EFFECT OF LIGNOCAINE AND NITROUS OXIDE ON HYPOXIC PULMONARY VASOCONSTRICTION IN THE DOG CONSTANT-FLOW PERFUSED LEFT LOWER LOBE PREPARATION

The effects of lignocaine hydrochloride on hypoxic pulmonary vasoconstriction in the presence and absence of nitrous oxide were examined during constant-flow perfusion of the left lower lobe. Lignocaine had no effect on lobar pulmonary vascular resistance during lobar ventilation with oxygen or 7% oxygen in nitrogen. The substitution of nitrous oxide for nitrogen diminished the hypoxic vasoconstrictor response, whilst the subsequent infusion of lignocaine during 7% oxygen in nitrous oxide increased the response to a value which was not significantly different from that produced by 7% oxygen in nitrogen alone.