamping.