Effect of vasopressin as a local anesthetic in mice

We sought to elucidate how the local administration of mepivacaine hydrochloride and vasopressin via the tail affects the peripheral blood flow volume, tissue dynamics, and mepivacaine’s anesthetic effect in mice. Two-hundred and twenty-six male ICR mice were used in this study. Blood flow was measured after administering mepivacaine alone or mepivacaine with either 0.03, 0.3, or 3.0 U/mL vasopressin or 10 µg/mL epinephrine via the tail tissue. The tail tissue and blood dynamics were measured using ³H-labeled mepivacaine hydrochloride with vasopressin or epinephrine. The compound nerve action potential (CNAP) was measured to clarify the anesthetic effect after administering mepivacaine with 0.3 U/mL vasopressin. The statistical methods employed were Steel–Dwass test, Mann–Whitney U test, Dunnett’s test, and Tukey test. P < 0.05 indicated statistical significance. The results revealed that the local administration of ≥ 0.03 U/mL vasopressin reduced local blood flow and prolonged ³H-M localization in the tail tissue in a concentration-dependent manner. Addition of 0.3 U/mL vasopressin enhanced and prolonged the anesthetic effect of mepivacaine. The findings suggest that adding vasopressin to a local anesthetic regimen may be effective, and thus it could be applied as a vasoconstrictor.