Protein kinases participate in the contraction in response to levobupivacaine in the rat aorta

Abstract

Levobupivacaine is a long-acting amide local anesthetic that intrinsically produces vasoconstriction both in vivo and in vitro. Levobupivacaine increases intracellular calcium concentrations ([Ca2+]i) in vascular smooth muscle cells. The goals of this in vitro study were to investigate whether levobupivacaine-induced contraction is associated with increased Ca2+ sensitivity and to identify the protein kinases involved in mediating contraction in response to levobupivacaine in isolated rat aortic smooth muscle. The effect of levobupivacaine and potassium chloride (KCl) on the [Ca2+]i and tension was measured simultaneously with acetoxymethyl ester of fura-2-loaded aortic strips. Cumulative levobupivacaine concentration–response curves were generated in the presence or absence of the following antagonists: GF 109203X; Y-27632; genistein; SP600125; PD 98059; and SB 203580. Levobupivacaine-induced protein kinase C (PKC), extracellular signal-regulated kinase (ERK), and c-Jun NH2-terminal kinase (JNK) phosphorylation and Rho-kinase (ROCK-2) membrane translocation were detected in rat aortic vascular smooth muscle cells using Western blotting. The slope of the [Ca2+]i-tension curve for levobupivacaine was higher than that for KCl. Y-27632, GF 109203X, and SP600125 attenuated levobupivacaine-induced contraction in a concentration-dependent manner. Genistein, PD 98059, and SB 203580 attenuated levobupivacaine-induced contraction. Pretreatment with GF 109203X and Y-27632 inhibited levobupivacaine-induced PKC phosphorylation and Rho-kinase (ROCK-2) membrane translocation, respectively. Pretreatment with SP600125 or PD 98059 attenuated the levobupivacaine-induced phosphorylation of JNK and ERK, respectively. These results indicate that levobupivacaine-induced contraction involving an increase in myofilament Ca2+ sensitivity involves the primary activation of Rho-kinase-, PKC-, and JNK-mediated pathways of rat aortic smooth muscle.