[Depressive effect of dibucaine and bupivacaine on the growth of axons from cultured neuron of Lymnaea stagnalis].
The depressive effect of dibucaine (n = 8) was compared with that of bupivacaine (n = 9) using identified cultured neurons (A cluster) of Lymnaea stagnalis. Cultured interneurons exhibit extensive neurite outgrowth within 14-20 hours when placed in brain conditioned media. The changes of cultured neuron were recorded using a color video camera directly connected to an inverted microscope and the images were stored on digital video tape. Local anesthetics were added to the culture dish, with final concentrations of 1 x 10(-6) M-8 x 10(-4) M of dibucaine and 1 x 10(-5) M-8 X 10(-3) M of bupivacaine. We examined the damage of growth cone before and 30 minute after local anesthetics administration. Histologic damage were scored from moderate to severe compared to the control before dibucaine or bupivacaine administration. Dibucaine or bupivacaine damaged the growth cone moderately in the concentration of 1 x 10(-5) M or 4 x 10(-4) M, respectively. While dibucaine or bupivacaine damaged it severely in the concentration of 8 x 10(-5) M or 2 x 10(-3) M, respectively. These results suggest that bupivacaine is safer than dibucaine with the concentration we use in clinical practice.