Influence of theophylline on the diameter of the afferent glomerular arteriole of the rat

After agar-agar and india ink mixture intrarenal injection, it is possible to measure precisely the glomerular afferent arteriole diameter and to evaluate its variations after theophylline perfusion. The increased diameter (+ 35.78%) confirms the peripheral vasodilating theophylline effect, often assumed, but never to our knowledge proven in situ.