Figure 6. Diameters of arterioles that branched from primary and secondary arterioles in 7N, 18N, 7CH and 18CH rats.

Each column shows the mean ±s.e.m. Left- and righthand sets of columns show diameters of vessels that branched from primary arterioles (1°A) and secondary arterioles (2°A), respectively, the group of rats being indicated below the columns and by shading as in Fig. 3. **P < 0·01, significant difference between 7N and 7CH rats; *P < 0·05, significant difference between 18N and 18CH rats. n = 6 for each group, each value having been generated from the means of 10–20 measurements made in each of the right and left muscles of each animal.