Direct evidence for myogenic autoregulation of the renal microcirculation in the hamster.

We transplanted neonatal hamster renal tissue into a hamster check pouch chamber and subjected the renal tissue to increases and decreases in extravascular pressure. A decrease in extra-vascular pressure decreased, and an increase in extravascular pressure increased, the diameter of preglomerular arterioles. Thus, the change in preglomerular arteriolar diameter was directly related to alterations in extravascular pressure. Neither saralasin nor indomethacin affected these changes, whereas papaverin prevented them. The efferen arterioles responded passively to changes in extravascular pressure; i.e., the changes in their diameter were inversely related to changes in extravascular myogenic autoregulation of preglomerular vessels.