The Effects of Heparin and Protamine on Contraction of Tracheal Smooth Muscle Induced by Carbachol in the Guinea Pig / 대한마취과학회지

BACKGROUND: Several reports have indicated that heparin has a bronchodilative effect in asthma patients, and that it enhances airway smooth muscle contraction in vitro, protamine is known to inhibit or enhance contraction of tracheal smooth muscle. Thus the effects of protamine and heparin on airway smooth muscle contraction are not consistent. However, no report is available on the effects of enflurane on heparin and protamine tracheal smooth muscle contraction. We performed this study to evaluate the effects of heparin or protamine on the carbachol induced contraction of tracheal smooth muscle in the guinea pig. And we also evaluated the effects of enflurane on heparin or protamine induced tracheal smooth muscle contraction. METHODS: Isolated tracheal rings of the guinea pig were suspended in Krebs solution. Contractions were recorded isometrically using a transducer. Contraction was induced by carbachol (10-6 M) and then cumulative dose responses of heparin or protamine (0.006 mg/ml, 0.02 mg/ml, 0.06 mg/ml, 0.2 mg/ml, 0.4 mg/ml) and in heparin (E) group and protmine (E) group, enflurane (4.34%) was administered for 15 minute after carbachol adminstration. RESULTS: Contraction by carbachol was inhibited by level of heparin or protamine at concentrations of 0.2 mg/ml and 0.4 mg/ml. At an enflurane (4.34%) contraction was inhibited, and no further inhibition of contraction by heparin or protamine was observed. CONCLUSIONS: Heparin or protamine inhibited the tracheal smooth muscle contraction induced by carbachol at 0.2 mg/ml and 0.4 mg/ml, and no further significant inhibition of contraction by heparin or protamine was observed after enflurane administration (4.34%).

Relaxant Effects of Thiopental, Ketamine, and Propofol on Isolated Rat Tracheal smooth Muscle / 대한마취과학회지

BACKGROUND: Intravenous anesthetics may modify airway responsiveness. The author investigated the relaxant effect of thiopental, ketamine, and propofol on isolated rat tracheal smooth muscles. METHODS: The trachea of the rat was dissected and cut into 3-mm rings. The rings were mounted in a water-jacked organ bath filled with Krebs solution aerated with 95% O2 and 5% CO2 at 37degreesC. Thiopental, ketamine, and propofol were given randomly to each ring preconstricted with EC50 of acetylcholine from 10(-6) to 10(-3) M. The relaxation response was the tension during anesthetic equilibration, expressed as a percentage of the tension from EC50 of acetylcholine. RESULTS: Thiopental and propofol (10(-5) to 10(-3) M) relaxed acetylcholine-induced contractions in a dose dependent manner (P < 0.05). Ketamine in doses of 10(-5) and 10(-4) M constricted acetylcholine-induced contractions by 3.2% and 16.5% respectively (P < 0.05). But ketamine in a dose of 10(-3) relaxed acetylcholine-induced contractions by 76.4% (P < 0.05). The relaxation of tracheal smooth muscles was greatest in thiopental, and was least in ketamine (P < 0.05). CONCLUSIONS: All three intravenous anesthetics have an excellent relaxation of tracheal smooth muscles in rats, except in doses of 10(-5) and 10(-4) M of ketamine.

Epithelial Modulation on Guinea-pig Tracheal Smooth Muscle Tension to Contractile Agents / 대한마취과학회지

BACKGROUND: Asthma can be described as the hypersensitivity of the airway to various stimuli. Injury to tracheal epithelial cells could be the reason for tracheal hypersensitivity in asthma or upper respiratory infection. This study is based on the hypothesis that the dysfunction of the airway in asthma is caused by epithelial cell injury. METHODS: After isolating guinea-pig tracheal preparations, in order to examine the role of airway epithelium in response to smooth muscle, we measured the contractile responses to acetylcholine, carbachol, and histamine on the isolated epithelium-denuded or epithelium-intact guinea-pig tracheal preparations. When tracheal tones were stabilized, each contractile agent was added cumulatively to the organ baths to obtain concentration-response curves, and ED50 and ED95 were calculated. RESULTS: In both groups, tracheal tones increased in response to contractile agents, in concentration- dependent manners. In comparing both groups, the contractility of denuded trachea was increased by 10 7 and 10 6 M in acetylcholine, and by 10 6 M in histamine significantly. In denuded trachea, ED50 and ED95 increased significantly in response to both acetylcholine and histamine. However, they did not increase in carbachol. CONCLUSIONS: The removal of the epithelium increased the contractile responses to acetylcholine and histamine.