DIRECT VASCULAR EFFECT OF ROPIVACAINE IN FEMORAL-ARTERY AND VEIN OF THE DOG

A study was conducted to examine the direct vascular effect of ropivac aine, in comparison with the effect of bupivacaine and lidocaine. Chan ges in tension induced by ropivacaine (10(-5)-3 x 10(-3) mol l-1), bup ivacaine (10(-5)-3 x 10(-3) mol l-1) and lidocaine (10(-5)-10(-2) mol l-1) were examined cumulatively in vascular rings of dog femoral arter y and vein under basal tension, or in those which had been precontract ed with phenylephrine submaximally in Krebs' bicarbonate solution at 3 7-degrees-C aerated with 95% O2 and 5% CO2 (pH 7.4). The change in ten sion induced by 10(-2) mol l-1 ropivacaine was tested under basal tens ion in vascular rings bathed in HEPES buffer (pH 6.8). Ropivacaine ind uced greater constriction than bupivacaine at concentrations over 10(- 3) mol l-1 in vascular rings under basal tension (P < 0.01). The maxim al contraction was induced by ropivacaine at 10(-3) mol l-1, averaging 51.5 +/- 2.8% (n = 11) and 27.0 +/- 3.7% (n = 12) of the maximal cont raction induced by epinephrine in the artery and vein, respectively, a nd the contractions induced by ropivacaine at 10(-2) mol l-1 were 16.3 +/- 2.0% (n = 11) and 5.5 +/- 1.1% (n = 9), respectively. Phenylephri ne (10(-6) mol l-1)-precontracted artery was contracted significantly by ropivacaine at 3 x 10(-4) mol l-1 and 10(-3) mol l-1, and by bupiva caine at 3 x 10(-4) mol l-1, whereas the phenylephrine (10(-6) mol l-1 )-precontracted vein was relaxed by these anesthetics. Lidocaine did n ot exert constricting effects. It is concluded that ropivacaine is a p otent vasoconstrictor, although its constrictive effect is slight at 1 0(-2) mol l-1, which may be relevant to the clinical local concentrati on.