Effects of lidocaine on rat’s isolated tracheal smooth muscle

Abstract

Lidocaine has been used as an injection or spray solution to protect spasm reaction during tracheal intubation and bronchoscopy. The effect of lidocaine for local anesthesia is well known. However, the effect of the drug to tracheal smooth muscle is not well explored. We used our preparation to test the effectiveness of lidocaine on rat's isolated tracheal smooth muscle. The following assessments of lidocaine were performed: (1) effect on tracheal smooth muscle resting tension; (2) effect on contraction caused by 5 x 10(-6) M methacholine as a parasympathetic mimetic; (3) effect of lidocaine on electrically induced tracheal smooth muscle contractions. The addition of lidocaine induced a relaxation response to methacholine-induced contraction. Low doses of the drug resulted in a slight decrease in contraction and higher doses relaxed the trachea much more quickly. At 10(-3) M of lidocaine, almost 51% of 5 x 10(-6) M methacholine-induced contraction was decreased. Using the same concentration, the drug also could totally inhibit the electrical field stimulation-induced spike contraction. Lidocaine elicited a negligible response to the resting tension of trachea as the concentration increased. The study indicated that lidocaine could cause bronchodilation not only from blocking parasympathetic tone, but also from directly antagonizing the effect of cholinergic receptors.

Effects of levobupivacaine on isolated rat tracheal smooth muscle

“…The findings on the dose-dependent protective effects of levobupivacaine against methacholine-induced contraction are consistent with the results obtained using lidocaine and bupivacaine [4,5,7,10,12]. A first possibility is that levobupivacaine may antagonize the effect of cholinergic agents.…”

“…Studies have used guinea pig trachealis to demonstrate that bupivacaine produces a biphasic response, exhibiting contraction at low concentrations and relaxation at high concentrations [11]. However, our recent studies have shown that these two local anesthetics did not lead to a significant change in resting tension [4,5]. In this investigation, levobupivacaine exerted a minimal effect on the basal tension as the concentration increased.…”

“…Levobupivacaine caused dose-dependent relaxation in the trachealis muscle precontracted with 10 −6 M methacholine. Contraction inhibition was statistically significant when 10 −5 and 10 −4 M levobupivacaine were applied, compared Methacholine can induce a dose-dependent contraction of a tracheal strip, and a concentration of 10 −6 M results in a significant degree of contraction [4]. Before drug assays were conducted, isolated tracheal samples were equilibrated in the bath solution for 30 to 45 min.…”

In vivo Comparison of the Effects of Bupivacaine and Levobupivacaine on the Pregnant Rat Myometrium Using Electrohysterogram

“…In their study, Arici et al [1] compared the effects of bupivacaine, ropivacaine and mepivacaine on the myometrial contractile activity, and found that bupivacaine and ropivacaine significantly inhibited the myometrial activity, whereas mepivacaine increased contractile activity with similar concentrations. Kao et al [6] investigated the effects of lidocaine on isolated rat tracheal smooth muscle, and they showed that lower doses led to decreased contraction, and higher doses caused faster relaxation. In the same study, lidocaine was determined to reduce the contraction induced by methacholine.…”

“…Studies conducted regarding the effects of lidocaine and bupivacaine on smooth muscles have shown that lidocaine caused a decrease in the contractility of the tracheal smooth muscles, whereas bupivacaine had the same effect on the myometrium [1,6]. Direct effects of local anesthetics are only seen at toxic doses and they cause tetanic contractions.…”