Figure 17.

Effects of prolonged adenosine infusion on blood flow on an isolated dog hindlimb preparation. Prior to adenosine infusion, electrically evoked skeletal muscle contraction caused an increase in blood flow. Adenosine was then infused for 150 min, and the vasodilator response to adenosine waned over that time. After the dilator response waned, the increase in blood flow to contractions was still present. The tachyphylaxis to adenosine indicated that skeletal muscle blood vessels had become desensitized to its vasodilator effects. The continued vasodilation with contractions after vasodilator responsiveness to adenosine had waned indicates that adenosine is not obligatory to generate a normal vasodilator response to contractions. [Adapted from Hester et al. (210).]