Effects of mepivacaine, prilocaine and lidocaine on the induced constriction of the maxillofacial vasculature of the rat

Infusions of mepivacaine 5 or 50 micrograms.min-1 and prilocaine 50 micrograms.min-1 for 10 min into the maxillofacial arterial vasculature of the anaesthetized rat curtailed significantly rises in infusion pressure induced by the administration of adrenaline via the same route. The effect of mepivacaine was significantly greater than that of prilocaine. Such anti-constrictory action following intraluminal infusion, also shown by lidocaine in a previous study, contrasts with the variable (dilatory or constrictory) consequences of perivascular injections of the same local anaesthetics. Moreover, the equi-constrictory effects of (a) 1.10(-3) IU felypressin and (b) 120 ng adrenaline were attenuated to the same extent by lidocaine 5 micrograms.min-1 for 10 min, demonstrating that the anti-constrictory action of local anaesthetics is not specifically anti-adrenergic as has been suggested previously.     

EFFECTS OF I.A. LIGNOCAINE ON ADRENALINE-INDUCED VASOCONSTRICTION

The effects of i.a. administered lignocaine on the in vivo responseof the vascular bed supplied by the lingual, external maxillaryand posterior auricular branches of the common carotid arterywere studied in the rat. Infusions of lignocaine in concentrationsof 10–1000 µg ml^–1 administered at the rateof 0.05 ml min^–1 for 10 min did not affect vascular resistanceor arterial pressure in the common carotid artery. However,following such infusions, the increase of vascular resistancecaused by bolus doses of adrenaline (20–120 ng in 0.1ml) was inhibited, indicating lignocaine-adrenaline antagonism.Responses to adrenaline remained significantly depressed 60min after the termination of a 100-µg ml^–1 or higherlignocaine infusion. ^* Present address: Turner Dental School, University of Manchester,Bridgeford Street, Manchester M15.