EXOGENOUS ADENOSINE INDUCES FLOWMOTION IN SKELETAL-MUSCLE MICROCIRCULATION OF THE ANESTHETIZED RAT

The aim of this study was to investigate the characteristics of the microcirculatory blood flow with laser-Doppler flowmetry (LDF) in skeletal muscle during both regional and systemic infusions of adenosine. A laser-Doppler flowmeter probe was placed on the left gastrocnemius muscle in anesthetized rats. Adenosine was given either systemically in the jugular vein (group A) or administered regionally in the iliac artery (group B). The infusion of adenosine was increased stepwise by 50 mu g/kg/min, every 10 min, up to 400 mu g/kg/min. In group A there was a dose-dependent decrease in mean arterial pressure as well as in LDF flow; flowmotion of the LDF signal with a frequency of 1.6 cycles/min was seen at a mean adenosine dose of 240 mu g/kg/min at a blood pressure of 60 mm Hg. In group B there was a dose-dependent decrease of mean arterial blood pressure but not as marked compared to group A, meanwhile the LDF flow was unchanged; flowmotion was seen at a mean adenosine dose of 220 mu g/kg/min at a blood pressure of 72 mm Hg, with a frequency of 1.5 cycles/min. This study demonstrates that adenosine, given either regionally intraarterially with maintained blood flow, or intravenously with reduced blood flow, induces flowmotion in skeletal muscle microcirculation with a frequency of approximately 1.5 cycles/min.