DIURETIC-INDUCED HYPOKALAEMIA, PANCURONIUM NEUROMUSCULAR BLOCKADE AND ITS ANTAGONISM BY NEOSTIGMINE

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Abstract
The effect of hypokalemia on a neuromuscular blockade induced by pancuronium and its antagonism by neostigmine was studied in the cat anterior tibialis-peroneal nerve preparation using the constant infusion of pancuronium technique. Hypokalemia was induced by chronic administration of chlorothiazide. The infusion rate of pancuronium required to maintain a 90% depression of twitch tension was reduced from 0.72 .+-. 0.06 .mu.g per kg/min in the cats with a normal serum concentration of K (K+ = 4.4 .+-. 0.2 mmol/l; n = 7) to 0.41 .+-. 0.07 .mu.g per kg/min in the hypokalemic cats (K+ = 2.3 .+-. 0.1 mmol/l; n = 8). The dose of neostigmine necessary for 50% antagonism of the pancuronium-induced depression of twitch tension (ED50) was 10.0 .mu.g/kg in the cats with a normal K concentration and 18.5 .mu.g/kg in hypokalemic cats. Hypokalemia decreased the dose of pancuronium required for neuromuscular blockade and increased the dose of neostigmine required for antagonism of the block.