Increased sensitivity to depolarizing and nondepolarizing neuromuscular blocking agents in young rat hemidiaphragms

摘要: BACKGROUND Newborn neuromuscular junctions are more sensitive to d-tubocurarine than mature preparations. It is unclear whether the same modifications occur with newer nondepolarizing agents and depolarizing agent succinylcholine. The purpose of this study was determine relative sensitivity newborn succinylcholine five agents. METHODS phrenic nerve-hemidiaphragm preparation from 60 rats used, 30 aged 9-12 days (newborn) 27-33 (adult). Five each group were exposed one six blocking (d-tubocurarine, cisatracurium, atracurium, vecuronium, rocuronium, succinylcholine). Indirectly elicited twitch tension measured during control conditions in absence agent, followed by four concentrations Concentration-response curves constructed EC50 (concentration required produce 50% depression tension) obtained. Potency ratios (EC50adult/EC50newborn) derived for agent. RESULTS preparations significantly (P < 0.001) their adult counterparts all tested. For agents, potency ratio 6-12 range. EC50adult/EC50newborn as follows, decreasing order: d-tubocurarine, 1.68/0.23 microM; 2.73/0.47 5.47/0.59 9.7/0.78 12.3/1.9 microM. Succinylcholine three times potent rats, an 21.3/7.3 less drugs 0.02). CONCLUSION junction rat shows increased tested, including However, greater drugs. optimal dose these certain situations such cesarean section anesthesia neonates should be reassessed.