Influence of H+ on K+ on adenosine-induced dilatation at pial arteries of cats.

The influence of changes in the perivascular K+ and H+ concentrations upon adenosine-induced dilatations of pial arteries was investigated by localized perivascular application using micropuncture technique. Adenosine (10(-9)-10(-3) M) was dissolved in mock spinal fluids with varying bicarbonate and potassium concentrations (5 and 22 mM HCO3-, and 6 and 10 mM K+). Concentration response curves revealed that adenosine induced the same change in pial arterial diameter when dissolved either in an inert (11 mM HCO3-) or in a constrictory (22 mM HCO3-) mock spinal fluid. However, adenosine, when dissolved in a more acidic or higher potassium-containing solution (5 mM HCO3-, or 6 or 10 mM K+) produced a diminished dilatatory effect. It is concluded that, for a quantification of the individual contributions of several metabolic factors in the regulation of vascular resistance, it is necessary to consider their interactions.