Effects of sevo¯urane on sympathetic neurotransmission in human omental arteries and veins

Background. Sevo¯urane reduces blood pressure, the regulation of which requires an intact sympathetic neurotransmission. This study was designed to evaluate the effect of sevo¯urane on the coupling between peripheral sympathetic neurones and vascular smooth muscle in isolated human omental vessels. Methods. Segments of arteries and veins were exposed to sevo¯urane 1%, 2 % and 4% (corresponding to approximately 0.5, 1 and 2 MAC in humans, respectively). The vessels were studied in vitro to determine the effects on (i) isometric contraction during electrical ®eld stimulation (EFS) or in the presence of exogenous norepinephrine (NE); (ii) electrical ®eld stimulated release of [3H]-NE from vessel segments previously incubated with [3H]-NE; (iii) uptake of [3H]-NE. Results. In artery segments, sevo¯urane 4 % attenuated the contraction induced by both EFS and exogenous NE. In vein segments, sevo¯urane 4 % attenuated only the EFS-induced contractions. Sevo¯urane 1 % and 2 % had no effect. The release of [3H]-NE was inhibited b