Adenosine modulation of resting vascular tone in rabbit skeletal muscle

The effects of adenosine and adenosine antagonists on arteriolar vessel diameters were studied in the rabbit tenuissimus muscle in situ by means of intravital microscopy. Topically applied adenosine dose-dependently dilated transverse and terminal arterioles, an effect which was competitively antagonized by alkylxanthines. Topically applied alkylxanthines per se evoked dose-dependent vasoconstriction with the same potency order as for their adenosine antagonism. Furthermore, the concentrations of alkylxanthines eliciting vasoconstriction correlated with the observed pA2 values for their adenosine antagonism. The data indicate a physiological role of adenosine, or other purines, as regulator of resting vascular tone in mammalian skeletal muscle.