The effect of carbamate local anaesthetics on vascular smooth muscle.

The effect of carbamate local anaesthetics (pentacaine and heptacaine) on contractile responses induced by transmural nerve stimulation, exogenous noradrenaline (NA) and KCl, as well as on noradrenaline-induced Ca2+ mobilization, were investigated in isolated rabbit blood vessels under isometric conditions. Pentacaine and heptacaine inhibited the neurogenic contractions and those elicited by exogenous NA and KCl. The neurogenic contractions were more sensitive to the local anaesthetics than those evoked by exogenous NA. The onset of inhibition was slow and developed gradually. This inhibition was concentration-dependent and continued for several hours in spite of repeated washings of the vessels. Pretreatment of the vascular preparations with pentacaine and heptacaine reduced NA- and Ca2+-induced contractions in Ca2+-free K+-depolarizing solution. The Ca2+-contracted vessels were also relaxed by the anaesthetics studied. It is suggested that carbamate local anaesthetics inhibit not only neuronal conductance but also Ca2+ entry into the vascular smooth muscle cells and NA-induced release of intracellular Ca2+.