Figure 1. Albumin clearance and plasma volume measured in C57BL6 mice with and without ANP.

A, the clearance of albumin in skin, muscle and trachea in wild type C57BL6 mice with no ANP (control; open bars) and C57BL6 mice with continuous infusion of ANP (0.5 ng min⁻¹ (g body weight)⁻¹; heavy hatched bars). The 30 min clearances were measured as the difference between the plasma equivalent volume containing the amount of albumin labelled with ¹²⁵I in the tissue (vascular plus extravascular space) after 35 min and the plasma equivalent volume of albumin labelled with ¹³¹I measured after 5 min (mainly vascular space, and also used as a measure of tissue plasma volume. B, the figure shows that the amount of albumin in the extravascular space after 30 min may be less than or equal to the amount of tracer in vascular space. There was a tendency for ANP to increase albumin clearances in all tissues but only back and tail skin and hamstring muscle showed significant increases (*P < 0.05) relative to vehicle control. There was no significant effect of ANP on measured plasma volumes (light hatched bars in B). All values are expressed per gram of tissue dry weight.